mobile robot report

8/2/2019 Mobile Robot Report

1/25

1 | P a g e

Mobile Robotics( Self Study Report )

By S.Ashwin Ram (EE07B090)Prof:Nitin Chandrachoodan


2/25

2 | P a g e

Introduction

This is my self study report on Mobile Robots, as a part of my final year B-tech project in Electrical

Engineering Department, IIT Madras under Professor Nitin Chandrachoodan. I am trying to build anew type of standalone terrestrial mobile robot, by borrowing some ideas from existing robots andsome new ideas of my own; to solve and tackle some interesting problems.

So this report briefly discusses about what mobile robots are, types of classification and theirapplication. However the main focus of this report will be on standalone terrestrial mobile robots;

highlighting key features, unique mechanisms (typically drive systems), working principle andapplications of these robots.

Finally there will be a description on what I have planned to build, its features, mechanisms andpossible applications of my fully functional mobile robot.


3/25

3 | P a g e

Table of contents1. Mobile robots.............................................................................................................04

1.1. Definition1.2. Mobile robot building blocks

1.3. Types of Classification1.4. Some major applications of mobile robots

2. Classification based on control and intelligence..........................................................062.1. Manual remote or tele-operated2.2. Gaureded tele-operated2.3. Line following robot2.4. Autonomously randomized robot2.5. Autonomously guided robot2.6. Sliding autonomy

3. Classification based on complexity and compute power.............................................073.1. Beam Robots

3.1.1. Mechanisms and principles3.1.2. Classification3.1.3. Applications

3.2. Swarm Robots3.2.1. Mechanisms and principles3.2.2. Classification3.2.3. Applications

3.3. Standalone Robots3.3.1. Mechanisms and principles3.3.2. Classification3.3.3. Applications

4. Examples of Standalone mobile robots.......................................................................134.1. GYROVER bot4.2. Tracked robots4.3. Stiction robot4.4. Amoeba bot4.5. STriDER bot4.6. Rotundus bot4.7. CIRCA bot4.8. MARS robot4.9. IMPASS robot

5. Final year Project: RC Ball...........................................................................................195.1. General Idea5.2. Implementation and hardware5.3. Working5.4. Advantages and applications5.5. Comlications and short comings of Ball based locomotion

Bibliography.....................................................................................................................25


4/25

4 | P a g e

1. Mobile robots1.1. Definition

Mobile robots are robots which have the ability to move around and interact with their environmentand not just hinged to a particular place. In contrast to industrial robots with jointed arm, gripperassembly, that is mounted to a rigid surface.

Mobile robots are focus of a great deal of research. There are many labs and research groups fromvarious universities and industries which are completely dedicated on researching mobile robots,because of their immense potential and varied application in industry, military, security, andentertainment.

In short any robot with the capability to navigate or move around comes under mobile robots.

1.2. Mobile robot building blocksDue to nature and function of mobile robots they set very particular system design constraints. Therobots should be capable of moving around efficiently and effectively. But at the same time theyshould integrate different elements into a self contained machine.

The key elements and parts of mobile robots are usually classified into: Mechanical frame Energy storage Actuators Embedded electronics Sensors

1.3. Types of Classification

There are many ways of classifying mobile robots; here we will be covering only some of the mostpopular classifications.

Mobile robots may be classified by:

Based on environment in which they navigate:

o Terrestrial robots: They travel on land. They can further be classified based onvarious terrains

o Aerial robots: They are robots with the ability to fly.o Aquatic robots: They are robots which travel on or under water

Based on control and intelligenceo Manual or Tele-operatedo Guarded Tele-operatedo Line followingo Autonomously randomized roboto Autonomously guided roboto Sliding autonomy

Based on complexity and compute power


5/25

5 | P a g e

o Beam robots ( most simple )o Swarm robots ( simple but large in number )o Standalone robots with special novel locomotion ( high compute power)

The first two type of classification is pretty straight forward from their names. We will later discuss a

little bit about the 2nd

and cover the 3rd

type a little bit in detail

1.4. Some major applications of Mobile robots

Bomb Disposal Exploration and collecting samples Surveillance / Reconnaissance Checkpoints / Inspections / Explosives Detection Route Clearance Explosive Hazard Identification Home application

