AIRWiki - User contributions [en]

LionHell McMillan

2015-04-22T16:39:04Z

AlessandroRosina:

{{Project
|title=LionHell McMillan
|coordinator=GiuseppinaGini
|students=VittorioLumare;
|resarea=Robotics
|restopic=Robot development;
|start=2011/09/10
|end=2012/07/20
|status=Closed
|level=Ms
|type=Thesis
}}

LionHell McMillan is an ''All Terrain Wheg Robot with Morphological Computation''

It has been developed in a Master Thesis work in Robotics and Artificial Intelligence and it has been modified and improved in a Master Thesis work in Robotics and Artificial Intelligence by Alessandro Rosina ( http://airwiki.ws.dei.polimi.it/index.php/LionHell_McMillan_II ) , changing the name from "LionHell McMillan" to "LionHell McMillan II".

Info about Thesis
TItle : '''All Terrain Wheg Robot with Morphological Computation'''
Robot Name: ''LionHell McMillan''
Correlator: Giuseppina Gini
Author: Vittorio Lumare
Area: Robotics and Artifical Intelligence
Start date: 2011/09/10
End date: 2012/07/24

{{#evp:youtube|QbMM9orBUn0|LionHell McMillan ROBOT - Walking on Rough Terrain|center|600}}

==The Idea==
===Starting Point===
The new locomotion system called [http://venomyeah.altervista.org/robotgarage/index.php/Wheg Wheg] (Wheel + Leg) enable mobile robots to move on rough terrains, using a simple control system .

===Objective===

The project objective is to test the wheg system , in order to find a design (both of robot, both of whegs) able to give the best agility on rough natural terrains.

==State of The Art==
* [http://biorobots.cwru.edu/projects/whegs/ Whegs I]
* [http://biorobots.cwru.edu/projects/whegs/ Whegs II]
* [http://biorobots.cwru.edu/projects/whegs/ Autonomous Whegs II]
* [http://biorobots.cwru.edu/projects/whegs/ Mini Whegs I]
* [http://biorobots.cwru.edu/projects/whegs/ PROLERO]
* [http://en.wikipedia.org/wiki/Rhex RHex]
* [http://worldwide.espacenet.com/publicationDetails/originalDocument?CC=EE&NR=05283B1&KC=B1&FT=D&date=20100415&DB=EPODOC&locale=en_EP Ratasjalg]
* [http://airlab.elet.polimi.it/index.php/EMBOT EMBOT]

==Simulations / Design==
===Simulation 1===
The first robot model has been taken from an existent robot : [http://airlab.elet.polimi.it/index.php/EMBOT EMBOT]

This is a video of the first simulation with this model

{{#evp:youtube|3aurAnj120Q|First simulation|center|400}}

As can be seen from simulation, robot model is unsuitable to the task.

The model has been then improved extending the body length of about 5 cm.

===Simulation 2===

Second simulation:

{{#evp:youtube|Ffu8eFY3Tug|Second simulation|center|400}}

Now robot is able to climb all the steps, but this is not enough.
The objective is harder: we want the robot to climb obstacles big as its body size, so I made another simulation with bigger obstacles:

{{#evp:youtube|_95LjvVVByw|Third simulation|center|400}}

Despite its longer body, the robot is unable to climb over the step.

This happens because it has no support in the back: when the back wheg (we see only
one back wheg because of the 2D simulation) rotates, the mechanical support of the
servomotor is the robot chassis, which starts rotating clockwise, making the robot
falling backwards.

The solution to this problem is to avoid the chassis rotation.

How to avoid the chassis rotation?

A simple approach is to add a '''fixed link''' in the back ,
such a kind of '''tail''', so that when the chassis starts rotating clockwise , the tail will touch the ground surface '''blocking the rotation'''.

===Simulation 3===

New Model:

* New central wheg
* New link added to body
* Joint in the body center
* Tail added to the back
* Wheg foot design improved to give better grip

{{#evp:youtube|IVa5XNEc3KA|Fourth simulation|center|400}}

As we can see , the robot is able to walk on very rough surface terrain.

He goes on even in presence of high surface spikes, thing that would have been not
possible for the previous robot model.

This better behavior is principally due to the
new central wheg added to the model, and to the slight body flexibility, due to the
action of a spring and a damper in the body center.

Thanks to the '''tail action''', robot '''never falls on his back'''.

==The Real Robot==

===First Prototype===

[[file:lionhell_v1.jpg|600px|LionHell First Prototype]]

===Final Prototype===

[[file:lionhell_v2.jpg|600px|LionHell Final Prototype]]

=Hardware=

In this section all the hardware components will be illustrated, excluding structure
because it was yet discussed in the previous chapters.

==Servomotors==
[[file:dynamixel-ax-12a.jpg|right]]

In this robot the '''servomotors''' are the only actuators.

These servos have been taken from a '''Robotics kit''' called '''Bioloid''', commercialized by
'''Robotis'''.

The servomotor model is '''Dynamixel AX-12'''.

Dynamixel servos are very versatile, quite strong and can be used in '''two modes''':

* ''Continuous Rotation mode''
* ''Position mode''

The only limit of these servos causing some problem in this work is a '''60° dead-band '''.
When motor shaft falls in this range, '''position''' is '''not retrievable''' from the '''internal potentiometer''' .
This was a '''problem''' in continuous rotation mode, because I could not control the servo '''position''' in that range.
This '''limit''' avoided me to '''synchronize''' all the six whegs to obtain a perfect control in climbing over obstacles.
In fact I ended up with a simple open-loop motor control.

The other 3 servos were used in Position Mode:
*Two servos for the '''body joint''' in the center of robot
*One servo for the '''tail'''

Illustration 42: Servomotor - Dynamixel AX-12

Table 1: Servomotor - Dynamixel AX-12

In this case the dead band did not cause any problem, because a 180° movement was sufficient for the purpose.

I had to use '''two servos''' for the '''body joint''', because of the '''high torque''' needed to move the head and the frontal pair of whegs.
At a first time I tried to use one servo, but it was subject to overheating, until it burned.
Using two servos in '''parallel''', ''mechanically coupled'', permitted a perfect control of the joint, without overheating.

==Control Board==
[[file:cm510.png|right]]
The '''central processing unit''' used is a ''CM-510''.

It’s a development board producted by Robotis, and its fully compatible with
''Dynamixel AX-12'' '''servos'''.

'''CM-510'''

Weight 51.3g
Controller ATMega2561
Working Voltage
Allowed Range : 6.5V ~ 15V
Recommended Voltage : 11.1V (Li-PO 3cell)
Consumed Current
When IDLE : 50mA
External I/O Maximum Current : 0.9A
Total Maximum Current : 10A (Fuse)

Table 2: Control Board – CM-510

Illustration 43: Control Board - CM-510

This board is featured with standard '''Dynamixel ports''', plus 6 other '''general purpose
ports'''.

Each general purpose port is featured with 4 usable '''pins''':
* Ground
* Power (5V)
* Digital I/O
* Analogue Input (0V– 5V)

I used these ports to connect all '''peripheral sensors'''.

Since I had too many sensors for the available ports, I had to built '''two multiplexer
boards''':
* One board to multiplex 4 rangefinders
* One board to multiple 3-axis accelerometer

The boards inputs have not been fully used, so there are '''available channels''' for an
eventual '''future use'''.

==Sensors ==

The most critical aspects of perception in this robot are:
* Terrain sensing.
* Robot inclination with respect to gravity force vector.

===Multiplexer Boards===

I designed and builded two multiplexer boards: one for the IR-rangefinders , one for the 3-axsis-accelerometer.

The board below multiplexes the analog signal from each of the four used IR Sharp Rangefinders, in order to use a single analog input on the CM-510 Board.
[[file: Rangefinders_Multiplexer_Board.jpg]]

The board below multiplexes the analog signal from each accelerometer channel, in order to use a single analog input on the CM-510 Board.

[[file: Accelerometer_Multiplexer_Board.jpg]]

For time reasons I've implemented both boards quickly by manually building the circuit tracks.

In more relaxed circumstances I would have made the same boards by PCB photo-etching.

===Infrared Rangefinders===
[[file:GP2D120X.jpg|right]]
Terrain need to be analyzed in order to know if it's possible walking over it.

If the terrain roughness is high, it is avoided: the robot turns left or right searching for a
better path.

The key concept adopted to detect if a terrain is too rough is this: robot needs a planar
surface in order to climb over it without possibility of falling.

In order to understand if terrain is planar, some IR rangefinders have been used.
This sensors are produced by SHARP, and the model is GP2D120X.

Main specifications
'''GP2D120X'''
Measuring distance range 3 - 40 cm
Output terminal voltage 0.25 – 0.55
Average supply current 33 - 50 mA
Operating supply voltage 4.5 – 5.5 V

The output distance characteristics of sensor is shown in the picture below.

[[file:SHARP_GP2D120X_diagram.png]]

As we can see , the characteristic is not linear.

In order to take correct distances (in cm ) from the sampled values, I wrote a lookup table with 17 values and the corresponding tension value (represented as number )

unsigned short sharp_calib[17][2] =
{
{63,40},
{71,35},
{85,30},
{106,25},
{132,20},
{153,18},
{165,16},
{192,14},
{214,12},
{257,10},
{286,9},
{319,8},
{360,7},
{415,6},
{480,5},
{562,4},
{613,3}
}

The C function (used in the firmware code):

''float readSharp_cm(unsigned char addr)'' interpolates the values in the lookup table, converting the tension value to distance in centimeters.

Four rangefinders are disposed onto a ''SensorBar'' horizontally fixed on the head of the robot, as we can see in the picture below.

[[file:Sensor_Bar.png]]

Three of these sensors point straight towards the terrain in front of robot, analyzing
terrain’s surface by sensing the distance from bar in three different points.

One sensor points in the march direction and is used to detect obstacles.

The sensors are disposed in this way:
* two in the center of the bar (one pointing down, one pointing forward)
* on in the left limit of the bar (pointing down)
* one in the right limit of the bar (pointing down)

Robot takes samples from all three sensors, and then compares them: If the distances are
all the same (with a little tolerance), terrain is walkable. If the difference between right
and center distances is high, robot turns slightly right If the difference between left and
center distances is high, robot turns slightly left.

Before using this approach, I tried to take distances with a single sensor turret, actuated
by another Dynamixel servo, but this solution has revealed to be too slow and power
consuming, and was abandoned.

As said before in the Introduction of this thesis, this sensor-bar has been conceived
thinking at the embodiment concept: it moves with the robot body, giving
automatically the sensors the best point of view (in order to have a good perception of
terrain and obstacles) automatically. Sensor-bar position and orientation change
according to the body configuration, which in turn changes according to the interaction
with the environment.

===3-axis Accelerometer===
[[file:acc-3axis.jpg|right]]
In order to know the robot inclination with respect to gravity force vector, a 3-axis
accelerometer has been used.

This sensor is produced by Freescale Semiconductor and the model is MMA7361 .

'''MMA7361'''

Low Voltage Operation 2.2 V – 3.6 V

High Sensitivity 800 mV/g @ 1.5g

Selectable Sensitivity (±1.5g, ±6g)

Low Current Comsumption 400 µA

Table 4: Accelerometer - MMA7361

I bought a ready to use “breakout-board” with sensor yet mounted on: you can see it in
the photo above.

In this application the selected sensitivity is ±1.5g

The sensor has been mounted on the chassis, the most possible near to the '''center of mass''' of robot.

The ''robot center'' changes as the '''body joint''' moves, so a perfect positioning of the accelerometer has not been possible, but this was not a problem.

The accelerometer orientation is:
* x axis points towards robot forward sense of march, horizontally with respect to floor
* y axis is disposed horizontally with respect to floor, pointing to the left of robot
* z axis exactly in vertical position, pointing against gravity force vector.

The convention I used is to consider each axis in standard orientation when it is '''parallel''' to the '''plane normal to gravity vector'''.

For each axis, the implemented controller computes the ''displacement_angle'' from ''standard orientation''.

The method used to determine this displacement_angle is very simple: Each of three channels values are normalized with respect to the gravity force When robot is in standard position, values are 0 for y,x channels, 1 (100% gravity force) for the z channel.

The '''orientation of each axis''' is computed as:

''displacement_angle = arcsin(channel_value_N) ''

where ''channel_value_N'' is channel value '''normalized to gravity module'''.

Each channel value is equal to cosin(gamma), where gamma is the angle between the axis and the gravity vector

'''Computation of displacement_angle:'''

''channel_value = g * cosin(gamma) ''

but we want to know the normalized value , so channel_value_N = channel_value /

''g = cosin(gamma) ''

The standard position is 90° wrt gravity vector, so the displacement_angle, we call it delta, is:

''delta = 90° - gamma ''

so

''gamma = 90° - delta ''

so

''channel_value_N = cosin(90° - delta) ''

Knowing that

''sin(delta) = cosin(90° - delta) ''

we can say

''channel_value_N = sin(delta) ''

and finally

''displacement_angle = delta = arcsin(channel_value_N)''

==Power==
===Transformer===

Robot has been powered by AC-DC transformer during the development phase.
The transformer I used has this specifications: Output Voltage 12V
* Max current 5A max

[[file:Robotis_Transformer.jpg]]

===Batteries===

When the robot development has been completed, robot has been equipped with a couple of 2-cells lithium polymer batteries.

Batteries specifications:
* Output Voltage 7.5V
* Battery capacity 2500 mAh

Due to the lower tension of battery with respect to transformer, servo’s speed has been slightly increased in order to ensure a sufficient torque

[[file:LionHell_Battery.jpg]]

=Firmware=

The implemented firmware was initially conceived to be the only program to control the
robot.

After some testing, the used microcontroller has revealed to be too less powerful in
order to obtain an acceptable loop speed and a sufficiently complex computational
capability. A complex control like motion planning needs a more performant
computational system.

I decided to mantain a fast reactive behavior based control in the main loop, adding a
serial communication phase in order to allow data exchange with external control
hardware, like a PC. A deep analysis of the behavior based control in mobile robotics
can be found in a recent work from L. De Silva and H. Ekanayake [18]: they discuss
several behavior control paradigms, including the subsumption.

In remote control applications, a simple control like this will act as a cerebellum,
assisting the remote user in the motion control. A recent work on this topic has been
made by Shigang cui, Zhengguang lian, Li zhao, Zhigang bing, Hongda chen [19].

They discuss several behavior control paradigms, including the subsumption.

The implemented loop resulted to be very fast, and sufficient to manage the most
critical behaviors, like falling prevention and obstacle climbing.

The main control loop consists of this macro blocks:
*Read and Communicate Sensors Data
*Set Speed According to Body Inclination
*Main Behaviors
**Jump Down Behavior
**Terrain Check Behavior
**Approaching Obstacle Behavior
**Adapt to Floor Behavior
*Walking Actions
**Go Backward
**Turn Left
**Turn Right
**Restart Walking
**Stop Walking
*Tail Control Section
**Tail Behaviors Manager
**Tail Behavior 1: Avoiding Falling Backward
**Tail Behavior 2: Climbing

==Read and Communicate Sensors Data==
The first thing to do in the main loop is reading sensors, and communicating them to the
eventual external hardware through the serial-usb link.

===Reading Sensors===
This is done using this funcion:

*void readAllSensors(Sensors *s);
It reads all sensors data saving them into a Sensors structure.

The above function calls a specific read function for each sensor:
*float readSharp_cm(unsigned char addr);

It reads the value of Sharp sensor mapped at address addr and convert it to distance
in centimeters.

Each address indicates a channel on the distance sensors multiplexer.
*float readAccDeg(unsigned char addr);

It reads the angle value from the Accelerometer Channel at address addr, and
converts it to degrees.

Each address indicates a channel on the accelerometer multiplexer, and each
multiplexer channel correspond to a single channel on the accelerometer.

Accelerometer, as seen before, has 3 channels, one for each axis.

===Communicating sensor data===
The communication is performed through a serial link in asynchronous mode, at a
baudarate of 57600 bps.

The serial format is 8bit, no parity, 1 stop bit.

The data format is the following:

FC <FC>\tGC <GC>\tGL <GL>\tGR <GR>\tZ <Z>\tX <X>\tY <Y>\tAD <AD>\tTD <TD>\n

and this is the meaning of the tags:

<FC> : Distance in cm from Central Front Sensor
<GC> : Distance [cm] from Central Ground Sensor
<GL> : Distance [cm] from Left Ground Sensor
<GR> : Distance [cm] from Rigth Ground Sensor
<Z> : Normalized [adim] value from Z axis Channel on Accelerometer
<X> : Normalized [adim] value from X axis Channel on Accelerometer
<Y> : Normalized [adim] value from Y axis Channel on Accelerometer
<AD> : Abdomen Inclination angle [deg] with respect to the robot body
<TD> : Tail Inclination angle [deg] with respect to the robot body

This data is intended to be read from the serial-usb interface using a sscanf function
implemented in any programming language.

All transmitted values are integers ( %d in C, C++ format ).

This is the output we get connecting to it :
...
FC 39 GC 17 GL 19 GR 19 Z 932 X -24 Y 43 AD -34 TD -37
FC 39 GC 16 GL 18 GR 18 Z 1000 X 48 Y 92 AD -34 TD -37
FC 39 GC 15 GL 18 GR 19 Z 1000 X 54 Y 37 AD -34 TD -37
...

==Set Speed According to Body Inclination==

In order to adapt the servomotors torque to the current ground surface, the robot must
increase their speed according to the vertical inclination of the robot body.

If the inclination value is high and positive, the robot is walking uphill, so the torque
must be increased.

The following instruction sets the nominal speed for all whegs servos: ''dnspeed''

(Desidered Nominal Speed) : dnspeed = (600 + 4 *sensors.body_inclination_xg);

Dynamixel servos accept a speed value from 0 to 1023.

Here we set 600 as base-speed, then adding a variation proportional to inclination.

If the inclination is negative (robot walking downhill) the added variation will be
negative, ending up with a speed value smaller than base-speed.

==Main Behaviors==
This behaviors determine the commands that will be sent to the whegs in the following Walking Actions section.

All this behaviors are exclusive, and they have descending priority, so that the first has
the high one and the last has the lower one.

Each behavior has a trigger event that I call “situation”.

Before going to process the behaviors, some data must be prepared.

''float ld = abs((int)(sensors.distance_floor_left – sensors.distance_floor_center));''

''float rd = abs((int)(sensors.distance_floor_right – sensors.distance_floor_center));''

The above two instructions compute two difference values:
*ld : '''Left Difference''' This is the difference value between the left terrain distance sensor and the center terrain distance sensor
*rd : '''Right Difference''' This is the difference value between the right terrain distance sensor and the center terrain distance sensor.

This difference values will be used within the following behaviors in order to detect the current situation.

===Jump Down Behavior===

'''Situation 1:'''
''Robot’s head is facing floor with an abdomen inclination inferior to -45 ° with respect to gravity force vector''
''AND distance from floor along the view axis is less than 30 cm.''

In this situation the robot will probably crash his head to the floor if it doesn’t lift it Instantly, so the first command is to stop walking.

This situation requires that the distance from floor is less than 30 cm, so that the robot could “jump” toward floor without destroying itself.

'''Behavior 1:'''
''Then the robot lift up the abdomen until it exits from this situation.''

'''Code'''

if (sensors.abdomen_inclination_g < -45 && sensors.distance_front_center < 30){
stop();//STOP ROBOT
while(sensors.abdomen_inclination_g < -45 && sensors.distance_front_center < 30)
{
//LIFT ABDOMEN
dpAbd = dpAbd + 1;
setAbdomenDeg(dpAbd, 1000);//Lift
sensors.abdomen_inclination_g = getAbdomenDegG();
sensors.distance_front_center = readSharp_cm(4);
}
}

===Terrain Check Behavior===

This behaviors uses the Left Difference (ld) and Right Difference (rd) described before in chapter 5.3.

'''Situation 2:'''
''Left Difference or Right Difference is greater than 8 cm.''

This means that terrain is not uniform.

'''Behavior 2:'''
''turn where the difference is smaller. ''

'''Code:'''

if(ld > 8 || rd > 8)
{
if (ld >= rd) {turnR = 1; turnL=0;}
if (ld < rd) {turnL = 1; turnR=0;}
}

===Approaching Obstacle Behavior===

'''Situation 3 :'''
''There is an obstacle near in front of the robot in central position.''

