Wireless Communication for Mobile Robots

8/6/2019 Wireless Communication for Mobile Robots

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MR. G. KALAIARASSAN, M.E.LECTURER

MECHATRONICS ENGINEERINGKONGUENGINEERINGCOLLEGE

Wireless Communication for Mobilerobots


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Introduction to Robotics


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INDUSTRIAL ROBOTS


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INTRODUCTION TO MOBILE ROBOTS

Robotics has achieved its great success to date in the world of industrialmanufacturing bolted at its shoulder to specific position in the assembly linethe robot arm can move with a great speed accuracy to perform the respectivetask such as spot welding and painting

These commercial robot suffer for a fundamental disadvantages: lack of mobility .

A fixed manipulator has a limited range motion that depends on were its bolted down in the case of mobile robot would be able to travel throughout themanufacturing plant

Flexible applying its talents whenever its most effective


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Mobile Robots

An autonomous mobile robot knows at least some information about where itis and how to reach various goals and or way point along them.

A mobile robot needs locomotion mechanisms that enable it to move

unbounded throughout its environment.

Cooperation of mobile robots offers redundancy and flexibility.

Locomotion of mobile robots includes localization and navigation whichdemands knowledge of artificial intelligence, computer algorithm, controltheory and probability theory.


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Mathematics

Basic knowledge on following will help us to understandthe mobile robot control and coordination.Matrix

Vector algebraCalculusProbability theory

Computer programming


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HILARE ROBOT CAR LIKE MOBILE ROBOT


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Walking robot (semi automated)


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KITCHEN ROBOT TOUR GUIDE ROBOT


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FOOD TRANSPORT ROBOT SPY ROBOT


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MOBILE ROBOT SYSTEM

Environment Local Map

Knowledge,Data Base

Position Global Map CognitionPath

Planning

PathExecution

Acting

Real WorldEnvironment

MissionCommands

Motion

contro l

Actuator Commands

Path

LocalizationMap Building

Sensing

InformationExtraction andInterpretation

Percep tio

n

Raw Data

Decisionmaking

Determiningposition

Extractingdata


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CURRENT RESEARCH

Locomotion problem

Localization & Navigation

Computer vision


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LOCOMOTION (MOBILITY)

How can a mobile robot move unsupervised through the real worldenvironments to fulfill its task?

The first challenge is locomotion

How should a mobile robot moves and what is it about a particular locomotionmechanism that makes it superior to alternative locomotion mechanism?

To solve locomotion problem the mobile roboticist must understandmechanism and kinematics; dynamics and control theory


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ISSUES OF LOCOMOTION

Locomotion and manipulation thus share the same core issues of stability,contact characteristics, and environmental type.Stability- number and geometry of contact points- center of gravity

- static/dynamic stability- inclination of terrainCharacteristics of contact- contact point/path size and shape- angle of contact- frictionType of environment- structure- medium, (e.g. water, air, soft or hard ground)


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LOCOMOTION MECHANISMS USED IN BIOLOGICALSYSTEMS.


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LOCALIZATION

Localization is robot must determine its position in the environment.Challenges presents in localization is noise and aliasing.

Sensor Noise:

Sensors are the fundamental robot input for the process of perception,and therefore the degree to which sensors can discriminate the world state iscritical environment.

Sensor Aliasing:

Sensor aliasing is a phenomenon that humans rarely encounter. Thehuman sensory system, particularly the visual system, tends to receive uniqueinputs in each unique local state.


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CONTD

Leader less approach:

In leader less approach, where a specific robot is not assigned to conductthe robot swarms.

The motion of the group is carried based on interactions between individualgroup members (robot).

Here the chance of system failure is less when compared to leader follower

approach. If any robot from the group lacks the coordination with other robot means whole system will get collapsed.


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FLOCKING

Flocking is a form of collective behavior of large number of interacting agents with a common group objective.

Its emerged based on animal behaviors, biophysics and social sciences.Some flocking agents are,

Bees Fishes Birds Ants

PenguinsWhen we talk about flocking, a question may arise that what kind of the

problems we need to address on flocking.


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CONTD

For the computational viewpoint, there are a number of fundamental questionsthat have inspired this work:1. How do all robots work in distributed way?2. How do robots in flocks perform obstacle avoidance?