Space exploration Defense and rescue robots

Inspection robots Agricultural robots

Autonomous Underwater Vehicles Autonomous lawn mower

Patrolling robotsIndustrial cleaner

Tourguide robots Entertainment robots


6/25

6 | P a g e

The above pics were taken from: http://moodle.epfl.ch/course/view.php?id=261

2. Classification based on control and intelligence

As mentioned above the following are the various types under this classification

2.1. Manual remote or tele-operated

A manually tele-operated robot is totally under control of a driver using a joystick or other controldevice. The device may be plugged directly into the robot, may be a wireless joystick, or may be anaccessory to a wireless computer or other controller. A tele-operated robot is typically used to keepthe operator out of danger.

2.2. Guarded tele-operated

A guarded tele-operated robot has the ability to sense and avoid obstacles which will override themanual control to prevent damage to robot or its surrounding environment. But will otherwise

navigate as driven similar to manual or tele-operated robot.

2.3. Line-following robot

it is one of the first type of Automated Guided Vehicles (AGVs). They typically follow a visual linepainted or embedded in the floor or ceiling or an electrical wire in the floor. Most of these robotsoperate on a simple "keep the line in the centre sensor" algorithm. They in general can t go aroundobstacles; they just have to stop and wait when something blocks their path.

2.4. Autonomously randomized robot

Autonomous robots are robots with random motion. They basically bounce off walls, they eithersense those walls with physical bumpers like or using electronic sensors like the Friendly Roboticslawn mower. The simple algorithm of bump and turn 30 degrees leads eventually to covers most orall of a floor.

2.5. Autonomously guided robot

An autonomously guided robot has some notion where it is and how to reach various locations.Using a variety of techniques "Localization" or knowledge of its current location is calculated; somemethods include using sensors such motor encoders, vision, Stereopsis (depth perception), lasers

and global positioning systems. Positioning systems often use triangulation and/or relative position


7/25

7 | P a g e

to determine the location and orientation of the robot, from which it can plan a path to its nextwaypoint or goal.

2.6. Sliding autonomy

more capable robots combine multiple levels of navigation under a system called sliding autonomy.Most autonomously guided robots, also offer a manual mode.

3. Classification based on complexity and compute power

3.1. Beam Robots

The word "beam" in BEAM robotics is an acronym for B iology, E lectronics, A esthetics, and M echanics . This term refers to a style of robotics that uses simple analogue circuits consisting of comparators, instead of a microprocessor in order to produce an unusually simple design (incontrast to traditional mobile robots) which compromises on flexibility for robustness and efficiencyin performing the task for which it was designed. There are exceptions to the convention of usingonly analog electronics and these are often referred to as "mutants". BEAM robots typically consistof a set of the aforementioned analog circuits which facilitate the robot's response to its workingenvironment.

The above pics were taken from http://www.flickr.com/photos/m27debord/224963811/#

3.1.1 Mechanisms and principles

In BEAM robotics the main focus is on building a robot which responds to a external stimulus. MarkW. Tilden developed the first circuit which simulated biological neuron behaviours. Tilden's circuit isoften compared to a shift register, but with several important features making it a useful circuit in amobile robot.

Other rules that are included (and to varying degrees applied):

1. Use the lowest number possible of electronic elements2. Recycle and reuse techno-scrap3. Use radiant energy (such as solar power)

There are a large number of BEAM robots designed to use solar power from small solar arrays topower a "Solar Engine" which creates autonomous robots capable of operating under a wide rangeof lighting conditions.


8/25

8 | P a g e

3.1.2. Classification

There are mainly two types of classification which is commonly used for classifying BEAM Robots

1. Types based on -trope

BEAM robots are classified on the basis of -trope , that is it is classified based on what theyreact to or to what stimulus they respond to. In general there is two type of response they caneither exhibit stay away or a seeking behaviour. Of the series, the phototropes are the mostpopular, as light-seeking robot would be the most beneficial behaviour for a solar-poweredrobot. Some common types

Audiotropes react to sound sources.

o Audiophiles go towards sound sources.o Audiophobes go away from sound sources.