Obstacle is considered near if distance is less than 15 cm.

'''Behavior 3 :'''
''climb over the osbtacle.''

The sequence of actions to perform is :

1. stop walking
2. lift head (abdomen) until obstacle diappears and abdomen inclination doesn't
exceed 80°. This limit has been imposed in order to avoid vain climbing efforts
on almost perpendicular walls.

Code:
if (sensors.distance_front_center < 15)
{
stop();
while(sensors.distance_front_center < 15 && sensors.abdomen_inclination < 80)
{
if (dpAbd > 80)dpAbd = 80; //Upper Bound setAbdomenDeg(dpAbd, 200);//Lift up
abdomen sensors.distance_front_center = readSharp_cm(4); //read distance
}
}

===Adapt to Floor Behavior===

'''Situation 4 :'''
''Distance from floor is greater than 23 cm ''

This happens when the abdomen is too high, or when robot approaches a descent .

In order to have a good sensing of the terrain the sensors array should point the floor perpendiculary (and so abdomen should be parallel to terrain).

Due to the geometry of robot (his height is about 23 cm), lowering abdomen until it's 23 cm distant from floor will put it parallel to floor surface.

'''Behavior 4 :'''
''Lower the abdomen until distance of head from floor is less than 23 cm ''
''or it's tilted down more than 75° ''

'''Code:'''
if(sensors.distance_floor_center > 23 )
{ // Floor too distant ..
stop(); //stop walking
while(sensors.distance_floor_center > 23 && sensors.abdomen_inclination > -75)
{
dpAbd = dpAbd – 1; // Lower down Abdomen
if (dpAbd < -75)dpAbd = -75; // Limit value
setAbdomenDeg(dpAbd, 200);//send command to servomotor
sensors.distance_floor_center = readSharp_cm(6);
}
}

==Walking Actions==
The purpose of this section is to send commands to servomotors, in order to perform the movements requested by the previous behaviors section.

The first instruction of this section is a control statement that checks if the robot should be walking or not.

This is accomplished by reading the value of a condition variable called ''walking''.

This condition variable is set within the previous behaviors section.

'''Code:'''
if (walking==1)
{
…
}

The other condition variables used to control this section are:

''turnL//Turn Left ''
''turnR//Turn Right ''

===Go Backward===

The way behaviors inform this section that the robot must bo backward is just enabling both turn condition variables : turnL and turnR.

'''Code:'''
If(turnL && turnR)
{
int i ;
for (i=0;i<3;i++){//Go Back
dxl_write_word( whegs_sx[i], P_MOVING_SPEED_L, 1424 );
dxl_write_word( whegs_dx[i], P_MOVING_SPEED_L, 400 );
_delay_ms(20000);//Mantain behavior
//Disable behavior..
turnL = 0;
turnR = 0;
}
}

===Turn Left===
Turning Left is accomplished by going backward with the left train of whegs, keeping still the right one.

Behavior is mantained for a while, and then condition variable are cleared.

if(turnL)
{
int i ;
for (i=0;i<3;i++) //iterate on all servos {
dxl_write_word( whegs_sx[i], P_MOVING_SPEED_L, 1424 );
dxl_write_word( whegs_dx[i], P_MOVING_SPEED_L, 0 );
_delay_ms(20000);//Mantain behavior
//Disable behavior..
turnL = 0;
turnR = 0;
}
}

===Turn Right===

Same as Turn Left.

if(turnR){
int i ;
for (i=0;i<3;i++){
dxl_write_word( whegs_sx[i], P_MOVING_SPEED_L, 0 );
dxl_write_word( whegs_dx[i], P_MOVING_SPEED_L, 400 );
_delay_ms(20000);//Mantain behavior
//Disable behavior..
turnL = 0;
turnR = 0;
}
}

===Restart Walking===
This section is needed to make the robot restart walking in two cases:
*it was stopped before
*it was turning

if (!(turnL + turnR)){//If not turning
go_fwd();//Go forward
}

===Stop Walking===

If the walking condition variable is not set, the robot just stops walking.

If (walking==1)
{
…
}
else
{
stop(); //Stop Walking
}

==Tail Control Section==
In this section we control the tail, in order to help robot to accomplish some tasks.

This part is located after the Walking Actions section, because it do not modifies any walking control variable.

===Tail Behaviors Manager===
This section acts like a behavior manager, it mantains a behavior until it accomplishes its task.

It checks if tails has reached (with little toelrance) the desidered position and, in positive case, it disables the torque on tail servomotor.

Then it disables all tail behaviors by clearing dpTail control variable.

// Check if desidered Tail position (if it was set) has been reached
if(dpTail != -1 && abs((int)dpTail - (int)pTail) < 50)
{
dxl_write_word( 1, P_TORQUE_ENABLE, 0 );
// Disable Torsion Servo
// Needed to shut off tail behaviors
// activated in previous loop cycle
dpTail = -1; //disable desidered Tail position
}

===Tail Behavior 1: Avoiding Falling Backward===

'''Situation 5 : '''
''• Tail is high (wrt body)''
''• Abdomen isn't low (wrt body) ''
''• Body is tilted up more than 45° with respect to gravity vector ''

In this situation the robot is likely to fall backward, so robot body must be put in a less dangerous configuration.

'''Behavior 5 : '''
''Lower the tail until it’s almost in line with body (horizontal position) ''

Putting tail in line with body makes the back of the robot to lift up.

In this way robot’s center of mass is moved forward, towards the central position, putting the whole body in a safer position.

'''Code:'''
if ( parallel && pTail < 300 && // Tail is high
getAbdomenDeg() >-10 && // Abdomen isn’t low (wrt body)
readAccDeg(1) > 45) // Body is tilted up more than 45 deg wrt g
{
//avoid falling backwards
dpTail = 500;
dxl_write_word( 1, P_GOAL_POSITION_L, dpTail );
dxl_write_word( 1, P_MOVING_SPEED_L, 210 );
}

===Tail Behavior 2: Climbing ===
'''Situation 6 : '''
''• Tail is slightly up (wrt body) ''
''• Abdomen is slightly low (wrt body) ''
''• Body is tilted up more than 60° with respect to gravity vector ''

In this situation, robot's body is very tilted up, and abdomen is slightly tilted down.

This means that robot is climbing over an obstacle.

'''Behavior 6 :'''
''Lower the Tail until it’s quite lower than the horizontal position.''

If the tail is slightly upper than the horizontal position, it should be lowered down, in order to help robot in the climbing task.

Lowering tail helps because in this way the robot’s back is lifted up, and this moves the center of mass forward, causing the frontal whegs to exert a greater pressure on terrain.

Great pressure on terrain ensures more grip, and so robot can easily bring its body forward, accomplishing the climbing task.

if ( parallel && pTail < 450 && // Tail is slightly up
getAbdomenDeg() < -20 && // Abdomen is slightly low
readAccDeg(1) > 60 ) // Body is tilted up more than 60 deg wrt g
{ //climb
dpTail = 712;
dxl_write_word( 1, P_GOAL_POSITION_L, dpTail );
dxl_write_word( 1, P_MOVING_SPEED_L, 210 );
}

==Flow Chart==

[[file:lionhell_firmware_flow_chart.png|Firmware Flow Chart]]

=Experiments=

==LionHell McMillan walking on rough natural terrain ==
{{#evp:youtube|QbMM9orBUn0|LionHell McMillan ROBOT - Walking on Rough Terrain|center|600}}

=Download=
*[[http://www.robotgarage.org/wiki_files/Firmware.zip Firmware Source Code and Object File ]]
*[[http://www.robotgarage.org/wiki_files/Player_Server_Plugins.zip Player Server Plugins Source Code]]
*[[http://www.robotgarage.org/wiki_files/Wheel_Drawing.rar Wheg Drawing]]

LionHell McMillan II

2015-04-22T16:35:31Z

AlessandroRosina:

{{Project template
|title=LIONHELL MCMILLAN II: RIPROGETTAZIONE DI UN ROBOT ESAPODE BIOLOGICAMENTE ISPIRATO PER AREE MORFOLOGICAMENTE INSTABILI
|image=[[File:LionHell-image.jpg|200px|thumb|left|LionHell McMillan II]]
|description=Hexapode wheg robot
|tutor=Giuseppina Gini
|start=01/09/2014
|number=1
|cfu=20
}}

<p><br />
LionHell McMillan II is an hexapode wheg robot. LionHell McMillan has been developed in a Master Thesis work in Robotics and Artificial Intelligence by Vittorio Lumare ( http://airlab.ws.dei.polimi.it/index.php/LionHell_McMillan )
and it has been modified and improved in a Master Thesis work in Robotics and Artificial Intelligence by Alessandro Rosina ( http://airlab.ws.dei.polimi.it/index.php/User:AlessandroRosina ) , changing the name from "LionHell McMillan" to "LionHell McMillan II".
</p><p>Info about Thesis
</p>
<pre>TItle : LIONHELL MCMILLAN II: RIPROGETTAZIONE DI UN ROBOT ESAPODE BIOLOGICAMENTE ISPIRATO PER AREE MORFOLOGICAMENTE INSTABILI
Robot Name: LionHell McMillan II
Supervisor: Giuseppina Gini
Correlator: Vittorio Lumare
Author: Alessandro Rosina
Area: Robotics and Artifical Intelligence
Start date: 2014/09/10
End date: 2015/04/29
</pre>

[[File:LionHell-image.jpg|400px]][[File:LionHell II 2.jpg|400px]]
<br />
[[File:LionHell II 3.jpg|300px]][[File:LionHell II 4.jpg|400px]]

<h2> <span class="mw-headline" id="state_art">State of the Art</span></h2>
<h3> <span class="mw-headline" id="Wheg">Wheg</span></h3>

The locomotion system is the key element that allows the robot to
interface and explore the surrounding environment and requires a careful choice
that meets the requirements of handling, mechanical simplicity and fluidity
motion, ensuring, in this case, the possibility to move easily
on rough terrain, overcoming obstacles of small and medium
size.

<h4> <span class="mw-headline" id="Definition_Wheg">Definition of the Wheg</span></h4>

[[File:Description wheg.PNG|300px]][[File:Wheg 0 rotazione.PNG|600px]]

The Wheg are a mechanism of locomotion for robots that combine
simplicity of movement of a wheel with the ability to scale and to overcome
obstacles arising from the use of the legs. The acronym derives
by the combination of words wheel and leg and mechanically it
consists of a central rotary axis and which are connected one or more bars
which perform the function of the legs.
The operation of a Wheg is extremely simple: the three legs are connected to a central axis that rotates
on itself and the point of contact with the ground is made from the end
of the leg.

<h4> <span class="mw-headline" id="_vs_Wheel">Wheg vs Wheel</span></h4>

The superiority of Wheg comparison to the use of a simple wheel is easily
demonstrated:

[[File:Ruota1ostacoloPiccolo.png|300px]][[File:Ruota2ostacoloPiccolo.png|300px]][[File:Ruota3ostacoloPiccolo.png|300px]]

<ol>
<li> Consider a wheel that is about to face an obstacle placed on the floor, much smaller than the radius
the wheel itself; </li>
<li> Once the wheel comes into contact with the obstacle, the clutch
that is generated will force the point of contact to remain in the same
position and while the torsion of the wheel will continue to act, the point
contact will function as a pivot. If the power of the engine will be
enough the result will be that the wheel will walk across continuing
in its path; </li>
</ol>
[[File:Ruota1ostacoloGrande.png|500px]]
<ol>
<li>Now consider a similar situation, in which, however, the obstacle that
wheel must be facing the same overall height of its radius (h similar to r). In this case the contact point is on the side of the obstacle,
and not above as in the previous case and the clutch that you should
come and create so that it can be climbed should be such that
allow the robot to move in a vertical manner with respect to the obstacle.
Typically, this situation is not a realistic scenario and the
experiment result will be that the wheel will start to slip on the spot,
continuously changing the point of contact with the obstacle. Due to the fact
the wheel would fail in this scenario, the wheel would fail for all
scenarios where h > r as the contact point will always be on the
side of the obstacle and not above. </li>
</ol>

[[File:Wheg1ostacoloGrande.png|300px]][[File:Wheg2ostacoloGrande.png|300px]][[File:Wheg3ostacoloGrande.png|300px]]

Consider now the previous example, in which h is similar to r, but where in place
of the wheel there is a Wheg three legs (in figures can be
observe the presence of a circle around the Wheg: this circle is purely
illustrative and serves only to relate the size of Wheg
compared to those of the wheel):
<ol>
<li>First, you can see the huge gap that the structure
presents, space that will be used to your advantage: the structure
is in fact able to exploit the empty space, facing the obstacle
from above and not from the side as in the case of the wheel; </li>
<li>The force exerted by the engines and the twist of Wheg will do the rest,
allowing the exploitation of the point of contact as a pivot to raise the Wheg frame and overcome the obstacle (you
always remember that the circle only serves to show the trajectory
of the three legs); </li>
</ol>

[[File:Wheg1ostacoloEnorme.png|400px]]

<ol>
<li>Now consider another example, in
where we have h > r, and in particular the case in which h = 3/2 r (as
there are 3 legs). In this extreme case the Wheg will not be
able to overcome the obstacle: the ability to climb it depends on how the
Wheg is capable of penetrating the profile of the obstacle. You can get
this goal by reducing the angle between the two upper legs, but this
undermine the structure of Wheg making unstable. </li>
</ol>

From this analysis it is possible to highlight the main advantages and disadvantages
of using a Wheg:
<ul>
<li> Pro: the ability to climb obstacles of greater height than those
addressed by a wheel having the same radius; </li>
<li> Pro: the speed of movement of the robot is still high; </li>
<li> Pro: the greater simplicity of construction and control compared to
a leg, which must necessarily be controlled by two or
three actuators; </li>
<li> Cons: The land on which it moves must be rough, in order to
do strength and be able to overcome the obstacle; </li>
<li> Cons: Legs too thin could sink surfaces
soft or non-rigid, such as sand or mud, due to the
reduced contact surface; </li>
<li> Cons: If your legs hit moving parts, such as long grass or cables
very thin, the Wheg could be twisted, latching
and risking damage to the robot in the case where the motors
trying to do too much force to break free. </li>
</ul>

<h3> <span class="mw-headline" id="Wheg_robot">Robot with whegs</span></h3>

The Wheg is a system of locomotion used in many robot exploration, from Prolero, the first robot ever to be equipped
with Wheg, is a robot equipped initially with 4
Wheg and later of 1 to 6 Wheg leg, was developed by Martin
A. Alvarez, P. de Peuter, Hillebrand JR., P. Putz, Matthyssen A. and de Weerd
J. in 1996. Subsequently,
many other robots have followed his example:
<ul>
<li> Climbing Mini Whegs is a
robot with 4 Wheg each with 4 legs able to adhere to various surfaces,
was developed at Case Western Reserve University; </li>
<li> Embot is a robot equipped with 4 Wheg each with 3
legs, was developed at the Politecnico di Milano from Gaibotti
A. and F. Mariggiò in 2011; </li>
<li> Lunar Whegs is a robot equipped with
6 Wheg each with 3 legs, was developed by Dunker PA in 2009; </li>
<li> Mini-Whegs IV is a small robot
dimensions with 4 Wheg 3 legs, was developed by Morrey
J., B. Lambrecht, Horchler A., Ritzmann R. and R. Quinn in 2003; </li>
<li> OUTRUNNER is a robot equipped with 2 racing
Wheg each with 3 legs, was developed by S. Cotton, C. Black, Payton
N., K. Ford, and Howell W. Conrad, J. in 2014;</li>
<li> Ratasjalg is a robot equipped with only 2
Wheg each with 6 legs, which in case of need can become wheels,
was developed and patented by R. Sell at Tallinn University of
Technology in Estonia in 2007;</li>
<li> RHEX is a robot with 6 to Wheg
1 leg, was developed by Altendorfer R., N. Moore, Komsuoglu
H., M. Buehler, H. Brown Jr., McMordie D., Saranli U., R. and Full
Koditschek D in 2001;</li>
<li> Termes is a robot with 4 to Wheg
3 legs, was developed by Werfel J., K. Petersen, and R. Nagpal in
In 2014;</li>
<li> USAR Whegs is a robot equipped
4 Wheg 4 legs, was developed by AJ Hunt at Case
Western Reserve University in 2010.</li>
</ul>

<h2> <span class="mw-headline" id="CM_LionHell_II">Control and Mobility in LionHell II</span></h2>
<h3> <span class="mw-headline" id="Wheg_Lionhell_II">Wheg in LionHell II</span></h3>

[[File:Wheg LionHell.png|290px|right|Wheg of LionHell]]
[[File:Wheg LionHell II.png|300px|right|Wheg of LionHell II]]

The whegs are a mechanism of locomotion for robots that combine
simplicity of movement of a wheel with the ability to scale and to overcome obstacles arising from the use of the legs. The acronym derives
by the combination of words wheel and leg, and mechanically consist of a central rotary axis which are connected one or more bars
which perform the function of the legs. <br />
LionHell II has a total of 6 Wheg and each Wheg is composed of 3 bars arranged at 120° apart from each from the other, the ends of which is
mounted a foot slightly curved so as to ensure a secure grip on the ground. The movement of Wheg is simultaneous and each Wheg is controlled
by an independent motor that works in continuous mode, ensuring a smooth motion and robot suitable for every situation.
The Wheg that owns LionHell II is characterized by:
<ul>
<li> a structure baseline, aluminium, guarantees the point of contact with the central hub; </li>
<li> a basal structure of the foot, wood, molded according to an embodiment curve so as to adapt better to the ground and avoid jolts; </li>
<li> the foam, in contact with the foot structure, reduces shocks of the robot in contact with the ground; </li>
<li> rubber, in direct contact with the ground, protects the foam wear and allows the robot to move easily on any surface area; </li>
<li> the symbol allows to easily identify the components of the Wheg and position of the leg in the same robot; </li>
<li> the outline contour allows to understand intuitively the position with which the other members of Wheg be mounted. </li>
Compared to the previous model, we have kept the metal rod base and the rubber that was removed from the foot, since the movement of the same
LionHell would irreparably damaged the Wheg and in particular the delicate foothold.

<h3> <span class="mw-headline" id="Central_Passive_Joint">Central Passive Joint</span></h3>
This part will describe the role of the new central passive joint and the increase of the degrees of freedom that resulted.

<h4> <span class="mw-headline" id="DOF_LionHell_II">Degrees of Freedom of LionHell II</span></h4>
The number of degrees of freedom (DoF) of a material point is the number of independent variables needed to determine
uniquely its position in space (coordinates).
The degrees of freedom is a term used to define freedom of movement of a robot in the three spatial skills, and the
number of degrees of freedom of defining a robot configuration.
LionHell II is a hexapod robot equipped with Wheg, tail, a coupling motor that allows him to lift the front in order to better deal with
obstacles, and finally a central passive joint. In the figures you can
observe the degrees of freedom of LionHell II:
<ul>
<li> the movement of Wheg: each wheg has 1 degree of freedom, for a total of 6 degrees of freedom; </li>
<li> the movement of the joint motor and tail, each of which adds 1 degree of freedom, for a total of 2 degrees of freedom; </li>
<li> the central passive joint which was added later, and the green lines trace a possible movement of the front part of the robot. </li>
</ul>
The creation of a robot with a central joint in more passive arose from the idea to facilitate the movements when cornering and allow a more fluid
movement. In the next subsection we will explain in more detail the joint that has been added.

[[File:Dof wheg LionHell.PNG|300px|DoF of the whegs of LionHell II]][[File:Dof giunto LionHell.PNG|300px|DoF of the central passive joint of LionHell II]][[File:Dof testa coda LionHell.PNG|300px|DoF of the frontal part and of the tail of LionHell II]]

<h4> <span class="mw-headline" id="CPJ_LionHell_II">Central Passive Joint of LionHell II</span></h4>
LionHell II is equipped with a passive joint central, whose role is to accompany the movement of Wheg facilitating the movement when the
robot is going to bend. The passive coupling is constituted by:
<ul>
<li> a connecting member which allows rotation of a part of the body of LionHell II; </li>
<li> a pair of metal bars at the two ends of the connecting element, which are part of the security system; </li>
<li> two screws at the ends of the bars, their role is to define the angle of maximum rotation of the joint. </li>
</ul>
The screws may be replaced with shorter or longer, at difference if you want a rotation angle lower or higher. In
current state, the joint is able to rotate 10° to the right or to the left, while with the total absence of the screws the angle increases up to 30°. The addition
screw was necessary as it was presented the risk that the front whegs were to collide with intermediate whegs, risking to block the robot in tight corners.
The addition of the coupling passive was necessary because of the length of LionHell and the difficulty that this had in making some curves
narrow, and the basic idea was to simulate, in some respects, the hook present in the trailers and in trains, with the difference that in this case also
the trailer is able to bend, thus facilitating the movement.

