Collaborative mobile Collaborative mobile robotsrobots

Rory McGrath05000874

Progress ReportProgress Report

IndexIndexIndroductionTechnology BackgroundSystem Design And OperationProgress To Date/Remaining Work

IntroductionIntroduction

This project is concerned with the design and construction

of a battery powered robot swarm and the development of

an application to illustrate the practical use of a

collaborative robot swarm.

OverviewOverviewBuild a small swarm of robotsControl a robot over a wireless

PC based GUIAddition of collision detectionPorting of a control application to

a mobile handset Develop software to illustrate

collaborative tasks.

Milestones (1)Milestones (1)Construction of an operational

robot. Movement is to be controlled over a wireless interface from a PC based application

Addition of collision detection sensor on the robot. Porting of control application to a mobile handset

Milestones (2)Milestones (2)Construction of multiple robots

and integration of functionality to support a “locating” capability in the swarm.

Demonstration of collaborative movement of the robot swarm.

Development of an application to illustrate the practical use of a collaborative robot swarm

Technology BackgroundTechnology Background

Duty CyclePulse-Width Modulation (PWM)Opto-isolatorsGumstix

Duty CycleDuty Cycle

The term “Duty Cycle” is used to describe the time that a system is in its “active” state. The proportion of time during which a system is operated is defined as its “Duty Cycle”.

Pulse-Width Modulation Pulse-Width Modulation (PWM)(PWM)The pulse width modulation (PWM)

of a signal involves the modulation of its duty cycle.

A square wave is used.The pulse width of the square wave is

modulated resulting in the variation of the average of the waveform.

Opto-isolatorsOpto-isolators

Opto-isolators are made up of a light emitting device and a light sensitive device. The two devices are not connected by any wire or electrical means. The only connection is a beam of light

GumstixGumstixThe micro-processor

being usedSpeed of 400MHz -

(Intel Xscale PXA255)16MB flash memory Bluetooth wireless

connectivity64MB of RAM

System Design & System Design & OperationOperation

The robot is designed on the basic Scooterbot robot

platform. Gumstix is the micro-processor used to

control the robot operation and to provide the inter-

robot communications.

HardwareHardware

MotorsGumstix

MotorsMotorsEach robot has two motors.Two 5 volts motors are used. 5 volts are placed on the motors red wire with 0

volts on the black wire and a 3-5 volt pulse on the white wire with a width of 0.75 to 2.25ms and a period of 18ms.

GumstixGumstixThe Gumstix generates the PWM signal used to

power the motors.The outputs for the PWM of the Gumstix are the General Purpose Input Output (GPIO) pins 16 and 17.

These are set to output the PWM signal rather than operate as GPIO.

GumstixGumstix

It was found that the Gumstix outputs a PWM signal of a maximum 3V.

More than 3 volts is required for the 4N25 chip in the opto-Isolator circuit to activate.

To compensate for this an extra power supply (5V), a 2N3904 transistor and a 100kOhm resistor are needed to successfully power the motors.

Python PWM InitializationPython PWM InitializationThe 2 GPIO pins required for PWM are initialized for

PWM output through a python script.The PWM functions are controlled by 3 registers. The 3 registers are PWM_CTRL, PWM_DUTY and

PWM_PERVAL.

Python BluetoothPython BluetoothBluetooth is the inter-robot communications medium. It will allow the lead robot (server) to communicate

with the other robots (clients).

Python ServerPython Server

import bluetoothserver_sock=bluetooth.BluetoothSocket( bluetooth.RFCOMM )port = 1server_sock.bind(("",port))server_sock.listen(1)client_sock,address = server_sock.accept()print "Accepted connection from ",addressdata = client_sock.recv(1024)print("Data Recieved... %s"%data)client_sock.close()server_sock.close()

Python ClientPython Client

import bluetooth

bd_addr = "00:80:37:2E:46:37"

port = 2

sock=bluetooth.BluetoothSocket( bluetooth.RFCOMM )sock.connect((bd_addr, port))

sock.send("Hello World")

sock.close()

J2MEJ2ME

J2ME is a java platform designed for mobile phones. J2ME can be viewed as a subsection or

subset of the complete J2SE while still containing some extra features.

For this project J2ME is the language used to allow communication between the phone and

Gumstix. The Java program connects to the Gumstix through the Bluetooth device in phone.

Work done (1)Work done (1)An Opto-isolator circuit has been successfully built and tested using the Signal Generator.The PWM pins have been successfully initialized via a python script.Values where hardcoded to the PWM pins and successfully outputted to the oscilloscope.A python script was written which successfully outputted “forward” motion PWM signals to the oscilloscope.The Gumstix was connected to the motor via the Opto-isolator and it was found that an extra voltage was needed to activate the 4N25 chip

Work Done (2)Work Done (2)Changes were made to the Opto-isolator to allow for the Gumstix to successfully run the motors.A J2ME client was created for a mobile phone.A J2ME GUI was created for the client.Changes were made to Gumstix folders to allow for a successful Bluetooth connection with a laptop.A Gumstix Server was written and the Client for a PC and mobile phone were successfully tested.

Remaining WorkRemaining WorkThe construction of multiple robots has still to be carried outThe locating capability of individual robots in swarm is required.The swarm must demonstration collaborative movement.(movement in formation & Orderly dispersion)Illustration of the use of collaborative movement has yet to be shown.

SummerySummery

This project is concerned with the design and construction

of a battery powered robot swarm and the development of

an application to illustrate the practical use of a

collaborative robot swarm.

A simple Robot has been constructed. Bluetooth

communication has be achieved. Locating capability of

individual robots in swarm and Illustration of the use of

collaborative movement remains to be achieved.

Questions?Questions?