Phototropes react to light sources.o Photophiles go toward light sources.o Photophobes go away from light sources.

Radiotropes react to radio frequency sources.o Radiophiles go toward RF sources.o Radiophobes go away from RF sources.

Thermotropes react to heat sources.o Thermophiles go toward heat sources.o Thermophobes go away from heat sources.

2. Types based on Movements

BEAM robots have a variety of movements and positioning mechanisms. These include:

Sitters : they are physically passive and exhibit no movements.o Beacons: Transmit a signal for other BEAMbots to use.o Pummers: Display a "light show".

Squirmers : Stationary robots that perform an interesting actiono Magbots: Utilize magnetic fields for their mode of animation.o Flagwavers: Move a display (or "flag") around at a certain frequency.o Heads: Pivot and follow some detectable phenomena, such as a light (These are

popular in the BEAM community. They can be stand-alone robots, but are moreoften incorporated into a larger robot.).

o Vibrators: Use a small pager motor with an off-centre weight to shakethemselves about.

Sliders : Robots that move by sliding body parts smoothly alo ng a surface while remainingin contact with it.

o Snakes: Move using a horizontal wave motion.o Earthworms: Move using a longitudinal wave motion.

Crawlers : Robots that move using tracks or by rolling the robot's body with some sort of appendage. The body of the robot is not dragged on the ground.

o Turbots: Roll their entire bodies using their arm(s) or flagella.


9/25

9 | P a g e

o Inchworms: Move part of their bodies ahead, while the rest of the chassis is onthe ground.

o Tracked robots: Use tracked wheels, like a tank. Jumpers : Robots which propel themselves off the ground as a means of locomotion.

o Vibrobots: Produce an irregular shaking motion moving themselves around a

surface.o Springbots: Move forward by bouncing in one particular direction.

Rollers : Robots that move by rolling all or part of their body.o Symets: Driven using a single motor with its shaft touching the ground, and

moves in different directions depending on which of several symmetric contactpoints around the shaft are touching the ground.

o Solarrollers: Solar-powered cars that use a single motor driving one or morewheels; often designed to complete a fairly short, straight and level course inthe shortest amount of time.

o Poppers: Use two motors with separate solar engines; rely on differentialsensors to achieve a goal.

o

Miniballs: Shift their centre of mass, causing their spherical bodies to roll. Walkers : Robots that move using legs with differential ground contact.o Motor Driven: Use motors to move their legs (typically 3 motors or less).o Muscle Wire Driven: Utilize Nitinol (nickel - titanium alloy) wires for their leg

actuators. Swimmers : Robots that move on or below the surface of a liquid (typically water).

o Boatbots: Operate on the surface of a liquid.o Subbots: Operate under the surface of a liquid.

Fliers : Robots that move through the air for sustained periods.o Helicopters: Use a powered rotor to provide both lift and propulsion.o Planes: Use fixed or flapping wings to generate lift.o

Blimps: Use a neutrally-buoyant balloon for lift. Climbers : Robot that moves up or down a vertical surface, usually on a track such as arope or wire.

3.1.3. Applications

The main practical application of BEAM robots has been very few

rapid prototyping of motion systems Hobby/education applications.

Limited commercial application, with some exceptions such as the iRobot, Roomba roboticvacuum cleaner and a few lawn-mowing robots.

3.2. Swarm Robots

Swarm robotics is a new approach to mobile robotics; they are simple and cheap robots with limitedsensing and computational capabilities but they are large in numbers. This approach is banked oncollective behaviour which emerges from the interactions between the robots and interactions of

robots with the environment.


10/25

10 | P a g e

Swarm robots are modelled after social insects such as ants and bees, where relatively simpleindividual rules can produce a large set of complex swarm behaviour.

The pic was taken from http://www.swarmrobot.org/


A key Principle in swarm robots is the communication between the members. The swarm behaviourinvolves constant change of individuals in cooperation with others, as well as the behaviour of thewhole group.