[[File:Central passive joint high.jpg|200px|Central passive joint of LionHell II]][[File:Central passive joint scheme.PNG|200px|Scheme of the central passive joint of LionHell II]][[File:Central passive joint left.jpg|200px|Central passive joint of LionHell II]]

<h3> <span class="mw-headline" id="Tail">Tail</span></h3>

LionHell II is a mobile robot that has to face obstacles of small and medium size, and sometimes finds himself forced to having to overcome obstacles
large. In order for this operation to be successful, it is necessary that the robot does not fall backwards because of repeated setbacks caused from
the movement of the whegs seeking a foothold on which to do strength and lift the rest of the body of the robot.

[[File:Tail side LionHell.png|300px|Previous tail of LionHell]][[File:Tail high LionHell.png|280px|Previous tail of LionHell]]

The addition of the tail ensures greater stability during the climbs and allows him to lift the body preventing the possibility of falling back.
The morphological characteristics that allow the robot to move with greater ease, also facing major obstacles, are:
<ul>
<li> two motors in position mode, which allow the tail to bend and to force the tip when its intervention is required; </li>
<li> the total length of the queue, proportional to the length of the body; </li>
<li> the response of the tail which operates only when the robot is preparing to face major obstacles, recognizable by sensors head. </li>
</ul>

[[File:Tail side LionHell II.jpg |300px|Tail of LionHell II]][[File:Tail high LionHell II.jpg|300px|Tail of LionHell II]]

Compared to the original design, the tail has been modified to intensify the robot and increase the effectiveness and the force with which the tail presses on
terrain, namely:
<ul>
<li> the structure of the queue has been reinforced, in order to avoid that the new tail is damaged over time because of the force developed by engines
and the same weight of the robot; </li>
<li> the strength of the joint that allows the new queue was moving increased, using two motors in parallel that allow LionHell II to move with greater
ease while facing large obstacles. </li>
</ul>

<h2> <span class="mw-headline" id="RC_LionHell_II">Remote Control in LionHell II</span></h2>

<h3> <span class="mw-headline" id="Remote_controller">Remote controller</span></h3>

The figure shows the basic components of the remote control (excluding
a button and the switch, which for practical reasons are not shown in
figure, being incorporated into the external structure of the remote control).
The remote control is made up of:
<ul>
<li> a 9 V battery and 250 mAh which is the power; </li>
<li> an XBee Explorer Regulated that deals with the tension adjustment 3.3V, the signal conditioning and the basic activity indicators
and converts the signals from 5V to 3.3V in order to connect the system to any XBee module; </li>
<li> an XBee 4214A which plays the role of transmitting the signals received in input and communicates to the XBee installed on the body of LionHell II; </li>
<li> a three-axis analog accelerometer ADXL335, with card detection +/- 3g devoid of voltage regulator (the input voltage must be between 1.8V and 3.6V dc); </li>
<li> a circuit breaker switch that plays the role of power switch ON and OFF; </li>
<li> a red button unstable normally open, which allows the use the remote control while pressing. </li>
</ul>
The movement of LionHell II is via the inclination of the remote control(pointing the tip of the magician's hat forward and with the red button
upwards the robot is stationary, while raising or lowering the hat you can make it go forwards or backwards, and tilting
the remote control to the right or the left, the robot rotates to the right or left, respectively), which detects a change of axes X and Y by means
the accelerometer. The values are then passed to the XBee installed on remote control, which sends them directly to the XBee on LionHell II.

[[File:Remote controller 1.jpg|200px]][[File:Remote controller components.PNG|400px]]

<h3> <span class="mw-headline" id="XBee_LionHell">XBee of LionHell II</span></h3>

The goal of the XBee is to receive data from the remote control and send the data so
received to the control board LionHell II, with the result that the control board doesn't notice
even the existence of the XBee, as if it is reading data directly from the
remote controller.

The figures show the XBee 4214A used LionHell II, mounted directly
above the control board CM-510, at the center of the body of the robot,
and the the components underlying the XBee. How it is possible to
observe, are present (for each of the two digital inputs) a resistance
and a capacitor: the reason is easily explained.
The data transmitted from the XBee of the remote controller to the XBee of LionHell II are in analog form, but the inputs
control board does not require a digital type wave
square (obtainable via an inverting gate NOT, a Schmitt trigger,
a capacitor and a resistor) but through a filter of low-pass type (which
only requires the use of an RC circuit, based precisely on the use
of a resistor and a dynamic element, the capacitor).

[[File:XBee LionHell II.jpg|200px]]
[[File:XBee below LionHell II.jpg|300px]]

<h3> <span class="mw-headline" id="firmware_movement">Changes to the firmware</span></h3>

Once the signal is started by the remote, it's been installed on the XBee
on LionHell II and has been suitably modified to return
the original values read initially by the accelerometer of the remote control,
it is the turn of the control board CM-510.
The board acts as if it reads the values directly from the accelerometer,
doesn't even notice the existence of all the intermediate components, and
discriminates on the basis of these values the actions to be taken. Below there is
code of LionHell II reading the accelerometer values:

<pre>
// Read Remote Controller via XBee using Virtual Wires
{
resultX = adc_start( 4 );
resultY = adc_start( 3 );
bRemoteButton = (PINE & BTN_RIGHT) ;
// printf( "\r \n resultX resultY button: %u %u %d " ,resultX, resultY , bRemoteButton ) ;
// BUTTON
if ( bRemoteButton )
{
walking = true ;
}
else
{
walking = false ;
}
//X
if ( resultX > 340 )
{
turnL = 0 ; turnR=0; // Go Fwd
} else
if ( resultX < 300 )
{
turnL = 1 ; turnR=1; // Go Bwd
}
//Y
if ( resultY > 340 )
{
turnR = 1 ; turnL=0; // Turn Right
} else
if ( resultY < 300 )
{
turnL = 1 ; turnR=0; // Turn Left
}
}
</pre>

The code shows a first reading of the values X and Y of the accelerometer,
saved in variables resultX and resultY, later
is read the value of the red button by the variable bRemoteButton.
In the case where the red button is pressed then the variable walking
is set to true and based on the values of resultX and
resultY is chosen the direction to take.
The following code shows the behaviour of LionHell
II after the reception of the signals of the accelerometer and after that has been chosen
the action to be performed:

<pre>
//Walking Actions
if ( walking==1){
if ( turnL && turnR) {
int i ;
for ( i =0; i <3; i++){//Go Backward
dxl_write_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 1624 ) ;
dxl_write_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 600 ) ;
}
} else
if ( turnL ) {//Turn Left
int i ;
for ( i =0; i <3; i++){
dxl_write_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 1624 ) ;
dxl_write_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 1624 ) ;
// dxl_wri te_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 0 ) ;
}
} else
if ( turnR) {//Turn Right
int i ;
for ( i =0; i <3; i++){
dxl_write_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 600 ) ;
// dxl_wri te_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 0 ) ;
dxl_write_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 600 ) ;
}
} else
if ( ! ( turnL + turnR) ) {// If not turning
go_fwd ( ) ; // Restart walking
}
} else {// Stop Walking
stop ( ) ;
}
</pre>

In this case the choice of moving LionHell II is exclusively based on the
values of walking , turnL (turn left) and turnR (turn right).
In the case in which the values of turnL and turnR are both zero, then LionHell
II continue straight (the function sets the speed dxl_write_word
movement of each Wheg and its direction). In the other two cases,
however, with the modifying of the values of turnL and turnR, the robot will make the decision
to turn left or right by modifying the speed and
directions of the whegs.

<h2> <span class="mw-headline" id="Design_Lionhell_II">Design of LionHell II</span></h2>

<h3> <span class="mw-headline" id="Face_Lionhell_II">Face of LionHell II</span></h3>

LionHell literally means "lion hell", also translated as
Hellish Lion. Consequently, it was a must try and give it a feline aspect,
despite the bar sensory very long which is the head of the robot.
For this reason it was chosen as an example the Royal Bengal tiger
(Panthera tigris tigris), the tiger more widespread and more common, because we had practical problems in trying to create a real crest
around the head.
The new face is made from a plastic material, very lightweight, which allows
beautify LionHell II without increment excessively the weight,
while the colors were applied using permanent markers, leaving
sufficient space for the central sensor (and this is the reason of the mouth
arc).

[[File:Face LionHell.jpg|900px]]

<h3> <span class="mw-headline" id="Remote_controller_Lionhell_II">Remote controller of LionHell II</span></h3>

LionHell II is controllable through the use of a remote control. To search
to make the remote control palatable to a wide audience, it was thought to
colour the remote control and add a classic wizard hat, blue
yellow stars.
The components of the remote control is enclosed in a tube of hard plastic,
covered by a yellow cardboard (from which emerge the switch and the button
red), the battery is removable from the rear of the remote control
while removing the cap and the rubber band below, you can extract
(with caution) the remaining members, and in particular the programmable XBee.
The hat is made in blue cardboard, while the stars were drawn
with an indelible yellow marker and the brim is reinforced internally with a
thin layer of aluminium.

[[File:Remote controller 1.jpg|180px]][[File:Remote controller 2.jpg|180px]]

<h3> <span class="mw-headline" id="Shell_Lionhell_II">Shell of LionHell II</span></h3>

LionHell II has been equipped with a metal structure, an shell aluminium,
to protect the body, and in particular the control card CM-510
and the delicate XBee from possible accidental falls, guaranteeing protection
solid and effective. The shell
consists of four overlapping semicircular plates, stuck one on the
other by some screws located at the bottom, while the interior was covered with
rubber in order to avoid a possible short circuit between the pins of the card
of the XBee that could accidentally come in contact with the shell.
In the figure we can also observe the presence of a screw smaller
large, in correspondence of the scale wider: it is the screw removal
of the shell (which is also available in a crank case
where the screw was tightened with excessive force), needed to be able to interact
with the control card CM-510 with the programming cable and to be able to
remove and reprogram the XBee.

[[File:Shell 1.jpg|200px]][[File:Shell 2.jpg|200px]]

<h3> <span class="mw-headline" id="power_button_Lionhell_II">Power button of LionHell II</span></h3>

The addition of the shell middle resulted in the inability to access
the power button unless you remove and replace the shell every
time. The solution was to mount a button stable normally
open to the top of the shell,
at the center of the robot.
The new button is directly connected to the control board CM-510
by means of the blue cable that is seen in the figure, allowing an easy access
and intuitive.

[[File:Power button 1.jpg|200px]][[File:Power button 2.jpg|300px]]

<h2> <span class="mw-headline" id="Experiments">Experiments</span></h2>

<br /><br />
{{#evp:youtube|KAUfXsc3kVs|LionHell McMillan II|center|600}}
<br /><br />

<h2> <span class="mw-headline" id="Downloads">Downloads</span></h2>

User Manual and Datasheet in Italian of LionHell McMillan II
<br />
[[Media:Manuale utente datasheet.pdf]]
<br /><br />
AVRGCC1.c file of LionHell McMillan II and GNU GPL license
<br />
[[Media:AVRGCC1 and GNU GPL license.zip]]
<br /><br />
"Atmel Studio 6.2" project of LionHell McMillan II with a README file and the GNU GPL license
<br />
[[Media:LionHell.zip]]
<br /><br />
For previous versions, refer to the page http://airlab.ws.dei.polimi.it/index.php/LionHell_McMillan
<br /><br />

LionHell McMillan II

2015-04-22T14:54:57Z

AlessandroRosina:

{{Project template
|title=LIONHELL MCMILLAN II: RIPROGETTAZIONE DI UN ROBOT ESAPODE BIOLOGICAMENTE ISPIRATO PER AREE MORFOLOGICAMENTE INSTABILI
|image=[[File:LionHell-image.jpg|200px|thumb|left|LionHell McMillan II]]
|description=Hexapode wheg robot
|tutor=Giuseppina Gini
|start=01/09/2014
|number=1
|cfu=20
}}

<p><br />
LionHell McMillan II is an hexapode wheg robot. LionHell McMillan has been developed in a Master Thesis work in Robotics and Artificial Intelligence by Vittorio Lumare ( http://airlab.ws.dei.polimi.it/index.php/LionHell_McMillan )
and it has been modified and improved in a Master Thesis work in Robotics and Artificial Intelligence by Alessandro Rosina (changing the name from "LionHell McMillan" to "LionHell McMillan II").
</p><p>Info about Thesis
</p>
<pre>TItle : LIONHELL MCMILLAN II: RIPROGETTAZIONE DI UN ROBOT ESAPODE BIOLOGICAMENTE ISPIRATO PER AREE MORFOLOGICAMENTE INSTABILI
Robot Name: LionHell McMillan II
Supervisor: Giuseppina Gini
Correlator: Vittorio Lumare
Author: Alessandro Rosina
Area: Robotics and Artifical Intelligence
Start date: 2014/09/10
End date: 2015/04/29
</pre>

[[File:LionHell-image.jpg|400px]][[File:LionHell II 2.jpg|400px]]
<br />
[[File:LionHell II 3.jpg|300px]][[File:LionHell II 4.jpg|400px]]

<h2> <span class="mw-headline" id="state_art">State of the Art</span></h2>
<h3> <span class="mw-headline" id="Wheg">Wheg</span></h3>

The locomotion system is the key element that allows the robot to
interface and explore the surrounding environment and requires a careful choice
that meets the requirements of handling, mechanical simplicity and fluidity
motion, ensuring, in this case, the possibility to move easily
on rough terrain, overcoming obstacles of small and medium
size.

<h4> <span class="mw-headline" id="Definition_Wheg">Definition of the Wheg</span></h4>

[[File:Description wheg.PNG|300px]][[File:Wheg 0 rotazione.PNG|600px]]

The Wheg are a mechanism of locomotion for robots that combine
simplicity of movement of a wheel with the ability to scale and to overcome
obstacles arising from the use of the legs. The acronym derives
by the combination of words wheel and leg and mechanically it
consists of a central rotary axis and which are connected one or more bars
which perform the function of the legs.
The operation of a Wheg is extremely simple: the three legs are connected to a central axis that rotates
on itself and the point of contact with the ground is made from the end
of the leg.

<h4> <span class="mw-headline" id="_vs_Wheel">Wheg vs Wheel</span></h4>

The superiority of Wheg comparison to the use of a simple wheel is easily
demonstrated:

[[File:Ruota1ostacoloPiccolo.png|300px]][[File:Ruota2ostacoloPiccolo.png|300px]][[File:Ruota3ostacoloPiccolo.png|300px]]

<ol>
<li> Consider a wheel that is about to face an obstacle placed on the floor, much smaller than the radius
the wheel itself; </li>
<li> Once the wheel comes into contact with the obstacle, the clutch
that is generated will force the point of contact to remain in the same
position and while the torsion of the wheel will continue to act, the point
contact will function as a pivot. If the power of the engine will be
enough the result will be that the wheel will walk across continuing
in its path; </li>
</ol>
[[File:Ruota1ostacoloGrande.png|500px]]
<ol>
<li>Now consider a similar situation, in which, however, the obstacle that
wheel must be facing the same overall height of its radius (h similar to r). In this case the contact point is on the side of the obstacle,
and not above as in the previous case and the clutch that you should
come and create so that it can be climbed should be such that
allow the robot to move in a vertical manner with respect to the obstacle.
Typically, this situation is not a realistic scenario and the
experiment result will be that the wheel will start to slip on the spot,
continuously changing the point of contact with the obstacle. Due to the fact
the wheel would fail in this scenario, the wheel would fail for all
scenarios where h > r as the contact point will always be on the
side of the obstacle and not above. </li>
</ol>

[[File:Wheg1ostacoloGrande.png|300px]][[File:Wheg2ostacoloGrande.png|300px]][[File:Wheg3ostacoloGrande.png|300px]]

Consider now the previous example, in which h is similar to r, but where in place
of the wheel there is a Wheg three legs (in figures can be
observe the presence of a circle around the Wheg: this circle is purely
illustrative and serves only to relate the size of Wheg
compared to those of the wheel):
<ol>
<li>First, you can see the huge gap that the structure
presents, space that will be used to your advantage: the structure
is in fact able to exploit the empty space, facing the obstacle
from above and not from the side as in the case of the wheel; </li>
<li>The force exerted by the engines and the twist of Wheg will do the rest,
allowing the exploitation of the point of contact as a pivot to raise the Wheg frame and overcome the obstacle (you
always remember that the circle only serves to show the trajectory
of the three legs); </li>
</ol>

[[File:Wheg1ostacoloEnorme.png|400px]]

<ol>
<li>Now consider another example, in
where we have h > r, and in particular the case in which h = 3/2 r (as
there are 3 legs). In this extreme case the Wheg will not be
able to overcome the obstacle: the ability to climb it depends on how the
Wheg is capable of penetrating the profile of the obstacle. You can get
this goal by reducing the angle between the two upper legs, but this
undermine the structure of Wheg making unstable. </li>
</ol>

From this analysis it is possible to highlight the main advantages and disadvantages
of using a Wheg:
<ul>
<li> Pro: the ability to climb obstacles of greater height than those
addressed by a wheel having the same radius; </li>
<li> Pro: the speed of movement of the robot is still high; </li>
<li> Pro: the greater simplicity of construction and control compared to
a leg, which must necessarily be controlled by two or
three actuators; </li>
<li> Cons: The land on which it moves must be rough, in order to
do strength and be able to overcome the obstacle; </li>
<li> Cons: Legs too thin could sink surfaces
soft or non-rigid, such as sand or mud, due to the
reduced contact surface; </li>
<li> Cons: If your legs hit moving parts, such as long grass or cables
very thin, the Wheg could be twisted, latching
and risking damage to the robot in the case where the motors
trying to do too much force to break free. </li>
</ul>

<h3> <span class="mw-headline" id="Wheg_robot">Robot with whegs</span></h3>

The Wheg is a system of locomotion used in many robot exploration, from Prolero, the first robot ever to be equipped
with Wheg, is a robot equipped initially with 4
Wheg and later of 1 to 6 Wheg leg, was developed by Martin
A. Alvarez, P. de Peuter, Hillebrand JR., P. Putz, Matthyssen A. and de Weerd
J. in 1996. Subsequently,
many other robots have followed his example:
<ul>
<li> Climbing Mini Whegs is a
robot with 4 Wheg each with 4 legs able to adhere to various surfaces,
was developed at Case Western Reserve University; </li>
<li> Embot is a robot equipped with 4 Wheg each with 3
legs, was developed at the Politecnico di Milano from Gaibotti
A. and F. Mariggiò in 2011; </li>
<li> Lunar Whegs is a robot equipped with
6 Wheg each with 3 legs, was developed by Dunker PA in 2009; </li>
<li> Mini-Whegs IV is a small robot
dimensions with 4 Wheg 3 legs, was developed by Morrey
J., B. Lambrecht, Horchler A., Ritzmann R. and R. Quinn in 2003; </li>
<li> OUTRUNNER is a robot equipped with 2 racing
Wheg each with 3 legs, was developed by S. Cotton, C. Black, Payton
N., K. Ford, and Howell W. Conrad, J. in 2014;</li>
<li> Ratasjalg is a robot equipped with only 2
Wheg each with 6 legs, which in case of need can become wheels,
was developed and patented by R. Sell at Tallinn University of
Technology in Estonia in 2007;</li>
<li> RHEX is a robot with 6 to Wheg
1 leg, was developed by Altendorfer R., N. Moore, Komsuoglu
H., M. Buehler, H. Brown Jr., McMordie D., Saranli U., R. and Full
Koditschek D in 2001;</li>
<li> Termes is a robot with 4 to Wheg
3 legs, was developed by Werfel J., K. Petersen, and R. Nagpal in
In 2014;</li>
<li> USAR Whegs is a robot equipped
4 Wheg 4 legs, was developed by AJ Hunt at Case
Western Reserve University in 2010.</li>
</ul>

<h2> <span class="mw-headline" id="CM_LionHell_II">Control and Mobility in LionHell II</span></h2>
<h3> <span class="mw-headline" id="Wheg_Lionhell_II">Wheg in LionHell II</span></h3>

[[File:Wheg LionHell.png|290px|right|Wheg of LionHell]]
[[File:Wheg LionHell II.png|300px|right|Wheg of LionHell II]]

The whegs are a mechanism of locomotion for robots that combine
simplicity of movement of a wheel with the ability to scale and to overcome obstacles arising from the use of the legs. The acronym derives
by the combination of words wheel and leg, and mechanically consist of a central rotary axis which are connected one or more bars
which perform the function of the legs. <br />
LionHell II has a total of 6 Wheg and each Wheg is composed of 3 bars arranged at 120° apart from each from the other, the ends of which is
mounted a foot slightly curved so as to ensure a secure grip on the ground. The movement of Wheg is simultaneous and each Wheg is controlled
by an independent motor that works in continuous mode, ensuring a smooth motion and robot suitable for every situation.
The Wheg that owns LionHell II is characterized by:
<ul>
<li> a structure baseline, aluminium, guarantees the point of contact with the central hub; </li>
<li> a basal structure of the foot, wood, molded according to an embodiment curve so as to adapt better to the ground and avoid jolts; </li>
<li> the foam, in contact with the foot structure, reduces shocks of the robot in contact with the ground; </li>
<li> rubber, in direct contact with the ground, protects the foam wear and allows the robot to move easily on any surface area; </li>
<li> the symbol allows to easily identify the components of the Wheg and position of the leg in the same robot; </li>
<li> the outline contour allows to understand intuitively the position with which the other members of Wheg be mounted. </li>
Compared to the previous model, we have kept the metal rod base and the rubber that was removed from the foot, since the movement of the same
LionHell would irreparably damaged the Wheg and in particular the delicate foothold.