3. How do robots form into a desired formation and maintain it duringflocking?4. What is the minimum assumption that needs to make robots flock?5. What happens if some robots are crashed?

by referring the q.no.5, additionally two question arises,

1. How a robot knows other robots are correct or crashed?2.How the remaining correct robots effectively cooperate each other.


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FAULT TOLERANCE

Fault tolerant is ability of the system to overcome the failure to completethe assigned task

Collision avoidance

To keep robot together Finding the weakest failure Initially dead robot Crash permanent Byzantine failure

Transient failure Identifying alive among crashed robots


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Contd..

Some of the applications of mobile robot, Surveillance operations Satellites exploration Finding Nuclear pills in radioactive environment

Exploring hazardous environment In rescue operation before and after natural catastrophe Used in onshore oil refineries


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FUTURE RESEARCH DIRECTION

To avoid collision

To keep the robot together

To design a algorithm for finding the Initially dead robots, permanentlycrashed robots, transient failure robots, byzantine failure robots among theflocks of mobile robots. The above stated are weakest failure model in mobilerobots

Other failure model also avail, such as a robot can communicate with other butit cannot move, or a robot communicate facility is failed but still can move

To investigate the weakest system model


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Introduction to wireless communication inmobile robots

Communications and communication protocols play an important role inmobile robot.

The advent of high performance wireless local area network (WLAN) andad-hoc networking technology at relatively low cost, their use for wirelesscommunications among and control of mobile robots.

Multi robot system possess the capability of constructing network and performing cooperative work.

Key driving force in the development of cooperative mobile robotic systemis their potential for reducing the need for human presence in dangerousapplications.


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APPLICATION

Disposal of toxic waste

Nuclear power processing

Military or civilian search and rescue missions,

Planetary exploration

Security

Surveillance


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EVOLUTION OF ROBOT WIRELESS COMMUNICATION

Spread spectrumcommunication(ISM band) point-to-point link or

broadcast

Infraredcommunication

low data ratepoint-to-pointlink low cost

Spread spectrum,high data rate,long distance

multiple network structure


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Wireless communication technologies for mobile robots


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SYSTEM COMPOSING OF ROBOT


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COMMUNICATION STRUCTURE


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MESSAGES FROM A ROBOT TO CENTRAL STATION


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MESSAGES FROM CENTRAL STATION TO A ROBOT


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COMMUNICATION NETWORK

The robots are often equipped withlow-power

short-range wireless network interfaces

which only allow direct communication with near neighbours

WLAN- Network that needs some base towers

Ad-hoc- Network is an infrastructure less network where the

nodes themselves are responsible for routing the packets


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Cont..

Mobile nodes communicate with each other using multi hop

wireless links

There is no stationary infrastructure e.g., no base stations.

Each node in the network also acts as a router

Forwarding data packets for other nodes.

Topology in such a network can be

highly dynamic

traditional routing protocols can no longer be used


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Mobile Ad Hoc Networking (MANET)

MANET is the collection of mobile nodes which form atemporary network. The network has dynamic andunpredictable topology

Protocols can be broadly categorized intoProactive protocols

Reactive protocols


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Cont..

Proactive protocols(up to date routing information for each node)Destination-Sequenced Distance-Vector Routing protocol (DSDV)

Link-State Routing (LSR)

Reactive protocols(protocols create routes only when desired)On-Demand Distance Vector Routing (AODV)Dynamic source routing(DSR) (uses source routing rather than hop by hop)Labeled distance routing(LDR)

Feasible label routing (FLR)Sensors enabled events routing architecture (SEERA)


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Mobile robot networking layered model


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Parameters for single robot coordination

R i - The robot with rank number i, (i.e i is 1,2,3.n)

SCurPosObser - The set of position of robots at currentactivationSPrePosObser - The set of observed position of robots at

previous activation N act - The number of activation of some robot

D - Distance between the robotsScorrect - The set of position of correct robots


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MOBILE ROBOT SOFTWARES

WEBOTPLAYER/ STAGE/ GAZEBO

The most popular research robots areActive media roboticsK-Team SAI Robo

EBUG


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REFERENCES

Introduction to Autonomous Mobile Robots by Roland Siegwart and Illah R. Nourbakhsh ,A Bradford Book, The MIT Press, Cambridge, MassachusettsLondon, EnglandIntroduction to AI Robotics by Robin R. Murphy, A Bradford Book,

The MIT Press, Cambridge, Massachusetts, London, England


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THANK YOU

Wireless Communication for Mobile Robots

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