Other rules that are included (and to varying degrees applied):

1. They should be very simple with limited sensing capabilities2. Typically small size and low cost3. Team should consists of large number of robots

A swarm-intelligent approach to achieve meaningful behaviour at swarm-level is used instead of theindividual level . Swarm robots have high fault tolerance and parallelism due to large numbers


Swarm robots are mainly classified by the way the communicate

Direct CommunicationThis is the most straight forward way of intra-swarm and inter-robot communication. Thesend message directly to adjacent robots. The most common technologies for sending

messages from robot to robot in swarms are bluetooth, wireless LAN or infrared. Nowinfrared communication have advantage and disadvantage at the same time .Robots mustbe in direct line of sight. So why this is a disadvantage is clear, but how this can be anadvantage is realised when we look at natural swarms. In natural swarms we can very oftenfind that swarm-members only react to their direct environment. By using infraredtechnology, we can adopt this concept to the artificial swarm easily and the robots won'tpercept information that does not come from their direct environment.

Stigmergy:Here the exchange of information is done by changing the environment instead of directlycommunicating with the adjacent robots. The advantage of this type of message passing is

that the robots need not communicate to every single robot to pass on its message. A typical


11/25

11 | P a g e

example would be Ants and termites coordinate the building up of their nests by using thenests themselves to exchange information. For finding shortest paths at foraging or othertasks, ants don't tell every single of their mates where to go, but change the environment byplacing some pheromone on the way they chose. Following the most odorous path and

leaving their pheromone on this way again, the other ants cooperate and after a shortperiod, the shortest way stabilizes.

3.2.3. Applications

Potential applications for swarm robotics include tasks that demand for miniaturization orlarge number is required (nanorobotics, microbotics), like distributed sensing tasks in micromachinery or the human body.

And tasks that demand cheap designs, for instance mining tasks or agricultural foragingtasks.

Also some artists use swarm robotic techniques to realize new forms of interactive art.

3.3. Standalone Robots

Standalone robots as the name suggest they are single robots, which are completely self containedmobile robots. They are quite sophisticated with significant compute power. They can perform

complex tasks and more flexible than other types of robots. They can be either autonomous or

remotely controlled robot. They are generally designed for specific tasks and they are very robust inhandling and completing that task.


Standalone robots actually club a wide range of robots with mechanisms and principles completelydifferent from one another. So we can only discuss some general principles which are considered indesigning wheeled and legged robots. Similar principles are extended to other types aw well.

General Principles on wheeled robots

Static stability of a vehicle is guaranteed with 3 wheels Centre of gravity is within the triangle which is formed by the ground contact point

of the wheels. With 4 or more wheels dynamic stability is improved

However, they are hyper static and require a flexible suspension system. Bigger wheels allow to overcome higher obstacles

But they require higher torque or reductions gears. Combining actuation and steering on one wheel makes the design complex There is often an inverse correlation between controllability and manoeuvrability. In general, it is very difficult to come up with a drive configuration that simultaneously

maximizes stability, manoeuvrability and controllability.


12/25

12 | P a g e

General Principles on legged robots

Walking of a biped

not too far from rolling rolling of a polygon with side length equal to the length of the step the smaller the step gets, the more the polygon tends to a circle (wheel).

Mobile robots with legs (walking machines) The fewer the legs the more complicated the control of locomotion Stability, at least three legs are required for static stability For static walking at least 6 legs are required (in order to have a statically stable tripod of

legs in contact with the ground at all time) e.g., babies have to learn for quite a while until they are able to stand or even walk on their

two legs.

Holonomic/non-holonomic robots Controllable DOF: if a given robot has an actuator for every DOF of its task space, then all of

the DOF are controllable. Usually not all DOF are controllable, which makes robot controlharder.

For instance, a standard car has 3 DOF: posit ion (x,y) and orientation ( ). But only 2 DOF arecontrollable: driving through the gas pedal and the forward reverse gear, and steeringthrough the steering wheel. Since there are more DOF than are controllable, there aremotions that cannot be done, like moving sideways (that's why parallel parking is hard). Acar can get to any 2D position but it may have to follow a very complicated trajectory.