<h3> <span class="mw-headline" id="Central_Passive_Joint">Central Passive Joint</span></h3>
This part will describe the role of the new central passive joint and the increase of the degrees of freedom that resulted.

<h4> <span class="mw-headline" id="DOF_LionHell_II">Degrees of Freedom of LionHell II</span></h4>
The number of degrees of freedom (DoF) of a material point is the number of independent variables needed to determine
uniquely its position in space (coordinates).
The degrees of freedom is a term used to define freedom of movement of a robot in the three spatial skills, and the
number of degrees of freedom of defining a robot configuration.
LionHell II is a hexapod robot equipped with Wheg, tail, a coupling motor that allows him to lift the front in order to better deal with
obstacles, and finally a central passive joint. In the figures you can
observe the degrees of freedom of LionHell II:
<ul>
<li> the movement of Wheg: each wheg has 1 degree of freedom, for a total of 6 degrees of freedom; </li>
<li> the movement of the joint motor and tail, each of which adds 1 degree of freedom, for a total of 2 degrees of freedom; </li>
<li> the central passive joint which was added later, and the green lines trace a possible movement of the front part of the robot. </li>
</ul>
The creation of a robot with a central joint in more passive arose from the idea to facilitate the movements when cornering and allow a more fluid
movement. In the next subsection we will explain in more detail the joint that has been added.

[[File:Dof wheg LionHell.PNG|300px|DoF of the whegs of LionHell II]][[File:Dof giunto LionHell.PNG|300px|DoF of the central passive joint of LionHell II]][[File:Dof testa coda LionHell.PNG|300px|DoF of the frontal part and of the tail of LionHell II]]

<h4> <span class="mw-headline" id="CPJ_LionHell_II">Central Passive Joint of LionHell II</span></h4>
LionHell II is equipped with a passive joint central, whose role is to accompany the movement of Wheg facilitating the movement when the
robot is going to bend. The passive coupling is constituted by:
<ul>
<li> a connecting member which allows rotation of a part of the body of LionHell II; </li>
<li> a pair of metal bars at the two ends of the connecting element, which are part of the security system; </li>
<li> two screws at the ends of the bars, their role is to define the angle of maximum rotation of the joint. </li>
</ul>
The screws may be replaced with shorter or longer, at difference if you want a rotation angle lower or higher. In
current state, the joint is able to rotate 10° to the right or to the left, while with the total absence of the screws the angle increases up to 30°. The addition
screw was necessary as it was presented the risk that the front whegs were to collide with intermediate whegs, risking to block the robot in tight corners.
The addition of the coupling passive was necessary because of the length of LionHell and the difficulty that this had in making some curves
narrow, and the basic idea was to simulate, in some respects, the hook present in the trailers and in trains, with the difference that in this case also
the trailer is able to bend, thus facilitating the movement.

[[File:Central passive joint high.jpg|200px|Central passive joint of LionHell II]][[File:Central passive joint scheme.PNG|200px|Scheme of the central passive joint of LionHell II]][[File:Central passive joint left.jpg|200px|Central passive joint of LionHell II]]

<h3> <span class="mw-headline" id="Tail">Tail</span></h3>

LionHell II is a mobile robot that has to face obstacles of small and medium size, and sometimes finds himself forced to having to overcome obstacles
large. In order for this operation to be successful, it is necessary that the robot does not fall backwards because of repeated setbacks caused from
the movement of the whegs seeking a foothold on which to do strength and lift the rest of the body of the robot.

[[File:Tail side LionHell.png|300px|Previous tail of LionHell]][[File:Tail high LionHell.png|280px|Previous tail of LionHell]]

The addition of the tail ensures greater stability during the climbs and allows him to lift the body preventing the possibility of falling back.
The morphological characteristics that allow the robot to move with greater ease, also facing major obstacles, are:
<ul>
<li> two motors in position mode, which allow the tail to bend and to force the tip when its intervention is required; </li>
<li> the total length of the queue, proportional to the length of the body; </li>
<li> the response of the tail which operates only when the robot is preparing to face major obstacles, recognizable by sensors head. </li>
</ul>

[[File:Tail side LionHell II.jpg |300px|Tail of LionHell II]][[File:Tail high LionHell II.jpg|300px|Tail of LionHell II]]

Compared to the original design, the tail has been modified to intensify the robot and increase the effectiveness and the force with which the tail presses on
terrain, namely:
<ul>
<li> the structure of the queue has been reinforced, in order to avoid that the new tail is damaged over time because of the force developed by engines
and the same weight of the robot; </li>
<li> the strength of the joint that allows the new queue was moving increased, using two motors in parallel that allow LionHell II to move with greater
ease while facing large obstacles. </li>
</ul>

<h2> <span class="mw-headline" id="RC_LionHell_II">Remote Control in LionHell II</span></h2>

<h3> <span class="mw-headline" id="Remote_controller">Remote controller</span></h3>

The figure shows the basic components of the remote control (excluding
a button and the switch, which for practical reasons are not shown in
figure, being incorporated into the external structure of the remote control).
The remote control is made up of:
<ul>
<li> a 9 V battery and 250 mAh which is the power; </li>
<li> an XBee Explorer Regulated that deals with the tension adjustment 3.3V, the signal conditioning and the basic activity indicators
and converts the signals from 5V to 3.3V in order to connect the system to any XBee module; </li>
<li> an XBee 4214A which plays the role of transmitting the signals received in input and communicates to the XBee installed on the body of LionHell II; </li>
<li> a three-axis analog accelerometer ADXL335, with card detection +/- 3g devoid of voltage regulator (the input voltage must be between 1.8V and 3.6V dc); </li>
<li> a circuit breaker switch that plays the role of power switch ON and OFF; </li>
<li> a red button unstable normally open, which allows the use the remote control while pressing. </li>
</ul>
The movement of LionHell II is via the inclination of the remote control(pointing the tip of the magician's hat forward and with the red button
upwards the robot is stationary, while raising or lowering the hat you can make it go forwards or backwards, and tilting
the remote control to the right or the left, the robot rotates to the right or left, respectively), which detects a change of axes X and Y by means
the accelerometer. The values are then passed to the XBee installed on remote control, which sends them directly to the XBee on LionHell II.

[[File:Remote controller 1.jpg|200px]][[File:Remote controller components.PNG|400px]]

<h3> <span class="mw-headline" id="XBee_LionHell">XBee of LionHell II</span></h3>

The goal of the XBee is to receive data from the remote control and send the data so
received to the control board LionHell II, with the result that the control board doesn't notice
even the existence of the XBee, as if it is reading data directly from the
remote controller.

The figures show the XBee 4214A used LionHell II, mounted directly
above the control board CM-510, at the center of the body of the robot,
and the the components underlying the XBee. How it is possible to
observe, are present (for each of the two digital inputs) a resistance
and a capacitor: the reason is easily explained.
The data transmitted from the XBee of the remote controller to the XBee of LionHell II are in analog form, but the inputs
control board does not require a digital type wave
square (obtainable via an inverting gate NOT, a Schmitt trigger,
a capacitor and a resistor) but through a filter of low-pass type (which
only requires the use of an RC circuit, based precisely on the use
of a resistor and a dynamic element, the capacitor).

[[File:XBee LionHell II.jpg|200px]]
[[File:XBee below LionHell II.jpg|300px]]

<h3> <span class="mw-headline" id="firmware_movement">Changes to the firmware</span></h3>

Once the signal is started by the remote, it's been installed on the XBee
on LionHell II and has been suitably modified to return
the original values read initially by the accelerometer of the remote control,
it is the turn of the control board CM-510.
The board acts as if it reads the values directly from the accelerometer,
doesn't even notice the existence of all the intermediate components, and
discriminates on the basis of these values the actions to be taken. Below there is
code of LionHell II reading the accelerometer values:

<pre>
// Read Remote Controller via XBee using Virtual Wires
{
resultX = adc_start( 4 );
resultY = adc_start( 3 );
bRemoteButton = (PINE & BTN_RIGHT) ;
// printf( "\r \n resultX resultY button: %u %u %d " ,resultX, resultY , bRemoteButton ) ;
// BUTTON
if ( bRemoteButton )
{
walking = true ;
}
else
{
walking = false ;
}
//X
if ( resultX > 340 )
{
turnL = 0 ; turnR=0; // Go Fwd
} else
if ( resultX < 300 )
{
turnL = 1 ; turnR=1; // Go Bwd
}
//Y
if ( resultY > 340 )
{
turnR = 1 ; turnL=0; // Turn Right
} else
if ( resultY < 300 )
{
turnL = 1 ; turnR=0; // Turn Left
}
}
</pre>

The code shows a first reading of the values X and Y of the accelerometer,
saved in variables resultX and resultY, later
is read the value of the red button by the variable bRemoteButton.
In the case where the red button is pressed then the variable walking
is set to true and based on the values of resultX and
resultY is chosen the direction to take.
The following code shows the behaviour of LionHell
II after the reception of the signals of the accelerometer and after that has been chosen
the action to be performed:

<pre>
//Walking Actions
if ( walking==1){
if ( turnL && turnR) {
int i ;
for ( i =0; i <3; i++){//Go Backward
dxl_write_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 1624 ) ;
dxl_write_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 600 ) ;
}
} else
if ( turnL ) {//Turn Left
int i ;
for ( i =0; i <3; i++){
dxl_write_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 1624 ) ;
dxl_write_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 1624 ) ;
// dxl_wri te_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 0 ) ;
}
} else
if ( turnR) {//Turn Right
int i ;
for ( i =0; i <3; i++){
dxl_write_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 600 ) ;
// dxl_wri te_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 0 ) ;
dxl_write_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 600 ) ;
}
} else
if ( ! ( turnL + turnR) ) {// If not turning
go_fwd ( ) ; // Restart walking
}
} else {// Stop Walking
stop ( ) ;
}
</pre>

In this case the choice of moving LionHell II is exclusively based on the
values of walking , turnL (turn left) and turnR (turn right).
In the case in which the values of turnL and turnR are both zero, then LionHell
II continue straight (the function sets the speed dxl_write_word
movement of each Wheg and its direction). In the other two cases,
however, with the modifying of the values of turnL and turnR, the robot will make the decision
to turn left or right by modifying the speed and
directions of the whegs.

<h2> <span class="mw-headline" id="Design_Lionhell_II">Design of LionHell II</span></h2>

<h3> <span class="mw-headline" id="Face_Lionhell_II">Face of LionHell II</span></h3>

LionHell literally means "lion hell", also translated as
Hellish Lion. Consequently, it was a must try and give it a feline aspect,
despite the bar sensory very long which is the head of the robot.
For this reason it was chosen as an example the Royal Bengal tiger
(Panthera tigris tigris), the tiger more widespread and more common, because we had practical problems in trying to create a real crest
around the head.
The new face is made from a plastic material, very lightweight, which allows
beautify LionHell II without increment excessively the weight,
while the colors were applied using permanent markers, leaving
sufficient space for the central sensor (and this is the reason of the mouth
arc).

[[File:Face LionHell.jpg|900px]]

<h3> <span class="mw-headline" id="Remote_controller_Lionhell_II">Remote controller of LionHell II</span></h3>

LionHell II is controllable through the use of a remote control. To search
to make the remote control palatable to a wide audience, it was thought to
colour the remote control and add a classic wizard hat, blue
yellow stars.
The components of the remote control is enclosed in a tube of hard plastic,
covered by a yellow cardboard (from which emerge the switch and the button
red), the battery is removable from the rear of the remote control
while removing the cap and the rubber band below, you can extract
(with caution) the remaining members, and in particular the programmable XBee.
The hat is made in blue cardboard, while the stars were drawn
with an indelible yellow marker and the brim is reinforced internally with a
thin layer of aluminium.

[[File:Remote controller 1.jpg|180px]][[File:Remote controller 2.jpg|180px]]

<h3> <span class="mw-headline" id="Shell_Lionhell_II">Shell of LionHell II</span></h3>

LionHell II has been equipped with a metal structure, an shell aluminium,
to protect the body, and in particular the control card CM-510
and the delicate XBee from possible accidental falls, guaranteeing protection
solid and effective. The shell
consists of four overlapping semicircular plates, stuck one on the
other by some screws located at the bottom, while the interior was covered with
rubber in order to avoid a possible short circuit between the pins of the card
of the XBee that could accidentally come in contact with the shell.
In the figure we can also observe the presence of a screw smaller
large, in correspondence of the scale wider: it is the screw removal
of the shell (which is also available in a crank case
where the screw was tightened with excessive force), needed to be able to interact
with the control card CM-510 with the programming cable and to be able to
remove and reprogram the XBee.

[[File:Shell 1.jpg|200px]][[File:Shell 2.jpg|200px]]

<h3> <span class="mw-headline" id="power_button_Lionhell_II">Power button of LionHell II</span></h3>

The addition of the shell middle resulted in the inability to access
the power button unless you remove and replace the shell every
time. The solution was to mount a button stable normally
open to the top of the shell,
at the center of the robot.
The new button is directly connected to the control board CM-510
by means of the blue cable that is seen in the figure, allowing an easy access
and intuitive.

[[File:Power button 1.jpg|200px]][[File:Power button 2.jpg|300px]]

<h2> <span class="mw-headline" id="Experiments">Experiments</span></h2>

<br /><br />
{{#evp:youtube|KAUfXsc3kVs|LionHell McMillan II|center|600}}
<br /><br />

<h2> <span class="mw-headline" id="Downloads">Downloads</span></h2>

User Manual and Datasheet in Italian of LionHell McMillan II
<br />
[[Media:Manuale utente datasheet.pdf]]
<br /><br />
AVRGCC1.c file of LionHell McMillan II and GNU GPL license
<br />
[[Media:AVRGCC1 and GNU GPL license.zip]]
<br /><br />
"Atmel Studio 6.2" project of LionHell McMillan II with a README file and the GNU GPL license
<br />
[[Media:LionHell.zip]]
<br /><br />
For previous versions, refer to the page http://airlab.ws.dei.polimi.it/index.php/LionHell_McMillan
<br /><br />

LionHell McMillan II

2015-04-10T09:53:06Z

AlessandroRosina:

{{Project template
|title=LIONHELL MCMILLAN II: RIPROGETTAZIONE DI UN ROBOT ESAPODE BIOLOGICAMENTE ISPIRATO PER AREE MORFOLOGICAMENTE INSTABILI
|image=[[File:LionHell-image.jpg|200px|thumb|left|LionHell McMillan II]]
|description=Hexapode wheg robot
|tutor=Giuseppina Gini
|start=01/09/2014
|number=1
|cfu=20
}}
<font size="7">CHANGES IN PROGRESS</font>
<p><br />
LionHell McMillan II is an hexapode wheg robot. LionHell McMillan has been developed in a Master Thesis work in Robotics and Artificial Intelligence by Vittorio Lumare ( http://airlab.ws.dei.polimi.it/index.php/LionHell_McMillan )
and it has been modified and improved in a Master Thesis work in Robotics and Artificial Intelligence by Alessandro Rosina (changing the name from "LionHell McMillan" to "LionHell McMillan II").
</p><p>Info about Thesis
</p>
<pre>TItle : LIONHELL MCMILLAN II: RIPROGETTAZIONE DI UN ROBOT ESAPODE BIOLOGICAMENTE ISPIRATO PER AREE MORFOLOGICAMENTE INSTABILI
Robot Name: LionHell McMillan II
Supervisor: Giuseppina Gini
Correlator: Vittorio Lumare
Author: Alessandro Rosina
Area: Robotics and Artifical Intelligence
Start date: 2014/09/10
End date: 2015/04/29
</pre>

[[File:LionHell-image.jpg|400px]][[File:LionHell II 2.jpg|400px]]
<br />
[[File:LionHell II 3.jpg|300px]][[File:LionHell II 4.jpg|400px]]

<h2> <span class="mw-headline" id="state_art">State of the Art</span></h2>
<h3> <span class="mw-headline" id="Wheg">Wheg</span></h3>

The locomotion system is the key element that allows the robot to
interface and explore the surrounding environment and requires a careful choice
that meets the requirements of handling, mechanical simplicity and fluidity
motion, ensuring, in this case, the possibility to move easily
on rough terrain, overcoming obstacles of small and medium
size.

<h4> <span class="mw-headline" id="Definition_Wheg">Definition of the Wheg</span></h4>

[[File:Description wheg.PNG|300px]][[File:Wheg 0 rotazione.PNG|600px]]

The Wheg are a mechanism of locomotion for robots that combine
simplicity of movement of a wheel with the ability to scale and to overcome
obstacles arising from the use of the legs. The acronym derives
by the combination of words wheel and leg and mechanically it
consists of a central rotary axis and which are connected one or more bars
which perform the function of the legs.
The operation of a Wheg is extremely simple: the three legs are connected to a central axis that rotates
on itself and the point of contact with the ground is made from the end
of the leg.