In robotics holonomicity refers to the relationship between the controllable and total DOF of

a given robot (or part thereof). If the controllable DOF is equal to the total degrees of freedom (in the task space) then the robot is said to be holonomic. If the controllabledegrees of freedom are less than the total DOF it is non-holonomic. A robot is considered tobe redundant if it has more controllable DOF than DOF in its task space.

Caution: omnidirectional != holonomic


13/25

13 | P a g e


Standalone robots are mainly classified based on their locomotion and drive system.

Legged robot: These robots have limbs (varied number) for locomotion similar to animals Wheeled robot: These robots use wheels (varied number) for locomotion, similar to vehicles Robot with Tracks: These robots use tracks for locomotion, similar to tanks Winged robots: These robots use wings for flying or swimming under water. They are further

classified aso Fixed wing: The wing is rigidly fixed, similar to airplaneo Free wing: The wing can generate force by flapping, similar to birds and insects

Propeller based robots: These robots use propellers or rotor for locomotion, similar tohelicopter

Miscellaneous: Since there are so many different drive systems, those which do not fit theabove categories come under this category

3.3.3. Applications

Standalone mobile robots are one of the most versatile type of mobile robots. Almost all applicationthat is listed under mobile robots can be listed under standalone mobile robot. So we need not listthem again here

4. Examples of Standalone mobile robotsSince my final year project is on designing a standalone mobile robot, we will focus on onlystandalone mobile robots by looking at some unique examples and try understand their working andmechanisms used

4.1. A Single-Wheel, Gyroscopically stabilized Robot (GYROVER)

"Gyrover" is a novel, single-wheel, gyroscopically stabilized robot. The Gyrover works based on theprinciple of gyroscopic precession; similar to the stability of a rolling wheel. Gyrover has an internalgyroscope aligned with the wheel and it spins along the direction of forward motion. The gyro's

angular momentum produces lateral stability when the wheel is stopped or moving slowly.

http://www.cs.cmu.edu/afs/cs/project/space/www/gyrover/gyrover.html


14/25

14 | P a g e

A tilt mechanism is used to tilt the gyro's axis about the fore/aft (roll) axis with respect to the wheel.Because the gyro acts as an inertial reference, the principal effect of the tilt action is to cause thewheel to lean left or right, which in turn causes the wheel to steer in the direction of leaning.Torques generated by a drive motor--reacting against the internal mechanism which hangs as apendulum from the wheel's axle--produce thrust for acceleration and braking.

Advantages and Applications

When resting on the ground, the tiltable flywheel can be used to right the vehicle. So therobot can recover from any orientation

The entire system is enclosed within the wheel to provide mechanical and environmentalprotection for equipment and mechanisms.

Gyrover can turn in place by simply leaning in the desired direction--with no special steeringmechanism-- enhancing manoeuvrability.

Full drive traction is available because all the weight is on the single drive wheel.

A large pneumatic tire may have very low ground-contact pressure, resulting in minimaldisturbance to the surface and minimum rolling resistance.

The tire may be suitable for travelling on soft soils, sand, snow or ice; riding over brush or othervegetation; or, with adequate b uoyancy, for travelling on water.

Potential applications for Gyrover are numerous. Because it can travel on both land and water, it canbe used as amphibian on beaches or swampy areas, for general transportation, exploration, rescueor recreation. Similarly, with appropriate tread, it should travel well over soft snow with goodtraction and minimal rolling resistance. As a surveillance robot, Gyrover could use its slim profile topass through doorways and narrow passages, and its ability to turn in place to manoeuvre in tightquarters. Another potential application is as a high-speed lunar vehicle, where the absence of

aerodynamic disturbances and low gravity would permit efficient, high-speed mobility.

4.2. Tracked robots

The pic is taken from http://www.robotshop.com/blog/sport-robots

There are many variants of track based drive system. The key feature of tracked robots is they havevery high traction. This particular tracked robot has two additional tracks in the front to help climb

raised platforms or steps. The tracked robots can manoeuvre over uneven surface effortlessly, as it


15/25

15 | P a g e

will always have some contact with ground and hence it hardly gets stuck. The robot is typically usedfor surveillance and bomb search robots

Working:

The two main tracks are the primary for locomotion and they are operated in the differential modeto turn the robot.

The two other tracks in the front can rotate 360 degree this helps the robot to get some kind of gripover the raised platform to climb it.

4.3. Stiction robot (static friction)

The pic is taken f rom http://www.youtube.com/watch?v=B5b77TkEQmg

Stiction robot is a very unique robot which uses static friction for moving. This is only a conceptrobot, it can move only in straight lines. But with little modification one can incorporate turning.From the picture one can see that the robot has mainly three parts. The central one is the part whichgenerates the required movement to enable locomotion the other two fronts and back part assistsin the motion.

Working

The robot moves forward by following a sequence of 3 steps. Each step: moving forward one part ata time. The system is based on cam shaft principles.

Step1: first, all the 3 parts are close together (the joints of links are all close to the centre of therobot). The left side cam shaft rotate outwards by 180 degree forcing the front part to move forward

Step2: Now the lift side cam shaft rotates back inwards by 180 degree, simultaneously the right sidecam shaft rotates outwards by 180 degree forcing the middle part to move forward towards thefront part

Step3: Now the right side cam shaft rotates inwards by 180 degree forcing the back part to come

closer to the middle part. This puts the robot back in the initial config. The 3 steps are repeatedsequentially to achieve locomotion.


16/25

16 | P a g e

4.4. Amoeba Bot totally propelled by its skin

The pic is taken f rom http://www.romela.org/main/Robots

The Amoeba Bot is a robot that has no legs or wheels. It is modelled after the single-celled amoeba;the robot uses nothing but its own skin to propel its body forward. It is shaped like a long tubeshaped donut type frame. The robots locomotion is obtained by using contracting and expandingactuator rings along the length of the robot. When these rings expand in its rear, and compact in itsfront, it produces a forward motion. This robot can be roughly classified as a tracked robot

Amoeba bot can be used effectively in search and rescue missions, since they can squeeze into thesmallest of spaces, including a fallen ceiling, or even a giant rock.

4.5. STriDER: Self-excited Tripedal Dynamic Experimental Robot


STriDER is a novel three-legged walking machine that exploits the concept of actuated passivedynamic locomotion to dynamically walk with high energy efficiency and minimal control. Unlikeother passive dynamic walking machines, this unique tripedal locomotion robot is inherently stablewith its tripod stance and it can change directions while walking
http://www.romela.org/main/File:STriDER_1and2.jpg


17/25

17 | P a g e

Operational Concept

The robot works on a principle very similar to pendulum. While performing a step, two legs act assupport legs while the other acts as a swing leg. The legs are placed such a way to push the centre of gravity outside of the support legs to initiate a step. As the body of the robot falls forward, the swing

leg naturally swings in between the two support legs and catches the fall. The body also rotates 180degrees to prevent the legs from tangling up. Once all three legs are in contact with the ground, therobot regains its stability . Gaits for changing directions are implemented by changing the sequenceof choice of the swing leg, the tripedal gait can move the robot in 60 interval directions for eachstep.

Advantages

The simple tripod configuration and tripedal gait of STriDER has many advantages over other leggedrobots; it has a simple kinematic structure; it is inherently stable (like a camera tripod); it is simple tocontrol as the motion is a simple falling in a predetermined direction and catching its fall; it is energyefficient, exploiting the actuated passive dynamic locomotion concept utilizing its built in dynamics;it is lightweight enabling it to be launched to difficult to access areas; and it is tall making it ideal fordeploying and positioning sensors at high position for surveillance, for example.