<h4> <span class="mw-headline" id="_vs_Wheel">Wheg vs Wheel</span></h4>

The superiority of Wheg comparison to the use of a simple wheel is easily
demonstrated:

[[File:Ruota1ostacoloPiccolo.png|300px]][[File:Ruota2ostacoloPiccolo.png|300px]][[File:Ruota3ostacoloPiccolo.png|300px]]

<ol>
<li> Consider a wheel that is about to face an obstacle placed on the floor, much smaller than the radius
the wheel itself; </li>
<li> Once the wheel comes into contact with the obstacle, the clutch
that is generated will force the point of contact to remain in the same
position and while the torsion of the wheel will continue to act, the point
contact will function as a pivot. If the power of the engine will be
enough the result will be that the wheel will walk across continuing
in its path; </li>
</ol>
[[File:Ruota1ostacoloGrande.png|500px]]
<ol>
<li>Now consider a similar situation, in which, however, the obstacle that
wheel must be facing the same overall height of its radius (h similar to r). In this case the contact point is on the side of the obstacle,
and not above as in the previous case and the clutch that you should
come and create so that it can be climbed should be such that
allow the robot to move in a vertical manner with respect to the obstacle.
Typically, this situation is not a realistic scenario and the
experiment result will be that the wheel will start to slip on the spot,
continuously changing the point of contact with the obstacle. Due to the fact
the wheel would fail in this scenario, the wheel would fail for all
scenarios where h > r as the contact point will always be on the
side of the obstacle and not above. </li>
</ol>

[[File:Wheg1ostacoloGrande.png|300px]][[File:Wheg2ostacoloGrande.png|300px]][[File:Wheg3ostacoloGrande.png|300px]]

Consider now the previous example, in which h is similar to r, but where in place
of the wheel there is a Wheg three legs (in figures can be
observe the presence of a circle around the Wheg: this circle is purely
illustrative and serves only to relate the size of Wheg
compared to those of the wheel):
<ol>
<li>First, you can see the huge gap that the structure
presents, space that will be used to your advantage: the structure
is in fact able to exploit the empty space, facing the obstacle
from above and not from the side as in the case of the wheel; </li>
<li>The force exerted by the engines and the twist of Wheg will do the rest,
allowing the exploitation of the point of contact as a pivot to raise the Wheg frame and overcome the obstacle (you
always remember that the circle only serves to show the trajectory
of the three legs); </li>
</ol>

[[File:Wheg1ostacoloEnorme.png|400px]]

<ol>
<li>Now consider another example, in
where we have h > r, and in particular the case in which h = 3/2 r (as
there are 3 legs). In this extreme case the Wheg will not be
able to overcome the obstacle: the ability to climb it depends on how the
Wheg is capable of penetrating the profile of the obstacle. You can get
this goal by reducing the angle between the two upper legs, but this
undermine the structure of Wheg making unstable. </li>
</ol>

From this analysis it is possible to highlight the main advantages and disadvantages
of using a Wheg:
<ul>
<li> Pro: the ability to climb obstacles of greater height than those
addressed by a wheel having the same radius; </li>
<li> Pro: the speed of movement of the robot is still high; </li>
<li> Pro: the greater simplicity of construction and control compared to
a leg, which must necessarily be controlled by two or
three actuators; </li>
<li> Cons: The land on which it moves must be rough, in order to
do strength and be able to overcome the obstacle; </li>
<li> Cons: Legs too thin could sink surfaces
soft or non-rigid, such as sand or mud, due to the
reduced contact surface; </li>
<li> Cons: If your legs hit moving parts, such as long grass or cables
very thin, the Wheg could be twisted, latching
and risking damage to the robot in the case where the motors
trying to do too much force to break free. </li>
</ul>

<h3> <span class="mw-headline" id="Wheg_robot">Robot with whegs</span></h3>

The Wheg is a system of locomotion used in many robot exploration, from Prolero, the first robot ever to be equipped
with Wheg, is a robot equipped initially with 4
Wheg and later of 1 to 6 Wheg leg, was developed by Martin
A. Alvarez, P. de Peuter, Hillebrand JR., P. Putz, Matthyssen A. and de Weerd
J. in 1996. Subsequently,
many other robots have followed his example:
<ul>
<li> Climbing Mini Whegs is a
robot with 4 Wheg each with 4 legs able to adhere to various surfaces,
was developed at Case Western Reserve University; </li>
<li> Embot is a robot equipped with 4 Wheg each with 3
legs, was developed at the Politecnico di Milano from Gaibotti
A. and F. Mariggiò in 2011; </li>
<li> Lunar Whegs is a robot equipped with
6 Wheg each with 3 legs, was developed by Dunker PA in 2009; </li>
<li> Mini-Whegs IV is a small robot
dimensions with 4 Wheg 3 legs, was developed by Morrey
J., B. Lambrecht, Horchler A., Ritzmann R. and R. Quinn in 2003; </li>
<li> OUTRUNNER is a robot equipped with 2 racing
Wheg each with 3 legs, was developed by S. Cotton, C. Black, Payton
N., K. Ford, and Howell W. Conrad, J. in 2014;</li>
<li> Ratasjalg is a robot equipped with only 2
Wheg each with 6 legs, which in case of need can become wheels,
was developed and patented by R. Sell at Tallinn University of
Technology in Estonia in 2007;</li>
<li> RHEX is a robot with 6 to Wheg
1 leg, was developed by Altendorfer R., N. Moore, Komsuoglu
H., M. Buehler, H. Brown Jr., McMordie D., Saranli U., R. and Full
Koditschek D in 2001;</li>
<li> Termes is a robot with 4 to Wheg
3 legs, was developed by Werfel J., K. Petersen, and R. Nagpal in
In 2014;</li>
<li> USAR Whegs is a robot equipped
4 Wheg 4 legs, was developed by AJ Hunt at Case
Western Reserve University in 2010.</li>
</ul>

<h2> <span class="mw-headline" id="CM_LionHell_II">Control and Mobility in LionHell II</span></h2>
<h3> <span class="mw-headline" id="Wheg_Lionhell_II">Wheg in LionHell II</span></h3>

[[File:Wheg LionHell.png|290px|right|Wheg of LionHell]]
[[File:Wheg LionHell II.png|300px|right|Wheg of LionHell II]]

The whegs are a mechanism of locomotion for robots that combine
simplicity of movement of a wheel with the ability to scale and to overcome obstacles arising from the use of the legs. The acronym derives
by the combination of words wheel and leg, and mechanically consist of a central rotary axis which are connected one or more bars
which perform the function of the legs. <br />
LionHell II has a total of 6 Wheg and each Wheg is composed of 3 bars arranged at 120° apart from each from the other, the ends of which is
mounted a foot slightly curved so as to ensure a secure grip on the ground. The movement of Wheg is simultaneous and each Wheg is controlled
by an independent motor that works in continuous mode, ensuring a smooth motion and robot suitable for every situation.
The Wheg that owns LionHell II is characterized by:
<ul>
<li> a structure baseline, aluminium, guarantees the point of contact with the central hub; </li>
<li> a basal structure of the foot, wood, molded according to an embodiment curve so as to adapt better to the ground and avoid jolts; </li>
<li> the foam, in contact with the foot structure, reduces shocks of the robot in contact with the ground; </li>
<li> rubber, in direct contact with the ground, protects the foam wear and allows the robot to move easily on any surface area; </li>
<li> the symbol allows to easily identify the components of the Wheg and position of the leg in the same robot; </li>
<li> the outline contour allows to understand intuitively the position with which the other members of Wheg be mounted. </li>
Compared to the previous model, we have kept the metal rod base and the rubber that was removed from the foot, since the movement of the same
LionHell would irreparably damaged the Wheg and in particular the delicate foothold.

<h3> <span class="mw-headline" id="Central_Passive_Joint">Central Passive Joint</span></h3>
This part will describe the role of the new central passive joint and the increase of the degrees of freedom that resulted.

<h4> <span class="mw-headline" id="DOF_LionHell_II">Degrees of Freedom of LionHell II</span></h4>
The number of degrees of freedom (DoF) of a material point is the number of independent variables needed to determine
uniquely its position in space (coordinates).
The degrees of freedom is a term used to define freedom of movement of a robot in the three spatial skills, and the
number of degrees of freedom of defining a robot configuration.
LionHell II is a hexapod robot equipped with Wheg, tail, a coupling motor that allows him to lift the front in order to better deal with
obstacles, and finally a central passive joint. In the figures you can
observe the degrees of freedom of LionHell II:
<ul>
<li> the movement of Wheg: each wheg has 1 degree of freedom, for a total of 6 degrees of freedom; </li>
<li> the movement of the joint motor and tail, each of which adds 1 degree of freedom, for a total of 2 degrees of freedom; </li>
<li> the central passive joint which was added later, and the green lines trace a possible movement of the front part of the robot. </li>
</ul>
The creation of a robot with a central joint in more passive arose from the idea to facilitate the movements when cornering and allow a more fluid
movement. In the next subsection we will explain in more detail the joint that has been added.

[[File:Dof wheg LionHell.PNG|300px|DoF of the whegs of LionHell II]][[File:Dof giunto LionHell.PNG|300px|DoF of the central passive joint of LionHell II]][[File:Dof testa coda LionHell.PNG|300px|DoF of the frontal part and of the tail of LionHell II]]

<h4> <span class="mw-headline" id="CPJ_LionHell_II">Central Passive Joint of LionHell II</span></h4>
LionHell II is equipped with a passive joint central, whose role is to accompany the movement of Wheg facilitating the movement when the
robot is going to bend. The passive coupling is constituted by:
<ul>
<li> a connecting member which allows rotation of a part of the body of LionHell II; </li>
<li> a pair of metal bars at the two ends of the connecting element, which are part of the security system; </li>
<li> two screws at the ends of the bars, their role is to define the angle of maximum rotation of the joint. </li>
</ul>
The screws may be replaced with shorter or longer, at difference if you want a rotation angle lower or higher. In
current state, the joint is able to rotate 10° to the right or to the left, while with the total absence of the screws the angle increases up to 30°. The addition
screw was necessary as it was presented the risk that the front whegs were to collide with intermediate whegs, risking to block the robot in tight corners.
The addition of the coupling passive was necessary because of the length of LionHell and the difficulty that this had in making some curves
narrow, and the basic idea was to simulate, in some respects, the hook present in the trailers and in trains, with the difference that in this case also
the trailer is able to bend, thus facilitating the movement.

[[File:Central passive joint high.jpg|200px|Central passive joint of LionHell II]][[File:Central passive joint scheme.PNG|200px|Scheme of the central passive joint of LionHell II]][[File:Central passive joint left.jpg|200px|Central passive joint of LionHell II]]

<h3> <span class="mw-headline" id="Tail">Tail</span></h3>

LionHell II is a mobile robot that has to face obstacles of small and medium size, and sometimes finds himself forced to having to overcome obstacles
large. In order for this operation to be successful, it is necessary that the robot does not fall backwards because of repeated setbacks caused from
the movement of the whegs seeking a foothold on which to do strength and lift the rest of the body of the robot.

[[File:Tail side LionHell.png|300px|Previous tail of LionHell]][[File:Tail high LionHell.png|280px|Previous tail of LionHell]]

The addition of the tail ensures greater stability during the climbs and allows him to lift the body preventing the possibility of falling back.
The morphological characteristics that allow the robot to move with greater ease, also facing major obstacles, are:
<ul>
<li> two motors in position mode, which allow the tail to bend and to force the tip when its intervention is required; </li>
<li> the total length of the queue, proportional to the length of the body; </li>
<li> the response of the tail which operates only when the robot is preparing to face major obstacles, recognizable by sensors head. </li>
</ul>

[[File:Tail side LionHell II.jpg |300px|Tail of LionHell II]][[File:Tail high LionHell II.jpg|300px|Tail of LionHell II]]

Compared to the original design, the tail has been modified to intensify the robot and increase the effectiveness and the force with which the tail presses on
terrain, namely:
<ul>
<li> the structure of the queue has been reinforced, in order to avoid that the new tail is damaged over time because of the force developed by engines
and the same weight of the robot; </li>
<li> the strength of the joint that allows the new queue was moving increased, using two motors in parallel that allow LionHell II to move with greater
ease while facing large obstacles. </li>
</ul>

<h2> <span class="mw-headline" id="RC_LionHell_II">Remote Control in LionHell II</span></h2>

<h3> <span class="mw-headline" id="Remote_controller">Remote controller</span></h3>

The figure shows the basic components of the remote control (excluding
a button and the switch, which for practical reasons are not shown in
figure, being incorporated into the external structure of the remote control).
The remote control is made up of:
<ul>
<li> a 9 V battery and 250 mAh which is the power; </li>
<li> an XBee Explorer Regulated that deals with the tension adjustment 3.3V, the signal conditioning and the basic activity indicators
and converts the signals from 5V to 3.3V in order to connect the system to any XBee module; </li>
<li> an XBee 4214A which plays the role of transmitting the signals received in input and communicates to the XBee installed on the body of LionHell II; </li>
<li> a three-axis analog accelerometer ADXL335, with card detection +/- 3g devoid of voltage regulator (the input voltage must be between 1.8V and 3.6V dc); </li>
<li> a circuit breaker switch that plays the role of power switch ON and OFF; </li>
<li> a red button unstable normally open, which allows the use the remote control while pressing. </li>
</ul>
The movement of LionHell II is via the inclination of the remote control(pointing the tip of the magician's hat forward and with the red button
upwards the robot is stationary, while raising or lowering the hat you can make it go forwards or backwards, and tilting
the remote control to the right or the left, the robot rotates to the right or left, respectively), which detects a change of axes X and Y by means
the accelerometer. The values are then passed to the XBee installed on remote control, which sends them directly to the XBee on LionHell II.

[[File:Remote controller 1.jpg|200px]][[File:Remote controller components.PNG|400px]]

<h3> <span class="mw-headline" id="XBee_LionHell">XBee of LionHell II</span></h3>

The goal of the XBee is to receive data from the remote control and send the data so
received to the control board LionHell II, with the result that the control board doesn't notice
even the existence of the XBee, as if it is reading data directly from the
remote controller.

The figures show the XBee 4214A used LionHell II, mounted directly
above the control board CM-510, at the center of the body of the robot,
and the the components underlying the XBee. How it is possible to
observe, are present (for each of the two digital inputs) a resistance
and a capacitor: the reason is easily explained.
The data transmitted from the XBee of the remote controller to the XBee of LionHell II are in analog form, but the inputs
control board does not require a digital type wave
square (obtainable via an inverting gate NOT, a Schmitt trigger,
a capacitor and a resistor) but through a filter of low-pass type (which
only requires the use of an RC circuit, based precisely on the use
of a resistor and a dynamic element, the capacitor).

[[File:XBee LionHell II.jpg|200px]]
[[File:XBee below LionHell II.jpg|300px]]

<h3> <span class="mw-headline" id="firmware_movement">Changes to the firmware</span></h3>

Once the signal is started by the remote, it's been installed on the XBee
on LionHell II and has been suitably modified to return
the original values read initially by the accelerometer of the remote control,
it is the turn of the control board CM-510.
The board acts as if it reads the values directly from the accelerometer,
doesn't even notice the existence of all the intermediate components, and
discriminates on the basis of these values the actions to be taken. Below there is
code of LionHell II reading the accelerometer values:

<pre>
// Read Remote Controller via XBee using Virtual Wires
{
resultX = adc_start( 4 );
resultY = adc_start( 3 );
bRemoteButton = (PINE & BTN_RIGHT) ;
// printf( "\r \n resultX resultY button: %u %u %d " ,resultX, resultY , bRemoteButton ) ;
// BUTTON
if ( bRemoteButton )
{
walking = true ;
}
else
{
walking = false ;
}
//X
if ( resultX > 340 )
{
turnL = 0 ; turnR=0; // Go Fwd
} else
if ( resultX < 300 )
{
turnL = 1 ; turnR=1; // Go Bwd
}
//Y
if ( resultY > 340 )
{
turnR = 1 ; turnL=0; // Turn Right
} else
if ( resultY < 300 )
{
turnL = 1 ; turnR=0; // Turn Left
}
}
</pre>

The code shows a first reading of the values X and Y of the accelerometer,
saved in variables resultX and resultY, later
is read the value of the red button by the variable bRemoteButton.
In the case where the red button is pressed then the variable walking
is set to true and based on the values of resultX and
resultY is chosen the direction to take.
The following code shows the behaviour of LionHell
II after the reception of the signals of the accelerometer and after that has been chosen
the action to be performed:

<pre>
//Walking Actions
if ( walking==1){
if ( turnL && turnR) {
int i ;
for ( i =0; i <3; i++){//Go Backward
dxl_write_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 1624 ) ;
dxl_write_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 600 ) ;
}
} else
if ( turnL ) {//Turn Left
int i ;
for ( i =0; i <3; i++){
dxl_write_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 1624 ) ;
dxl_write_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 1624 ) ;
// dxl_wri te_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 0 ) ;
}
} else
if ( turnR) {//Turn Right
int i ;
for ( i =0; i <3; i++){
dxl_write_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 600 ) ;
// dxl_wri te_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 0 ) ;
dxl_write_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 600 ) ;
}
} else
if ( ! ( turnL + turnR) ) {// If not turning
go_fwd ( ) ; // Restart walking
}
} else {// Stop Walking
stop ( ) ;
}
</pre>

In this case the choice of moving LionHell II is exclusively based on the
values of walking , turnL (turn left) and turnR (turn right).
In the case in which the values of turnL and turnR are both zero, then LionHell
II continue straight (the function sets the speed dxl_write_word
movement of each Wheg and its direction). In the other two cases,
however, with the modifying of the values of turnL and turnR, the robot will make the decision
to turn left or right by modifying the speed and
directions of the whegs.

<h2> <span class="mw-headline" id="Design_Lionhell_II">Design of LionHell II</span></h2>

<h3> <span class="mw-headline" id="Face_Lionhell_II">Face of LionHell II</span></h3>

LionHell literally means "lion hell", also translated as
Hellish Lion. Consequently, it was a must try and give it a feline aspect,
despite the bar sensory very long which is the head of the robot.
For this reason it was chosen as an example the Royal Bengal tiger
(Panthera tigris tigris), the tiger more widespread and more common, because we had practical problems in trying to create a real crest
around the head.
The new face is made from a plastic material, very lightweight, which allows
beautify LionHell II without increment excessively the weight,
while the colors were applied using permanent markers, leaving
sufficient space for the central sensor (and this is the reason of the mouth
arc).

[[File:Face LionHell.jpg|900px]]

<h3> <span class="mw-headline" id="Remote_controller_Lionhell_II">Remote controller of LionHell II</span></h3>

LionHell II is controllable through the use of a remote control. To search
to make the remote control palatable to a wide audience, it was thought to
colour the remote control and add a classic wizard hat, blue
yellow stars.
The components of the remote control is enclosed in a tube of hard plastic,
covered by a yellow cardboard (from which emerge the switch and the button
red), the battery is removable from the rear of the remote control
while removing the cap and the rubber band below, you can extract
(with caution) the remaining members, and in particular the programmable XBee.
The hat is made in blue cardboard, while the stars were drawn
with an indelible yellow marker and the brim is reinforced internally with a
thin layer of aluminium.

[[File:Remote controller 1.jpg|180px]][[File:Remote controller 2.jpg|180px]]

<h3> <span class="mw-headline" id="Shell_Lionhell_II">Shell of LionHell II</span></h3>

LionHell II has been equipped with a metal structure, an shell aluminium,
to protect the body, and in particular the control card CM-510
and the delicate XBee from possible accidental falls, guaranteeing protection
solid and effective. The shell
consists of four overlapping semicircular plates, stuck one on the
other by some screws located at the bottom, while the interior was covered with
rubber in order to avoid a possible short circuit between the pins of the card
of the XBee that could accidentally come in contact with the shell.
In the figure we can also observe the presence of a screw smaller
large, in correspondence of the scale wider: it is the screw removal
of the shell (which is also available in a crank case
where the screw was tightened with excessive force), needed to be able to interact
with the control card CM-510 with the programming cable and to be able to
remove and reprogram the XBee.

[[File:Shell 1.jpg|200px]][[File:Shell 2.jpg|200px]]

<h3> <span class="mw-headline" id="power_button_Lionhell_II">Power button of LionHell II</span></h3>

The addition of the shell middle resulted in the inability to access
the power button unless you remove and replace the shell every
time. The solution was to mount a button stable normally
open to the top of the shell,
at the center of the robot.
The new button is directly connected to the control board CM-510
by means of the blue cable that is seen in the figure, allowing an easy access
and intuitive.