4.6. Rotundus bot

The Rotundus robot is a spherical bot that moves using an internal pendulum by shifting weights. Itis a sealed ball with no external moving parts all mechanisms are completely within the sphere. Fromoutside it looks deceptively like an ordinary ball

Working

There are two main principles to get a ball rolling on its own - to rotate a mass inside the ball or to

displace its centre of mass. In order to move, the pendulum is lifted in the desired direction, thecentre of mass gets displaced in front of contact point between the ball and the ground and the ballstarts rolling. Turning is accomplished by moving the pendulum to either side.

The pics are taken f rom http://www.rotundus.se/


18/25

18 | P a g e

4.7. CIRCA: Climbing Inspection Robot with Compressed Air

CIRCA (Climbing Inspection Robot with Compressed Air) is a climbing robot. It uses McKibben airmuscles to climb scaffolding structures. The robot uses 3 air muscles and is able to bend in anydesired direction by inflating (length reduces) or deflating (length increases) these air muscles. Byconnecting multiple CIRCA together in different shapes, you achieve different methods of locomotion. For example, actuating a doughnut robot would be useful for climbing a pole, and ahelical robot would be useful for transferring poles.


4.8. MARS: Multi Appendage Robotic System


The Multi Appendage Robotic System (MARS) is a six legged robot with its legs spaced axi-symmetrically around its body, allowing for omni-directional walking. Each limb uses a 2 DOFproximal joint, and a 1 DOF distal joint. This setup would allow MARS to cross over unstructuredterrain (terrain with variations in height). The system is fundamentally based on simplified biologicalneuron models.
http://www.romela.org/main/File:CIRCA3.jpghttp://www.romela.org/main/File:MARS.jpg


19/25

19 | P a g e

4.9. IMPASS: Intelligent Mobility Platform with Active Spoke System


IMPASS (Intelligent Mobility Platform with Active Spoke System) is a novel high mobility locomotion

platform for unmanned systems in unstructured environments. It uses rimless wheels withindividually actuated spokes, it can follow the contour of uneven surfaces like tracks and step over

large obstacles like legged vehicles while retaining the simplicity of wheels. Since it lacks thecomplexity of legs and has a large effective (wheel) diameter, this highly adaptive system can moveover extreme terrain with ease while maintaining respectable travel speeds, and thus has greatpotential for search-and-rescue missions, scientific exploration, and anti-terror responseapplications.

5. Final year Project: RC Ball

After looking up various standalone mobile robots and their mechanisms. I decided to design aRemote controlled ball with capabilities of Omni-directional movement and a surveillance camera.

5.1. General Idea :

The following diagram gives a brief layout of the system
http://www.romela.org/main/File:IMPASS.jpg


20/25

20 | P a g e

5.2. Implementation and Hardware:

Remote Control

The remote control will be realised using PS2 wireless serial joystick. The signals from the joystickwill be transmitted wirelessly and the receiver will be interfaced with a microcontroller.

Joystick

The pic is taken from http://www.jbhifionline.com.au/game/ps2/

Remote Platform (Ball)

The remote platform is essentially the ball with the drive system and camera. The drive system will

be housed within the ball and the camera will be magnetically suspended outside the ball. It willhave the RF receiver to receive signals from the joystick and a micro-controller to interpret thesignals and control the drive system accordingly. The camera will be linked to Bluetooth transmitterto transmit the live video feed to a smartphone.


21/25

21 | P a g e

Drive System

The drive system is omnidirectional, implemented using four transwheels placed on four sides of asquare. The wheels shall be inclined in such a way that it will make perpendicular contact with the

inner surface of the ball. Each of these wheels will be powered by DC motor.

Transwheels

The pic is taken f rom http://www.kornylak.com/wheels/transwheel.html

Drive system schematic:


22/25

22 | P a g e

Camera

A small spy-cam with Bluetooth transmitter will be magnetically suspended outside the ball. Themechanism will be such the camera will be in the same horizontal level even when the ball ismoving. Another possibility is to house the Camera inside the ball itself if the ball is chosen to be

transparent.

Camera

The pic is taken f rom http://www.spycamera.org.uk

Smart phone

A smart phone with Bluetooth capabilities can be used to receive the transmitted live video stream,to be displayed on its screen. A small application should be developed for the smart phone to enablethis capability. The smart phone can be attached to the joystick to be viewed by the controller.