[[File:Power button 1.jpg|200px]][[File:Power button 2.jpg|300px]]

<h2> <span class="mw-headline" id="Experiments">Experiments</span></h2>

<h2> <span class="mw-headline" id="Downloads">Downloads</span></h2>

User Manual and Datasheet in Italian of LionHell McMillan II
<br />
[[Media:Manuale utente datasheet.pdf]]
<br /><br />
AVRGCC1.c file of LionHell McMillan II and GNU GPL license
<br />
[[Media:AVRGCC1 and GNU GPL license.zip]]
<br /><br />
"Atmel Studio 6.2" project of LionHell McMillan II with a README file and the GNU GPL license
<br />
[[Media:LionHell.zip]]
<br /><br />
For previous versions, refer to the page http://airlab.ws.dei.polimi.it/index.php/LionHell_McMillan
<br /><br />

File:Manuale utente datasheet.pdf

2015-04-10T09:39:37Z

AlessandroRosina: User Manual and Datasheet in Italian of LionHell McMillan II

User Manual and Datasheet in Italian of LionHell McMillan II

File:LionHell.zip

2015-04-10T09:36:14Z

AlessandroRosina: "Atmel Studio 6.2" project of LionHell McMillan II with a README file and the GNU GPL license

"Atmel Studio 6.2" project of LionHell McMillan II with a README file and the GNU GPL license

File:AVRGCC1 and GNU GPL license.zip

2015-04-10T09:30:29Z

AlessandroRosina: AVRGCC1 file of LionHell McMillan II and GNU GPL license

AVRGCC1 file of LionHell McMillan II and GNU GPL license

File:LionHell II 4.jpg

2015-04-10T09:13:29Z

AlessandroRosina: LionHell II

LionHell II

File:LionHell II 3.jpg

2015-04-10T08:56:59Z

AlessandroRosina: LionHell II

LionHell II

File:LionHell II 2.jpg

2015-04-10T08:45:04Z

AlessandroRosina: LionHell II

LionHell II

LionHell McMillan II

2015-04-08T16:58:24Z

AlessandroRosina:

{{Project template
|title=LIONHELL MCMILLAN II: RIPROGETTAZIONE DI UN ROBOT ESAPODE BIOLOGICAMENTE ISPIRATO PER AREE MORFOLOGICAMENTE INSTABILI
|image=[[File:LionHell-image.jpg|200px|thumb|left|LionHell McMillan II]]
|description=Hexapode wheg robot
|tutor=Giuseppina Gini
|start=01/09/2014
|number=1
|cfu=20
}}
<font size="7">CHANGES IN PROGRESS</font>
<p><br />
LionHell McMillan II is an hexapode wheg robot. LionHell McMillan has been developed in a Master Thesis work in Robotics and Artificial Intelligence by Vittorio Lumare ( http://airlab.ws.dei.polimi.it/index.php/LionHell_McMillan )
and it has been modified and improved in a Master Thesis work in Robotics and Artificial Intelligence by Alessandro Rosina (changing the name from "LionHell McMillan" to "LionHell McMillan II").
</p><p>Info about Thesis
</p>
<pre>TItle : LIONHELL MCMILLAN II: RIPROGETTAZIONE DI UN ROBOT ESAPODE BIOLOGICAMENTE ISPIRATO PER AREE MORFOLOGICAMENTE INSTABILI
Robot Name: LionHell McMillan II
Supervisor: Giuseppina Gini
Correlator: Vittorio Lumare
Author: Alessandro Rosina
Area: Robotics and Artifical Intelligence
Start date: 2014/09/10
End date: 2015/04/29
</pre>

<h2> <span class="mw-headline" id="state_art">State of the Art</span></h2>
<h3> <span class="mw-headline" id="Wheg">Wheg</span></h3>

The locomotion system is the key element that allows the robot to
interface and explore the surrounding environment and requires a careful choice
that meets the requirements of handling, mechanical simplicity and fluidity
motion, ensuring, in this case, the possibility to move easily
on rough terrain, overcoming obstacles of small and medium
size.

<h4> <span class="mw-headline" id="Definition_Wheg">Definition of the Wheg</span></h4>

[[File:Description wheg.PNG|300px]][[File:Wheg 0 rotazione.PNG|600px]]

The Wheg are a mechanism of locomotion for robots that combine
simplicity of movement of a wheel with the ability to scale and to overcome
obstacles arising from the use of the legs. The acronym derives
by the combination of words wheel and leg and mechanically it
consists of a central rotary axis and which are connected one or more bars
which perform the function of the legs.
The operation of a Wheg is extremely simple: the three legs are connected to a central axis that rotates
on itself and the point of contact with the ground is made from the end
of the leg.

<h4> <span class="mw-headline" id="_vs_Wheel">Wheg vs Wheel</span></h4>

The superiority of Wheg comparison to the use of a simple wheel is easily
demonstrated:

[[File:Ruota1ostacoloPiccolo.png|300px]][[File:Ruota2ostacoloPiccolo.png|300px]][[File:Ruota3ostacoloPiccolo.png|300px]]

<ol>
<li> Consider a wheel that is about to face an obstacle placed on the floor, much smaller than the radius
the wheel itself; </li>
<li> Once the wheel comes into contact with the obstacle, the clutch
that is generated will force the point of contact to remain in the same
position and while the torsion of the wheel will continue to act, the point
contact will function as a pivot. If the power of the engine will be
enough the result will be that the wheel will walk across continuing
in its path; </li>
</ol>
[[File:Ruota1ostacoloGrande.png|500px]]
<ol>
<li>Now consider a similar situation, in which, however, the obstacle that
wheel must be facing the same overall height of its radius (h similar to r). In this case the contact point is on the side of the obstacle,
and not above as in the previous case and the clutch that you should
come and create so that it can be climbed should be such that
allow the robot to move in a vertical manner with respect to the obstacle.
Typically, this situation is not a realistic scenario and the
experiment result will be that the wheel will start to slip on the spot,
continuously changing the point of contact with the obstacle. Due to the fact
the wheel would fail in this scenario, the wheel would fail for all
scenarios where h > r as the contact point will always be on the
side of the obstacle and not above. </li>
</ol>

[[File:Wheg1ostacoloGrande.png|300px]][[File:Wheg1ostacoloGrande.png|300px]][[File:Wheg1ostacoloGrande.png|300px]]

Consider now the previous example, in which h is similar to r, but where in place
of the wheel there is a Wheg three legs (in figures can be
observe the presence of a circle around the Wheg: this circle is purely
illustrative and serves only to relate the size of Wheg
compared to those of the wheel):
<ol>
<li>First, you can see the huge gap that the structure
presents, space that will be used to your advantage: the structure
is in fact able to exploit the empty space, facing the obstacle
from above and not from the side as in the case of the wheel; </li>
<li>The force exerted by the engines and the twist of Wheg will do the rest,
allowing the exploitation of the point of contact as a pivot to raise the Wheg frame and overcome the obstacle (you
always remember that the circle only serves to show the trajectory
of the three legs); </li>
</ol>

[[File:Wheg1ostacoloEnorme.png|400px]]

<ol>
<li>Now consider another example, in
where we have h > r, and in particular the case in which h = 3/2 r (as
there are 3 legs). In this extreme case the Wheg will not be
able to overcome the obstacle: the ability to climb it depends on how the
Wheg is capable of penetrating the profile of the obstacle. You can get
this goal by reducing the angle between the two upper legs, but this
undermine the structure of Wheg making unstable. </li>
</ol>

From this analysis it is possible to highlight the main advantages and disadvantages
of using a Wheg:
<ul>
<li> Pro: the ability to climb obstacles of greater height than those
addressed by a wheel having the same radius; </li>
<li> Pro: the speed of movement of the robot is still high; </li>
<li> Pro: the greater simplicity of construction and control compared to
a leg, which must necessarily be controlled by two or
three actuators; </li>
<li> Cons: The land on which it moves must be rough, in order to
do strength and be able to overcome the obstacle; </li>
<li> Cons: Legs too thin could sink surfaces
soft or non-rigid, such as sand or mud, due to the
reduced contact surface; </li>
<li> Cons: If your legs hit moving parts, such as long grass or cables
very thin, the Wheg could be twisted, latching
and risking damage to the robot in the case where the motors
trying to do too much force to break free. </li>
</ul>

<h3> <span class="mw-headline" id="Wheg_robot">Robot with whegs</span></h3>

The Wheg is a system of locomotion used in many robot exploration, from Prolero, the first robot ever to be equipped
with Wheg, is a robot equipped initially with 4
Wheg and later of 1 to 6 Wheg leg, was developed by Martin
A. Alvarez, P. de Peuter, Hillebrand JR., P. Putz, Matthyssen A. and de Weerd
J. in 1996. Subsequently,
many other robots have followed his example:
<ul>
<li> Climbing Mini Whegs is a
robot with 4 Wheg each with 4 legs able to adhere to various surfaces,
was developed at Case Western Reserve University; </li>
<li> Embot is a robot equipped with 4 Wheg each with 3
legs, was developed at the Politecnico di Milano from Gaibotti
A. and F. Mariggiò in 2011; </li>
<li> Lunar Whegs is a robot equipped with
6 Wheg each with 3 legs, was developed by Dunker PA in 2009; </li>
<li> Mini-Whegs IV is a small robot
dimensions with 4 Wheg 3 legs, was developed by Morrey
J., B. Lambrecht, Horchler A., Ritzmann R. and R. Quinn in 2003; </li>
<li> OUTRUNNER is a robot equipped with 2 racing
Wheg each with 3 legs, was developed by S. Cotton, C. Black, Payton
N., K. Ford, and Howell W. Conrad, J. in 2014;</li>
<li> Ratasjalg is a robot equipped with only 2
Wheg each with 6 legs, which in case of need can become wheels,
was developed and patented by R. Sell at Tallinn University of
Technology in Estonia in 2007;</li>
<li> RHEX is a robot with 6 to Wheg
1 leg, was developed by Altendorfer R., N. Moore, Komsuoglu
H., M. Buehler, H. Brown Jr., McMordie D., Saranli U., R. and Full
Koditschek D in 2001;</li>
<li> Termes is a robot with 4 to Wheg
3 legs, was developed by Werfel J., K. Petersen, and R. Nagpal in
In 2014;</li>
<li> USAR Whegs is a robot equipped
4 Wheg 4 legs, was developed by AJ Hunt at Case
Western Reserve University in 2010.</li>
</ul>

<h2> <span class="mw-headline" id="CM_LionHell_II">Control and Mobility in LionHell II</span></h2>
<h3> <span class="mw-headline" id="Wheg_Lionhell_II">Wheg in LionHell II</span></h3>

[[File:Wheg LionHell.png|290px|right|Wheg of LionHell]]
[[File:Wheg LionHell II.png|300px|right|Wheg of LionHell II]]

The whegs are a mechanism of locomotion for robots that combine
simplicity of movement of a wheel with the ability to scale and to overcome obstacles arising from the use of the legs. The acronym derives
by the combination of words wheel and leg, and mechanically consist of a central rotary axis which are connected one or more bars
which perform the function of the legs. <br />
LionHell II has a total of 6 Wheg and each Wheg is composed of 3 bars arranged at 120° apart from each from the other, the ends of which is
mounted a foot slightly curved so as to ensure a secure grip on the ground. The movement of Wheg is simultaneous and each Wheg is controlled
by an independent motor that works in continuous mode, ensuring a smooth motion and robot suitable for every situation.
The Wheg that owns LionHell II is characterized by:
<ul>
<li> a structure baseline, aluminium, guarantees the point of contact with the central hub; </li>
<li> a basal structure of the foot, wood, molded according to an embodiment curve so as to adapt better to the ground and avoid jolts; </li>
<li> the foam, in contact with the foot structure, reduces shocks of the robot in contact with the ground; </li>
<li> rubber, in direct contact with the ground, protects the foam wear and allows the robot to move easily on any surface area; </li>
<li> the symbol allows to easily identify the components of the Wheg and position of the leg in the same robot; </li>
<li> the outline contour allows to understand intuitively the position with which the other members of Wheg be mounted. </li>
Compared to the previous model, we have kept the metal rod base and the rubber that was removed from the foot, since the movement of the same
LionHell would irreparably damaged the Wheg and in particular the delicate foothold.

<h3> <span class="mw-headline" id="Central_Passive_Joint">Central Passive Joint</span></h3>
This part will describe the role of the new central passive joint and the increase of the degrees of freedom that resulted.

<h4> <span class="mw-headline" id="DOF_LionHell_II">Degrees of Freedom of LionHell II</span></h4>
The number of degrees of freedom (DoF) of a material point is the number of independent variables needed to determine
uniquely its position in space (coordinates).
The degrees of freedom is a term used to define freedom of movement of a robot in the three spatial skills, and the
number of degrees of freedom of defining a robot configuration.
LionHell II is a hexapod robot equipped with Wheg, tail, a coupling motor that allows him to lift the front in order to better deal with
obstacles, and finally a central passive joint. In the figures you can
observe the degrees of freedom of LionHell II:
<ul>
<li> the movement of Wheg: each wheg has 1 degree of freedom, for a total of 6 degrees of freedom; </li>
<li> the movement of the joint motor and tail, each of which adds 1 degree of freedom, for a total of 2 degrees of freedom; </li>
<li> the central passive joint which was added later, and the green lines trace a possible movement of the front part of the robot. </li>
</ul>
The creation of a robot with a central joint in more passive arose from the idea to facilitate the movements when cornering and allow a more fluid
movement. In the next subsection we will explain in more detail the joint that has been added.

[[File:Dof wheg LionHell.PNG|300px|DoF of the whegs of LionHell II]][[File:Dof giunto LionHell.PNG|300px|DoF of the central passive joint of LionHell II]][[File:Dof testa coda LionHell.PNG|300px|DoF of the frontal part and of the tail of LionHell II]]

<h4> <span class="mw-headline" id="CPJ_LionHell_II">Central Passive Joint of LionHell II</span></h4>
LionHell II is equipped with a passive joint central, whose role is to accompany the movement of Wheg facilitating the movement when the
robot is going to bend. The passive coupling is constituted by:
<ul>
<li> a connecting member which allows rotation of a part of the body of LionHell II; </li>
<li> a pair of metal bars at the two ends of the connecting element, which are part of the security system; </li>
<li> two screws at the ends of the bars, their role is to define the angle of maximum rotation of the joint. </li>
</ul>
The screws may be replaced with shorter or longer, at difference if you want a rotation angle lower or higher. In
current state, the joint is able to rotate 10° to the right or to the left, while with the total absence of the screws the angle increases up to 30°. The addition
screw was necessary as it was presented the risk that the front whegs were to collide with intermediate whegs, risking to block the robot in tight corners.
The addition of the coupling passive was necessary because of the length of LionHell and the difficulty that this had in making some curves
narrow, and the basic idea was to simulate, in some respects, the hook present in the trailers and in trains, with the difference that in this case also
the trailer is able to bend, thus facilitating the movement.

[[File:Central passive joint high.jpg|200px|Central passive joint of LionHell II]][[File:Central passive joint scheme.PNG|200px|Scheme of the central passive joint of LionHell II]][[File:Central passive joint left.jpg|200px|Central passive joint of LionHell II]]

<h3> <span class="mw-headline" id="Tail">Tail</span></h3>

LionHell II is a mobile robot that has to face obstacles of small and medium size, and sometimes finds himself forced to having to overcome obstacles
large. In order for this operation to be successful, it is necessary that the robot does not fall backwards because of repeated setbacks caused from
the movement of the whegs seeking a foothold on which to do strength and lift the rest of the body of the robot.

[[File:Tail side LionHell.png|300px|Previous tail of LionHell]][[File:Tail high LionHell.png|280px|Previous tail of LionHell]]

The addition of the tail ensures greater stability during the climbs and allows him to lift the body preventing the possibility of falling back.
The morphological characteristics that allow the robot to move with greater ease, also facing major obstacles, are:
<ul>
<li> two motors in position mode, which allow the tail to bend and to force the tip when its intervention is required; </li>
<li> the total length of the queue, proportional to the length of the body; </li>
<li> the response of the tail which operates only when the robot is preparing to face major obstacles, recognizable by sensors head. </li>
</ul>

[[File:Tail side LionHell II.jpg |300px|Tail of LionHell II]][[File:Tail high LionHell II.jpg|300px|Tail of LionHell II]]

Compared to the original design, the tail has been modified to intensify the robot and increase the effectiveness and the force with which the tail presses on
terrain, namely:
<ul>
<li> the structure of the queue has been reinforced, in order to avoid that the new tail is damaged over time because of the force developed by engines
and the same weight of the robot; </li>
<li> the strength of the joint that allows the new queue was moving increased, using two motors in parallel that allow LionHell II to move with greater
ease while facing large obstacles. </li>
</ul>

<h2> <span class="mw-headline" id="RC_LionHell_II">Remote Control in LionHell II</span></h2>

<h3> <span class="mw-headline" id="Remote_controller">Remote controller</span></h3>

The figure shows the basic components of the remote control (excluding
a button and the switch, which for practical reasons are not shown in
figure, being incorporated into the external structure of the remote control).
The remote control is made up of:
<ul>
<li> a 9 V battery and 250 mAh which is the power; </li>
<li> an XBee Explorer Regulated that deals with the tension adjustment 3.3V, the signal conditioning and the basic activity indicators
and converts the signals from 5V to 3.3V in order to connect the system to any XBee module; </li>
<li> an XBee 4214A which plays the role of transmitting the signals received in input and communicates to the XBee installed on the body of LionHell II; </li>
<li> a three-axis analog accelerometer ADXL335, with card detection +/- 3g devoid of voltage regulator (the input voltage must be between 1.8V and 3.6V dc); </li>
<li> a circuit breaker switch that plays the role of power switch ON and OFF; </li>
<li> a red button unstable normally open, which allows the use the remote control while pressing. </li>
</ul>
The movement of LionHell II is via the inclination of the remote control(pointing the tip of the magician's hat forward and with the red button
upwards the robot is stationary, while raising or lowering the hat you can make it go forwards or backwards, and tilting
the remote control to the right or the left, the robot rotates to the right or left, respectively), which detects a change of axes X and Y by means
the accelerometer. The values are then passed to the XBee installed on remote control, which sends them directly to the XBee on LionHell II.

[[File:Remote controller 1.jpg|200px]][[File:Remote controller components.PNG|400px]]

<h3> <span class="mw-headline" id="XBee_LionHell">XBee of LionHell II</span></h3>

The goal of the XBee is to receive data from the remote control and send the data so
received to the control board LionHell II, with the result that the control board doesn't notice
even the existence of the XBee, as if it is reading data directly from the
remote controller.

The figures show the XBee 4214A used LionHell II, mounted directly
above the control board CM-510, at the center of the body of the robot,
and the the components underlying the XBee. How it is possible to
observe, are present (for each of the two digital inputs) a resistance
and a capacitor: the reason is easily explained.
The data transmitted from the XBee of the remote controller to the XBee of LionHell II are in analog form, but the inputs
control board does not require a digital type wave
square (obtainable via an inverting gate NOT, a Schmitt trigger,
a capacitor and a resistor) but through a filter of low-pass type (which
only requires the use of an RC circuit, based precisely on the use
of a resistor and a dynamic element, the capacitor).

[[File:XBee LionHell II.jpg|200px]]
[[File:XBee below LionHell II.jpg|300px]]

<h3> <span class="mw-headline" id="firmware_movement">Changes to the firmware</span></h3>

Once the signal is started by the remote, it's been installed on the XBee
on LionHell II and has been suitably modified to return
the original values read initially by the accelerometer of the remote control,
it is the turn of the control board CM-510.
The board acts as if it reads the values directly from the accelerometer,
doesn't even notice the existence of all the intermediate components, and
discriminates on the basis of these values the actions to be taken. Below there is
code of LionHell II reading the accelerometer values:

<pre>
// Read Remote Controller via XBee using Virtual Wires
{
resultX = adc_start( 4 );
resultY = adc_start( 3 );
bRemoteButton = (PINE & BTN_RIGHT) ;
// printf( "\r \n resultX resultY button: %u %u %d " ,resultX, resultY , bRemoteButton ) ;
// BUTTON
if ( bRemoteButton )
{
walking = true ;
}
else
{
walking = false ;
}
//X
if ( resultX > 340 )
{
turnL = 0 ; turnR=0; // Go Fwd
} else
if ( resultX < 300 )
{
turnL = 1 ; turnR=1; // Go Bwd
}
//Y
if ( resultY > 340 )
{
turnR = 1 ; turnL=0; // Turn Right
} else
if ( resultY < 300 )
{
turnL = 1 ; turnR=0; // Turn Left
}
}
</pre>

The code shows a first reading of the values X and Y of the accelerometer,
saved in variables resultX and resultY, later
is read the value of the red button by the variable bRemoteButton.
In the case where the red button is pressed then the variable walking
is set to true and based on the values of resultX and
resultY is chosen the direction to take.
The following code shows the behaviour of LionHell
II after the reception of the signals of the accelerometer and after that has been chosen
the action to be performed:

<pre>
//Walking Actions
if ( walking==1){
if ( turnL && turnR) {
int i ;
for ( i =0; i <3; i++){//Go Backward
dxl_write_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 1624 ) ;
dxl_write_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 600 ) ;
}
} else
if ( turnL ) {//Turn Left
int i ;
for ( i =0; i <3; i++){
dxl_write_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 1624 ) ;
dxl_write_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 1624 ) ;
// dxl_wri te_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 0 ) ;
}
} else
if ( turnR) {//Turn Right
int i ;
for ( i =0; i <3; i++){
dxl_write_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 600 ) ;
// dxl_wri te_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 0 ) ;
dxl_write_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 600 ) ;
}
} else
if ( ! ( turnL + turnR) ) {// If not turning
go_fwd ( ) ; // Restart walking
}
} else {// Stop Walking
stop ( ) ;
}
</pre>

In this case the choice of moving LionHell II is exclusively based on the
values of walking , turnL (turn left) and turnR (turn right).
In the case in which the values of turnL and turnR are both zero, then LionHell
II continue straight (the function sets the speed dxl_write_word
movement of each Wheg and its direction). In the other two cases,
however, with the modifying of the values of turnL and turnR, the robot will make the decision
to turn left or right by modifying the speed and
directions of the whegs.