23/25

23 | P a g e

5.3. Working

The working of the RC Ball is based on the principle of shifting centre of gravity. The robot isdesigned in such a way that majority of the contribution to the position of centre of gravity of therobot comes from the drive system. Therefore as the drive system inside the ball moves, it causes a

shift in centre of gravity causing the ball to roll. Since the drive system is omnidirectional, the ballcan roll in any desired direction.

5.4. Advantages an d Applications The shape of the robot ( spherical ) makes it natural for omnidirectional movement It is impossible to knock the robot out of its orientation (to render it unmovable by flipping

etc.) The robot will be able to manoeuvre through most of the terrains because it is based on

rolling The robot will be very robust, and will require very less maintenance as it is sealed and will

have a smooth exterior (no external moving parts) With little modification(buoyancy, water tight seal and retractable fins) the robot can be

made capable of even moving on the surface of water The shape of the robot is ideal for using it in pipeline and cave exploration. The robot can be made extremely noiseless as all the moving parts will be concealed within

the sphere All the features above make it a good candidate for surveillance. It can also be used as a toy for kids, to wrestle each other of the table or race each other etc.


24/25

24 | P a g e

5.5. Complications and short comings of Ball based locomotion The inclination it can climb is limited to the centre of gravity of the ball It has almost zero static friction with hard surfaces so it cannot anchor itself to these

surfaces

Especially on an inclined plane it will be a challenging task to make it stand still The acceleration of the robot is limited by gravity. Recharging the device may not be very straight forward, must look for methods like wireless

charging (induction). Achieving halting stops might be difficult.


25/25

Bibliographyhttp://science.howstuffworks.com/robot3.htm http://www.rotundus.se/ http://en.wikipedia.org http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=332 http://www.irobot.com/gi/ground/510_PackBot http://www.engadget.com/2004/06/25/irobots-tactical-mobile-robot-the-packbot http://www.wordiq.com/definition/Image:Sbot_mobile_robot_passing_gap.jpeg http://www.youtube.com http://www.swarmrobot.org/tiki-index.php http://www.romela.org/main/Robots http://www.ri.cmu.edu http://moodle.epfl.ch/course/view.php?id=261
http://science.howstuffworks.com/robot3.htmhttp://science.howstuffworks.com/robot3.htmhttp://www.rotundus.se/http://www.rotundus.se/http://en.wikipedia.org/http://en.wikipedia.org/http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=332http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=332http://www.irobot.com/gi/ground/510_PackBothttp://www.irobot.com/gi/ground/510_PackBothttp://www.engadget.com/2004/06/25/irobots-tactical-mobile-robot-the-packbothttp://www.engadget.com/2004/06/25/irobots-tactical-mobile-robot-the-packbothttp://www.wordiq.com/definition/Image:Sbot_mobile_robot_passing_gap.jpeghttp://www.wordiq.com/definition/Image:Sbot_mobile_robot_passing_gap.jpeghttp://www.youtube.com/http://www.youtube.com/http://www.swarmrobot.org/tiki-index.phphttp://www.swarmrobot.org/tiki-index.phphttp://www.romela.org/main/Robotshttp://www.romela.org/main/Robotshttp://www.ri.cmu.edu/http://www.ri.cmu.edu/http://moodle.epfl.ch/course/view.php?id=261http://moodle.epfl.ch/course/view.php?id=261http://moodle.epfl.ch/course/view.php?id=261http://www.ri.cmu.edu/http://www.romela.org/main/Robotshttp://www.swarmrobot.org/tiki-index.phphttp://www.youtube.com/http://www.wordiq.com/definition/Image:Sbot_mobile_robot_passing_gap.jpeghttp://www.engadget.com/2004/06/25/irobots-tactical-mobile-robot-the-packbothttp://www.irobot.com/gi/ground/510_PackBothttp://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=332http://en.wikipedia.org/http://www.rotundus.se/http://science.howstuffworks.com/robot3.htm

mobile robot report

Documents