<h2> <span class="mw-headline" id="Design_Lionhell_II">Design of LionHell II</span></h2>

<h3> <span class="mw-headline" id="Face_Lionhell_II">Face of LionHell II</span></h3>

LionHell literally means "lion hell", also translated as
Hellish Lion. Consequently, it was a must try and give it a feline aspect,
despite the bar sensory very long which is the head of the robot.
For this reason it was chosen as an example the Royal Bengal tiger
(Panthera tigris tigris), the tiger more widespread and more common, because we had practical problems in trying to create a real crest
around the head.
The new face is made from a plastic material, very lightweight, which allows
beautify LionHell II without increment excessively the weight,
while the colors were applied using permanent markers, leaving
sufficient space for the central sensor (and this is the reason of the mouth
arc).

[[File:Face LionHell.jpg|900px]]

<h3> <span class="mw-headline" id="Remote_controller_Lionhell_II">Remote controller of LionHell II</span></h3>

LionHell II is controllable through the use of a remote control. To search
to make the remote control palatable to a wide audience, it was thought to
colour the remote control and add a classic wizard hat, blue
yellow stars.
The components of the remote control is enclosed in a tube of hard plastic,
covered by a yellow cardboard (from which emerge the switch and the button
red), the battery is removable from the rear of the remote control
while removing the cap and the rubber band below, you can extract
(with caution) the remaining members, and in particular the programmable XBee.
The hat is made in blue cardboard, while the stars were drawn
with an indelible yellow marker and the brim is reinforced internally with a
thin layer of aluminium.

[[File:Remote controller 1.jpg|180px]][[File:Remote controller 2.jpg|180px]]

<h3> <span class="mw-headline" id="Shell_Lionhell_II">Shell of LionHell II</span></h3>

LionHell II has been equipped with a metal structure, an shell aluminium,
to protect the body, and in particular the control card CM-510
and the delicate XBee from possible accidental falls, guaranteeing protection
solid and effective. The shell
consists of four overlapping semicircular plates, stuck one on the
other by some screws located at the bottom, while the interior was covered with
rubber in order to avoid a possible short circuit between the pins of the card
of the XBee that could accidentally come in contact with the shell.
In the figure we can also observe the presence of a screw smaller
large, in correspondence of the scale wider: it is the screw removal
of the shell (which is also available in a crank case
where the screw was tightened with excessive force), needed to be able to interact
with the control card CM-510 with the programming cable and to be able to
remove and reprogram the XBee.

[[File:Shell 1.jpg|200px]][[File:Shell 2.jpg|200px]]

<h3> <span class="mw-headline" id="power_button_Lionhell_II">Power button of LionHell II</span></h3>

The addition of the shell middle resulted in the inability to access
the power button unless you remove and replace the shell every
time. The solution was to mount a button stable normally
open to the top of the shell,
at the center of the robot.
The new button is directly connected to the control board CM-510
by means of the blue cable that is seen in the figure, allowing an easy access
and intuitive.

[[File:Power button 1.jpg|200px]][[File:Power button 2.jpg|300px]]

LionHell McMillan II

2015-04-08T16:25:05Z

AlessandroRosina:

{{Project template
|title=LIONHELL MCMILLAN II: RIPROGETTAZIONE DI UN ROBOT ESAPODE BIOLOGICAMENTE ISPIRATO PER AREE MORFOLOGICAMENTE INSTABILI
|image=[[File:LionHell-image.jpg|200px|thumb|left|LionHell McMillan II]]
|description=Hexapode wheg robot
|tutor=Giuseppina Gini
|start=01/09/2014
|number=1
|cfu=20
}}
<font size="7">CHANGES IN PROGRESS</font>
<p><br />
LionHell McMillan II is an hexapode wheg robot. LionHell McMillan has been developed in a Master Thesis work in Robotics and Artificial Intelligence by Vittorio Lumare ( http://airlab.ws.dei.polimi.it/index.php/LionHell_McMillan )
and it has been modified and improved in a Master Thesis work in Robotics and Artificial Intelligence by Alessandro Rosina (changing the name from "LionHell McMillan" to "LionHell McMillan II").
</p><p>Info about Thesis
</p>
<pre>TItle : LIONHELL MCMILLAN II: RIPROGETTAZIONE DI UN ROBOT ESAPODE BIOLOGICAMENTE ISPIRATO PER AREE MORFOLOGICAMENTE INSTABILI
Robot Name: LionHell McMillan II
Supervisor: Giuseppina Gini
Correlator: Vittorio Lumare
Author: Alessandro Rosina
Area: Robotics and Artifical Intelligence
Start date: 2014/09/10
End date: 2015/04/29
</pre>

<h2> <span class="mw-headline" id="state_art">State of the Art</span></h2>
<h3> <span class="mw-headline" id="Wheg">Wheg</span></h3>

The locomotion system is the key element that allows the robot to
interface and explore the surrounding environment and requires a careful choice
that meets the requirements of handling, mechanical simplicity and fluidity
motion, ensuring, in this case, the possibility to move easily
on rough terrain, overcoming obstacles of small and medium
size.

<h4> <span class="mw-headline" id="Definition_Wheg">Definition of the Wheg</span></h4>

[[File:Description wheg.PNG|300px]][[File:Wheg 0 rotazione.PNG|600px]]

The Wheg are a mechanism of locomotion for robots that combine
simplicity of movement of a wheel with the ability to scale and to overcome
obstacles arising from the use of the legs. The acronym derives
by the combination of words wheel and leg and mechanically it
consists of a central rotary axis and which are connected one or more bars
which perform the function of the legs.
The operation of a Wheg is extremely simple: the three legs are connected to a central axis that rotates
on itself and the point of contact with the ground is made from the end
of the leg.

<h4> <span class="mw-headline" id="_vs_Wheel">Wheg vs Wheel</span></h4>

The superiority of Wheg comparison to the use of a simple wheel is easily
demonstrated:

[[File:Ruota1ostacoloPiccolo.png|300px]][[File:Ruota2ostacoloPiccolo.png|300px]][[File:Ruota3ostacoloPiccolo.png|300px]]

<ol>
<li> Consider a wheel that is about to face an obstacle placed on the floor, much smaller than the radius
the wheel itself; </li>
<li> Once the wheel comes into contact with the obstacle, the clutch
that is generated will force the point of contact to remain in the same
position and while the torsion of the wheel will continue to act, the point
contact will function as a pivot. If the power of the engine will be
enough the result will be that the wheel will walk across continuing
in its path; </li>
</ol>
[[File:Ruota1ostacoloGrande.png|500px]]
<ol>
<li>Now consider a similar situation, in which, however, the obstacle that
wheel must be facing the same overall height of its radius (h similar to r). In this case the contact point is on the side of the obstacle,
and not above as in the previous case and the clutch that you should
come and create so that it can be climbed should be such that
allow the robot to move in a vertical manner with respect to the obstacle.
Typically, this situation is not a realistic scenario and the
experiment result will be that the wheel will start to slip on the spot,
continuously changing the point of contact with the obstacle. Due to the fact
the wheel would fail in this scenario, the wheel would fail for all
scenarios where h > r as the contact point will always be on the
side of the obstacle and not above. </li>
</ol>

[[File:Wheg1ostacoloGrande.png|300px]][[File:Wheg1ostacoloGrande.png|300px]][[File:Wheg1ostacoloGrande.png|300px]]

Consider now the previous example, in which h is similar to r, but where in place
of the wheel there is a Wheg three legs (in figures can be
observe the presence of a circle around the Wheg: this circle is purely
illustrative and serves only to relate the size of Wheg
compared to those of the wheel):
<ol>
<li>First, you can see the huge gap that the structure
presents, space that will be used to your advantage: the structure
is in fact able to exploit the empty space, facing the obstacle
from above and not from the side as in the case of the wheel; </li></i>
<li>The force exerted by the engines and the twist of Wheg will do the rest,
allowing the exploitation of the point of contact as a pivot to raise the Wheg frame and overcome the obstacle (you
always remember that the circle only serves to show the trajectory
of the three legs); </li>
</ol>

[[File:Wheg1ostacoloEnorme.png|400px]]

<ol>
<li>Now consider another example, in
where we have h > r, and in particular the case in which h = 3/2 r (as
there are 3 legs). In this extreme case the Wheg will not be
able to overcome the obstacle: the ability to climb it depends on how the
Wheg is capable of penetrating the profile of the obstacle. You can get
this goal by reducing the angle between the two upper legs, but this
undermine the structure of Wheg making unstable. </li>
</ol>

From this analysis it is possible to highlight the main advantages and disadvantages
of using a Wheg:
<ul>
<li> Pro: the ability to climb obstacles of greater height than those
addressed by a wheel having the same radius; </li>
<li> Pro: the speed of movement of the robot is still high; </li>
<li> Pro: the greater simplicity of construction and control compared to
a leg, which must necessarily be controlled by two or
three actuators; </li>
<li> Cons: The land on which it moves must be rough, in order to
do strength and be able to overcome the obstacle; </li>
<li> Cons: Legs too thin could sink surfaces
soft or non-rigid, such as sand or mud, due to the
reduced contact surface; </li>
<li> Cons: If your legs hit moving parts, such as long grass or cables
very thin, the Wheg could be twisted, latching
and risking damage to the robot in the case where the motors
trying to do too much force to break free. </li>
</ul>

<h2> <span class="mw-headline" id="CM_LionHell_II">Control and Mobility in LionHell II</span></h2>
<h3> <span class="mw-headline" id="Wheg_Lionhell_II">Wheg in LionHell II</span></h3>

[[File:Wheg LionHell.png|290px|right|Wheg of LionHell]]
[[File:Wheg LionHell II.png|300px|right|Wheg of LionHell II]]

The whegs are a mechanism of locomotion for robots that combine
simplicity of movement of a wheel with the ability to scale and to overcome obstacles arising from the use of the legs. The acronym derives
by the combination of words wheel and leg, and mechanically consist of a central rotary axis which are connected one or more bars
which perform the function of the legs. <br />
LionHell II has a total of 6 Wheg and each Wheg is composed of 3 bars arranged at 120° apart from each from the other, the ends of which is
mounted a foot slightly curved so as to ensure a secure grip on the ground. The movement of Wheg is simultaneous and each Wheg is controlled
by an independent motor that works in continuous mode, ensuring a smooth motion and robot suitable for every situation.
The Wheg that owns LionHell II is characterized by:
<ul>
<li> a structure baseline, aluminium, guarantees the point of contact with the central hub; </li>
<li> a basal structure of the foot, wood, molded according to an embodiment curve so as to adapt better to the ground and avoid jolts; </li>
<li> the foam, in contact with the foot structure, reduces shocks of the robot in contact with the ground; </li>
<li> rubber, in direct contact with the ground, protects the foam wear and allows the robot to move easily on any surface area; </li>
<li> the symbol allows to easily identify the components of the Wheg and position of the leg in the same robot; </li>
<li> the outline contour allows to understand intuitively the position with which the other members of Wheg be mounted. </li>
Compared to the previous model, we have kept the metal rod base and the rubber that was removed from the foot, since the movement of the same
LionHell would irreparably damaged the Wheg and in particular the delicate foothold.

<h3> <span class="mw-headline" id="Central_Passive_Joint">Central Passive Joint</span></h3>
This part will describe the role of the new central passive joint and the increase of the degrees of freedom that resulted.

<h4> <span class="mw-headline" id="DOF_LionHell_II">Degrees of Freedom of LionHell II</span></h4>
The number of degrees of freedom (DoF) of a material point is the number of independent variables needed to determine
uniquely its position in space (coordinates).
The degrees of freedom is a term used to define freedom of movement of a robot in the three spatial skills, and the
number of degrees of freedom of defining a robot configuration.
LionHell II is a hexapod robot equipped with Wheg, tail, a coupling motor that allows him to lift the front in order to better deal with
obstacles, and finally a central passive joint. In the figures you can
observe the degrees of freedom of LionHell II:
<ul>
<li> the movement of Wheg: each wheg has 1 degree of freedom, for a total of 6 degrees of freedom; </li>
<li> the movement of the joint motor and tail, each of which adds 1 degree of freedom, for a total of 2 degrees of freedom; </li>
<li> the central passive joint which was added later, and the green lines trace a possible movement of the front part of the robot. </li>
</ul>
The creation of a robot with a central joint in more passive arose from the idea to facilitate the movements when cornering and allow a more fluid
movement. In the next subsection we will explain in more detail the joint that has been added.

[[File:Dof wheg LionHell.PNG|300px|DoF of the whegs of LionHell II]][[File:Dof giunto LionHell.PNG|300px|DoF of the central passive joint of LionHell II]][[File:Dof testa coda LionHell.PNG|300px|DoF of the frontal part and of the tail of LionHell II]]

<h4> <span class="mw-headline" id="CPJ_LionHell_II">Central Passive Joint of LionHell II</span></h4>
LionHell II is equipped with a passive joint central, whose role is to accompany the movement of Wheg facilitating the movement when the
robot is going to bend. The passive coupling is constituted by:
<ul>
<li> a connecting member which allows rotation of a part of the body of LionHell II; </li>
<li> a pair of metal bars at the two ends of the connecting element, which are part of the security system; </li>
<li> two screws at the ends of the bars, their role is to define the angle of maximum rotation of the joint. </li>
</ul>
The screws may be replaced with shorter or longer, at difference if you want a rotation angle lower or higher. In
current state, the joint is able to rotate 10° to the right or to the left, while with the total absence of the screws the angle increases up to 30°. The addition
screw was necessary as it was presented the risk that the front whegs were to collide with intermediate whegs, risking to block the robot in tight corners.
The addition of the coupling passive was necessary because of the length of LionHell and the difficulty that this had in making some curves
narrow, and the basic idea was to simulate, in some respects, the hook present in the trailers and in trains, with the difference that in this case also
the trailer is able to bend, thus facilitating the movement.

[[File:Central passive joint high.jpg|200px|Central passive joint of LionHell II]][[File:Central passive joint scheme.PNG|200px|Scheme of the central passive joint of LionHell II]][[File:Central passive joint left.jpg|200px|Central passive joint of LionHell II]]

<h3> <span class="mw-headline" id="Tail">Tail</span></h3>

LionHell II is a mobile robot that has to face obstacles of small and medium size, and sometimes finds himself forced to having to overcome obstacles
large. In order for this operation to be successful, it is necessary that the robot does not fall backwards because of repeated setbacks caused from
the movement of the whegs seeking a foothold on which to do strength and lift the rest of the body of the robot.

[[File:Tail side LionHell.png|300px|Previous tail of LionHell]][[File:Tail high LionHell.png|280px|Previous tail of LionHell]]

The addition of the tail ensures greater stability during the climbs and allows him to lift the body preventing the possibility of falling back.
The morphological characteristics that allow the robot to move with greater ease, also facing major obstacles, are:
<ul>
<li> two motors in position mode, which allow the tail to bend and to force the tip when its intervention is required; </li>
<li> the total length of the queue, proportional to the length of the body; </li>
<li> the response of the tail which operates only when the robot is preparing to face major obstacles, recognizable by sensors head. </li>
</ul>

[[File:Tail side LionHell II.jpg |300px|Tail of LionHell II]][[File:Tail high LionHell II.jpg|300px|Tail of LionHell II]]

Compared to the original design, the tail has been modified to intensify the robot and increase the effectiveness and the force with which the tail presses on
terrain, namely:
<ul>
<li> the structure of the queue has been reinforced, in order to avoid that the new tail is damaged over time because of the force developed by engines
and the same weight of the robot; </li>
<li> the strength of the joint that allows the new queue was moving increased, using two motors in parallel that allow LionHell II to move with greater
ease while facing large obstacles. </li>
</ul>

<h2> <span class="mw-headline" id="RC_LionHell_II">Remote Control in LionHell II</span></h2>

<h3> <span class="mw-headline" id="Remote_controller">Remote controller</span></h3>

The figure shows the basic components of the remote control (excluding
a button and the switch, which for practical reasons are not shown in
figure, being incorporated into the external structure of the remote control).
The remote control is made up of:
<ul>
<li> a 9 V battery and 250 mAh which is the power; </li>
<li> an XBee Explorer Regulated that deals with the tension adjustment 3.3V, the signal conditioning and the basic activity indicators
and converts the signals from 5V to 3.3V in order to connect the system to any XBee module; </li>
<li> an XBee 4214A which plays the role of transmitting the signals received in input and communicates to the XBee installed on the body of LionHell II; </li>
<li> a three-axis analog accelerometer ADXL335, with card detection +/- 3g devoid of voltage regulator (the input voltage must be between 1.8V and 3.6V dc); </li>
<li> a circuit breaker switch that plays the role of power switch ON and OFF; </li>
<li> a red button unstable normally open, which allows the use the remote control while pressing. </li>
</ul>
The movement of LionHell II is via the inclination of the remote control(pointing the tip of the magician's hat forward and with the red button
upwards the robot is stationary, while raising or lowering the hat you can make it go forwards or backwards, and tilting
the remote control to the right or the left, the robot rotates to the right or left, respectively), which detects a change of axes X and Y by means
the accelerometer. The values are then passed to the XBee installed on remote control, which sends them directly to the XBee on LionHell II.

[[File:Remote controller 1.jpg|200px]][[File:Remote controller components.PNG|400px]]

<h3> <span class="mw-headline" id="XBee_LionHell">XBee of LionHell II</span></h3>

The goal of the XBee is to receive data from the remote control and send the data so
received to the control board LionHell II, with the result that the control board doesn't notice
even the existence of the XBee, as if it is reading data directly from the
remote controller.

The figures show the XBee 4214A used LionHell II, mounted directly
above the control board CM-510, at the center of the body of the robot,
and the the components underlying the XBee. How it is possible to
observe, are present (for each of the two digital inputs) a resistance
and a capacitor: the reason is easily explained.
The data transmitted from the XBee of the remote controller to the XBee of LionHell II are in analog form, but the inputs
control board does not require a digital type wave
square (obtainable via an inverting gate NOT, a Schmitt trigger,
a capacitor and a resistor) but through a filter of low-pass type (which
only requires the use of an RC circuit, based precisely on the use
of a resistor and a dynamic element, the capacitor).

[[File:XBee LionHell II.jpg|200px]]
[[File:XBee below LionHell II.jpg|300px]]

<h3> <span class="mw-headline" id="firmware_movement">Changes to the firmware</span></h3>

Once the signal is started by the remote, it's been installed on the XBee
on LionHell II and has been suitably modified to return
the original values read initially by the accelerometer of the remote control,
it is the turn of the control board CM-510.
The board acts as if it reads the values directly from the accelerometer,
doesn't even notice the existence of all the intermediate components, and
discriminates on the basis of these values the actions to be taken. Below there is
code of LionHell II reading the accelerometer values:

<pre>
// Read Remote Controller via XBee using Virtual Wires
{
resultX = adc_start( 4 );
resultY = adc_start( 3 );
bRemoteButton = (PINE & BTN_RIGHT) ;
// printf( "\r \n resultX resultY button: %u %u %d " ,resultX, resultY , bRemoteButton ) ;
// BUTTON
if ( bRemoteButton )
{
walking = true ;
}
else
{
walking = false ;
}
//X
if ( resultX > 340 )
{
turnL = 0 ; turnR=0; // Go Fwd
} else
if ( resultX < 300 )
{
turnL = 1 ; turnR=1; // Go Bwd
}
//Y
if ( resultY > 340 )
{
turnR = 1 ; turnL=0; // Turn Right
} else
if ( resultY < 300 )
{
turnL = 1 ; turnR=0; // Turn Left
}
}
</pre>

The code shows a first reading of the values X and Y of the accelerometer,
saved in variables resultX and resultY, later
is read the value of the red button by the variable bRemoteButton.
In the case where the red button is pressed then the variable walking
is set to true and based on the values of resultX and
resultY is chosen the direction to take.
The following code shows the behaviour of LionHell
II after the reception of the signals of the accelerometer and after that has been chosen
the action to be performed:

<pre>
//Walking Actions
if ( walking==1){
if ( turnL && turnR) {
int i ;
for ( i =0; i <3; i++){//Go Backward
dxl_write_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 1624 ) ;
dxl_write_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 600 ) ;
}
} else
if ( turnL ) {//Turn Left
int i ;
for ( i =0; i <3; i++){
dxl_write_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 1624 ) ;
dxl_write_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 1624 ) ;
// dxl_wri te_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 0 ) ;
}
} else
if ( turnR) {//Turn Right
int i ;
for ( i =0; i <3; i++){
dxl_write_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 600 ) ;
// dxl_wri te_word ( whegs_sx [ i ] ,
P_MOVING_SPEED_L, 0 ) ;
dxl_write_word ( whegs_dx [ i ] ,
P_MOVING_SPEED_L, 600 ) ;
}
} else
if ( ! ( turnL + turnR) ) {// If not turning
go_fwd ( ) ; // Restart walking
}
} else {// Stop Walking
stop ( ) ;
}
</pre>

In this case the choice of moving LionHell II is exclusively based on the
values of walking , turnL (turn left) and turnR (turn right).
In the case in which the values of turnL and turnR are both zero, then LionHell
II continue straight (the function sets the speed dxl_write_word
movement of each Wheg and its direction). In the other two cases,
however, with the modifying of the values of turnL and turnR, the robot will make the decision
to turn left or right by modifying the speed and
directions of the whegs.

<h2> <span class="mw-headline" id="Design_Lionhell_II">Design of LionHell II</span></h2>

<h3> <span class="mw-headline" id="Face_Lionhell_II">Face of LionHell II</span></h3>

LionHell literally means "lion hell", also translated as
Hellish Lion. Consequently, it was a must try and give it a feline aspect,
despite the bar sensory very long which is the head of the robot.
For this reason it was chosen as an example the Royal Bengal tiger
(Panthera tigris tigris), the tiger more widespread and more common, because we had practical problems in trying to create a real crest
around the head.
The new face is made from a plastic material, very lightweight, which allows
beautify LionHell II without increment excessively the weight,
while the colors were applied using permanent markers, leaving
sufficient space for the central sensor (and this is the reason of the mouth
arc).

[[File:Face LionHell.jpg|900px]]

File:Description wheg.PNG

2015-04-08T14:44:26Z

AlessandroRosina: The description of a wheg

The description of a wheg

File:Wheg 0 rotazione.PNG

2015-04-08T14:36:23Z

AlessandroRosina: The rotation of a wheg

The rotation of a wheg

File:Wheg1ostacoloEnorme.png

2015-04-08T14:35:28Z

AlessandroRosina: A wheg is trying to overcome an enormous obstacle

A wheg is trying to overcome an enormous obstacle

File:Wheg3ostacoloGrande.png

2015-04-08T14:34:42Z

AlessandroRosina: A wheg is trying to overcome a big obstacle (part 3)

A wheg is trying to overcome a big obstacle (part 3)

File:Wheg2ostacoloGrande.png

2015-04-08T14:34:09Z

AlessandroRosina: A wheg is trying to overcome a big obstacle (part 2)

A wheg is trying to overcome a big obstacle (part 2)

File:Wheg1ostacoloGrande.png

2015-04-08T14:33:48Z

AlessandroRosina: A wheg is trying to overcome a big obstacle (part 1)

A wheg is trying to overcome a big obstacle (part 1)

File:Ruota1ostacoloGrande.png

2015-04-08T14:33:15Z

AlessandroRosina: A wheel is trying to overcome a big obstacle

A wheel is trying to overcome a big obstacle

File:Ruota3ostacoloPiccolo.png

2015-04-08T14:32:50Z

AlessandroRosina: A wheel is trying to overcome a small obstacle (part 3)

A wheel is trying to overcome a small obstacle (part 3)

File:Ruota2ostacoloPiccolo.png

2015-04-08T14:32:30Z

AlessandroRosina: A wheel is trying to overcome a small obstacle (part 2)

A wheel is trying to overcome a small obstacle (part 2)

File:Ruota1ostacoloPiccolo.png

2015-04-08T14:32:03Z

AlessandroRosina: A wheel is trying to overcome a small obstacle (part 1)

A wheel is trying to overcome a small obstacle (part 1)

File:Power button 2.jpg

2015-04-08T14:25:44Z

AlessandroRosina: Power button of LionHell II

Power button of LionHell II

File:Power button 1.jpg

2015-04-08T13:57:37Z

AlessandroRosina: Power button of LionHell II

Power button of LionHell II

File:Shell 2.jpg

2015-04-08T13:43:15Z

AlessandroRosina: SHell of LionHell II

SHell of LionHell II

File:Shell 1.jpg

2015-04-08T13:39:51Z

AlessandroRosina: SHell of LionHell II

SHell of LionHell II

File:Remote controller 2.jpg

2015-04-08T13:33:43Z

AlessandroRosina: The remote controller of LionHell II

The remote controller of LionHell II

File:Face LionHell.jpg

2015-04-08T13:13:06Z

AlessandroRosina: Face of LionHell II

Face of LionHell II

File:XBee below LionHell II.jpg

2015-04-08T12:48:23Z

AlessandroRosina: Below the XBee on LionHell II

Below the XBee on LionHell II

File:XBee LionHell II.jpg

2015-04-08T12:44:17Z

AlessandroRosina: XBee on LionHell II

XBee on LionHell II

File:Remote controller components.PNG

2015-04-08T10:13:32Z

AlessandroRosina: Components of the remote controller of LionHell II

Components of the remote controller of LionHell II

File:Remote controller 1.jpg

2015-04-08T08:58:34Z

AlessandroRosina: Remote controller of LionHell II

Remote controller of LionHell II

User:AlessandroRosina

2015-04-07T16:03:22Z

AlessandroRosina:

<div style="clear:both"></div>

<div class="gumax-p-navigation-spacer"></div>


<div id="gumax-content-body">
<div class="gumax-firstHeading"></div>
<div class="visualClear"></div>


<div id="mw-content-text" lang="en" dir="ltr" class="mw-content-ltr"><table style="padding:10px" align="right" cellpadding="2" cellspacing="0" width="350px">

<tr>
<td colspan="2" style="text-align: center; background: #CCF; border-bottom: 1px solid #808080; border-left: 1px solid #808080; border-right: solid 1px #808080; border-top: 1px solid #808080;"><div style="font-size: 100%"><b>Alessandro Rosina</b></div>
</td></tr>
<tr>
<td colspan="2" style="text-align: center; background: lightgrey; border-bottom: 1px solid #808080; border-left: 1px solid #808080; border-right: solid 1px #808080;"> <div style="font-size: 100%"> [[File:Profilo.png|link:http://airlab.ws.dei.polimi.it/images/5/55/Profilo.png]]</div>
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> First Name:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> Alessandro
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> Last Name:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> Rosina
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> E-Mail:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> rosina.alessandro.0@gmail.com
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> Advisor:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> <ul><li>[http://airlab.ws.dei.polimi.it/index.php/User:GiuseppinaGini Giuseppina Gini]</li></ul>
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> Project page:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> LionHell McMillan II
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> Project page(s):
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> http://airlab.ws.dei.polimi.it/index.php/LionHell_McMillan_II
</td></tr>

<h2><span class="editsection"></span> <span class="mw-headline" id="Dati_Personali">Dati Personali</span></h2>
<p><b>Alessandro Rosina</b>
</p><p>nato a Domodossola il 01-02-1989
</p><p>e-mail: rosina.alessandro.0@gmail.com
</p><p><br />
</p>
<h2><span class="editsection"></span> <span class="mw-headline" id="Istruzione_e_formazione">Istruzione e formazione</span></h2>
<ul><li> <i>Settembre 2011</i> - Laurea in Ingegneria informatica (1° livello) votazione 88.
</li></ul>
<p><br />
</p>

<h2><span class="editsection"></span> <span class="mw-headline" id="Attivit.C3.A0_in_corso">Attività in corso</span></h2>
<h3><span class="editsection"></span> <span class="mw-headline" id="LionHell">LionHell McMillan II</span></h3>
<ul><li>Tesi II liv.
</li><li>Elaborato: LIONHELL MCMILLAN II: RIPROGETTAZIONE DI UN ROBOT ESAPODE BIOLOGICAMENTE ISPIRATO PER AREE MORFOLOGICAMENTE INSTABILI
</li><li>Url: http://airlab.ws.dei.polimi.it/index.php/LionHell_McMillan_II
</li><li>Relatore: Prof. Giuseppina Gini
</li><li>Correlatore: Ing. Vittorio Lumare
</li></ul>

User:AlessandroRosina

2015-04-07T16:02:47Z

AlessandroRosina:

<div style="clear:both"></div>

<div class="gumax-p-navigation-spacer"></div>


<div id="gumax-content-body">
<div class="gumax-firstHeading"></div>
<div class="visualClear"></div>


<div id="mw-content-text" lang="en" dir="ltr" class="mw-content-ltr"><table style="padding:10px" align="right" cellpadding="2" cellspacing="0" width="350px">

<tr>
<td colspan="2" style="text-align: center; background: #CCF; border-bottom: 1px solid #808080; border-left: 1px solid #808080; border-right: solid 1px #808080; border-top: 1px solid #808080;"><div style="font-size: 100%"><b>Alessandro Rosina</b></div>
</td></tr>
<tr>
<td colspan="2" style="text-align: center; background: lightgrey; border-bottom: 1px solid #808080; border-left: 1px solid #808080; border-right: solid 1px #808080;"> <div style="font-size: 100%"> [[File:Profilo.png|link:http://airlab.ws.dei.polimi.it/images/5/55/Profilo.png]]</div>
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> First Name:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> Alessandro
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> Last Name:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> Rosina
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> E-Mail:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> rosina.alessandro.0@gmail.com
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> Advisor:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> <ul><li>[http://airlab.ws.dei.polimi.it/index.php/User:GiuseppinaGini Giuseppina Gini]</li></ul>
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> Project page:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> LionHell McMillan II
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> Project page(s):
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> http://airlab.ws.dei.polimi.it/index.php/LionHell_McMillan_II
</td></tr>

<h2><span class="editsection"></span> <span class="mw-headline" id="Dati_Personali">Dati Personali</span></h2>
<p><b>Alessandro Rosina</b>
</p><p>nato a Domodossola il 01-02-1989
</p><p>e-mail: rosina.alessandro.0@gmail.com
</p><p><br />
</p>
<h2><span class="editsection"></span> <span class="mw-headline" id="Istruzione_e_formazione">Istruzione e formazione</span></h2>
<ul><li> <i>Settembre 2011</i> - Laurea in Ingegneria informatica (1° livello) votazione 88.
</li></ul>
<p><br />
</p>

<h2><span class="editsection"></span> <span class="mw-headline" id="Attivit.C3.A0_in_corso">Attività in corso</span></h2>
<h3><span class="editsection"></span> <span class="mw-headline" id="LionHell">LionHell McMillan II</span></h3>
<ul><li>Tesi II liv.
</li><li>Elaborato: LIONHELL MCMILLAN II: RIPROGETTAZIONE DI UN ROBOT ESAPODE BIOLOGICAMENTE ISPIRATO
PER AREE MORFOLOGICAMENTE INSTABILI
</li><li>Url: http://airlab.ws.dei.polimi.it/index.php/LionHell_McMillan_II
</li><li>Relatore: Prof. Giuseppina Gini
</li><li>Correlatore: Ing. Vittorio Lumare
</li></ul>

User:AlessandroRosina

2015-04-07T16:01:49Z

AlessandroRosina:

<div style="clear:both"></div>

<div class="gumax-p-navigation-spacer"></div>


<div id="gumax-content-body">
<div class="gumax-firstHeading"></div>
<div class="visualClear"></div>


<div id="mw-content-text" lang="en" dir="ltr" class="mw-content-ltr"><table style="padding:10px" align="right" cellpadding="2" cellspacing="0" width="350px">

<tr>
<td colspan="2" style="text-align: center; background: #CCF; border-bottom: 1px solid #808080; border-left: 1px solid #808080; border-right: solid 1px #808080; border-top: 1px solid #808080;"><div style="font-size: 100%"><b>Alessandro Rosina</b></div>
</td></tr>
<tr>
<td colspan="2" style="text-align: center; background: lightgrey; border-bottom: 1px solid #808080; border-left: 1px solid #808080; border-right: solid 1px #808080;"> <div style="font-size: 100%"> [[File:Profilo.png|link:http://airlab.ws.dei.polimi.it/images/5/55/Profilo.png]]</div>
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> First Name:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> Alessandro
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> Last Name:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> Rosina
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> E-Mail:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> rosina.alessandro.0@gmail.com
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> Advisor:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> <ul><li>[http://airlab.ws.dei.polimi.it/index.php/User:GiuseppinaGini Giuseppina Gini]</li></ul>
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> Project page:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> LionHell
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> Project page(s):
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> LionHell
</td></tr>

<h2><span class="editsection"></span> <span class="mw-headline" id="Dati_Personali">Dati Personali</span></h2>
<p><b>Alessandro Rosina</b>
</p><p>nato a Domodossola il 01-02-1989
</p><p>e-mail: rosina.alessandro.0@gmail.com
</p><p><br />
</p>
<h2><span class="editsection"></span> <span class="mw-headline" id="Istruzione_e_formazione">Istruzione e formazione</span></h2>
<ul><li> <i>Settembre 2011</i> - Laurea in Ingegneria informatica (1° livello) votazione 88.
</li></ul>
<p><br />
</p>

<h2><span class="editsection"></span> <span class="mw-headline" id="Attivit.C3.A0_in_corso">Attività in corso</span></h2>
<h3><span class="editsection"></span> <span class="mw-headline" id="LionHell">LionHell McMillan II</span></h3>
<ul><li>Tesi II liv.
</li><li>Elaborato: LIONHELL MCMILLAN II: RIPROGETTAZIONE DI UN ROBOT ESAPODE BIOLOGICAMENTE ISPIRATO
PER AREE MORFOLOGICAMENTE INSTABILI
</li><li>Url: http://airlab.ws.dei.polimi.it/index.php/LionHell_McMillan_II
</li><li>Relatore: Prof. Giuseppina Gini
</li><li>Correlatore: Ing. Vittorio Lumare
</li></ul>

User:AlessandroRosina

2015-04-07T16:01:15Z

AlessandroRosina:

<div style="clear:both"></div>

<div class="gumax-p-navigation-spacer"></div>


<div id="gumax-content-body">
<div class="gumax-firstHeading"></div>
<div class="visualClear"></div>


<div id="mw-content-text" lang="en" dir="ltr" class="mw-content-ltr"><table style="padding:10px" align="right" cellpadding="2" cellspacing="0" width="350px">

<tr>
<td colspan="2" style="text-align: center; background: #CCF; border-bottom: 1px solid #808080; border-left: 1px solid #808080; border-right: solid 1px #808080; border-top: 1px solid #808080;"><div style="font-size: 100%"><b>Alessandro Rosina</b></div>
</td></tr>
<tr>
<td colspan="2" style="text-align: center; background: lightgrey; border-bottom: 1px solid #808080; border-left: 1px solid #808080; border-right: solid 1px #808080;"> <div style="font-size: 100%"> [[File:Profilo.png|link:http://airlab.ws.dei.polimi.it/images/5/55/Profilo.png]]</div>
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> First Name:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> Alessandro
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> Last Name:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> Rosina
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> E-Mail:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> rosina.alessandro.0@gmail.com
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> Advisor:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> <ul><li>[http://airlab.ws.dei.polimi.it/index.php/User:GiuseppinaGini Giuseppina Gini]</li></ul>
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> Project page:
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> LionHell
</td></tr>
<tr>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; background-color: #EFEFEF;"> Project page(s):
</td>
<td style="vertical-align: middle; border-bottom:1px solid #808080; border-left:1px solid #808080; border-right: solid 1px #808080;"> LionHell
</td></tr>

<h2><span class="editsection"></span> <span class="mw-headline" id="Dati_Personali">Dati Personali</span></h2>
<p><b>Alessandro Rosina</b>
</p><p>nato a Domodossola il 01-02-1989
</p><p>e-mail: rosina.alessandro.0@gmail.com
</p><p><br />
</p>
<h2><span class="editsection"></span> <span class="mw-headline" id="Istruzione_e_formazione">Istruzione e formazione</span></h2>
<ul><li> <i>Settembre 2011</i> - Laurea in Ingegneria informatica (1° livello) votazione 88.
</li></ul>
<p><br />
</p>

<h2><span class="editsection"></span> <span class="mw-headline" id="Attivit.C3.A0_in_corso">Attività in corso</span></h2>
<h3><span class="editsection"></span> <span class="mw-headline" id="LionHell">LionHell</span></h3>
<ul><li>Tesi II liv.
</li><li>Elaborato: LIONHELL MCMILLAN II: RIPROGETTAZIONE DI UN ROBOT ESAPODE BIOLOGICAMENTE ISPIRATO
PER AREE MORFOLOGICAMENTE INSTABILI
</li><li>Url: http://airlab.ws.dei.polimi.it/index.php/LionHell_McMillan_II
</li><li>Relatore: Prof. Giuseppina Gini
</li><li>Correlatore: Ing. Vittorio Lumare
</li></ul>

LionHell McMillan II

2015-04-07T15:56:52Z

AlessandroRosina:

File:Tail side LionHell II.jpg

2015-04-07T15:38:05Z

AlessandroRosina: Tail (side) of LionHell McMillan II

Tail (side) of LionHell McMillan II

File:Tail side LionHell.png

2015-04-07T15:35:04Z

AlessandroRosina: Tail (side) of LionHell McMillan

Tail (side) of LionHell McMillan

File:Tail high LionHell II.jpg

2015-04-07T15:34:07Z

AlessandroRosina: Tail (from above) of LionHell McMillan II

Tail (from above) of LionHell McMillan II

File:Tail high LionHell.png

2015-04-07T15:25:56Z

AlessandroRosina: Tail (from above) of LionHell McMillan

Tail (from above) of LionHell McMillan

File:Central passive joint left.jpg

2015-04-07T14:55:35Z

AlessandroRosina: Central passive joint (from left) of LionHell McMillan II

Central passive joint (from left) of LionHell McMillan II

File:Central passive joint scheme.PNG

2015-04-07T14:52:24Z

AlessandroRosina: Central passive joint (scheme) of LionHell McMillan II

Central passive joint (scheme) of LionHell McMillan II

File:Central passive joint high.jpg

2015-04-07T14:00:03Z

AlessandroRosina: Central passive joint (from above) of LionHell McMillan II

Central passive joint (from above) of LionHell McMillan II

File:Dof wheg LionHell.PNG

2015-04-07T13:19:38Z

AlessandroRosina: DoF of the whegs of LionHell McMillan II

DoF of the whegs of LionHell McMillan II

File:Dof testa coda LionHell.PNG

2015-04-07T13:19:11Z

AlessandroRosina: DoF of the frontal part and of the tail of LionHell McMillan II

DoF of the frontal part and of the tail of LionHell McMillan II

File:Dof giunto LionHell.PNG

2015-04-07T13:17:34Z

AlessandroRosina: DoF of the central passive joint of LionHell McMillan II

DoF of the central passive joint of LionHell McMillan II

LionHell McMillan II

2015-04-07T12:21:14Z

AlessandroRosina:

File:Wheg LionHell II.png

2015-04-07T10:16:20Z

AlessandroRosina: Wheg LionHell McMillan II (hexapode robot of Alessandro Rosina)

Wheg LionHell McMillan II (hexapode robot of Alessandro Rosina)

File:Wheg LionHell.png

2015-04-07T10:09:36Z

AlessandroRosina: Wheg LionHell McMillan (hexapode robot of Vittorio Lumare)

Wheg LionHell McMillan (hexapode robot of Vittorio Lumare)