Robotic Sensor Network: Wireless Sensor Platform for Autonomous

Topology Formation Project: 04043

Sponsored By:

Advisor: Dr. S. Jay Yang, CE Manager: Steven Boughton, ME

Brian Teaney, CE Ryan Johnson, EE

Jack Tsai, EE Matt Hrivnak, IE

Gregory Rosenblatt, ME Shannon Buckland, ME

Presentation Overview

• Project Overview

Problem Statement, Design Process, Project Constraints

• Prototype Design Design Overview, Testing and Problems Encountered

• Final DesignMechanical and Electrical Redesign, Software Development, Final Testing

• Future Plans• Questions

Problem Statement

To develop a group of sensor platforms that can communicate with one another wirelessly and move from original deployment locations to form a desired network topology that offers full, energy efficient, and robust coverage. The platforms will be relatively small and lightweight. They must be able to work as a group to maximize the sensor networks life span. The end result of this project is to have a functioning group of no less then three sensor platforms that can be used as a test platform for future research and expandability.

Design Process (Phase I – Winter 2003)

1 2 3

LocomotionShannon

Greg

SensingJackMatt

CommunicationsBrianRyan

ProjectManager /

Project Advisor

LocomotionShannon

Greg

SensingJackMatt

CommunicationsBrianRyan

4InitialConcepts

FinalRecommendations

HardwareShannon

JackMatt

SoftwareBrianRyanGreg

Objectives andSpecifications

HardwareShannon

JackMatt

SoftwareBrianRyanGreg

Mechanical

Electrical

Movement

Sensing

Communications

5

Topology

FinalPrototype

Design

1

2

3

Needs Assessment

Concept Development

Feasibility Assessment

Objectives and Specifications4

5 Analysis and Design

Phase IISpring2004

Design Process

(Phase II – Spring 2004)

6 8

ElectricalRyanJack

MechanicalShannon

9

FinalDesign

6

7

8Initial Testing

Problem Assessment

Redesign

Final Testing9

ElectronicsRyanJack

MovementBrian

ShannonGreg

PICBrian

Problems 7

ElectronicsRyanJack

MovementBrian

ShannonGreg

PICBrian

Recommendations

HardwareShannon

JackMatt

SoftwareBrianRyanGreg

Mechanical

Electrical

Movement

Sensing

Communications

TopologyTopology

Formation

Phase IIIFall2004

Project Constraints

• Budget– Original funding fell through– Final budget not approved until March 19

• Timeline– Accelerated design time: steep learning curve– 2 phases: Prototype and Final Design

• Limited Lab Equipment and Software– Limited shop time– PIC programmer– Design Software

Prototype Design Overview

• 3 Tier Layout– Weight distribution– Location advantages– Ease of assembly– Ease of redesign

• Locomotion Tier A– Motors, tires, power

• Sensor Tier B– IR sensors

• Communications Tier C– Prototype board

A

B

C

Prototype Design Specifications• MICA2DOT

– Run on an Atmel ATmega128L running at 4MHz, w/ 128k of program memory.

– Handles the communications and network topology.

• Sharp GP2Y0A02YK IR Sensor– Less influence on the color

of reflected objects, reflectivity

– Current required: 33mA – Analog voltage

corresponding to distance

• PIC18F458 model– Up to 40MHz clock. 8k of

program memory.– Will monitor the infrared

sensors and control the locomotion of the robot.

• Motors– Bipolar Stepper Motor– 12 VDC @ .6 A

Prototype Testing and Problems Encountered

• Turning Capability– Units could not execute turns– Solved by widening the base to 5” by 9”

• Programming the PIC– Initial PIC selection did not match programmer compatibility– Solved by selecting different PIC micro controller (PIC18F458)

• Motor Control / Power– Supply currents insufficient to drive original motors– Selection of new motors and addition of higher rated

regulators– Bipolar Stepper Motor (1.8o step, 2.72VDC @ .4A, 650 g-cm)

• Overheating– Units were prone to overheating in a matter of seconds– Solved by adding heat dissipation elements to final design

Final Design Redesign

• Mechanical Redesign– Aspect Ratio (2:1)– Tire Coupling– Sensor Mounts (4 vs. 8)– Material

• Electrical Redesign– Board Size– Voltage Regulation– Heat Sink– Battery

Final Design Software Development

The final software development issue involved integration of the three main components that had been programmed separately.• Motors/Sensors• Communications• Topology Formation Algorithm

Final Design Software Integration

Topology algorithm interfaces with other components

• Integration with Motors/Sensors– Topology interface calls directly-related

functions• Integration with Communications

– Intermediate code created to link the Topology interface with proper calls to send and received messages

PIC Programming Issues…

Final Testing

• Hardware Testing– Movement– Errors in Turning

• Software Testing– Communications Verification

• PIC Testing– Unsolved Problems

Back and Forth Movement Error

0

0.5

1

1.5

2

2.5

3

3.5

1 2 3 4 5

Iteration

Dis

pla

cem

ent

(cm

)

15 cm 50 cm 100 cm

Repeated Turn Error

0

1

2

3

4

5

6

7

1 2 3 4 5

Iteration

Dis

pla

cem

ent

(cm

)

3 RPM 30 RPM 36 RPM

Future Work

• Reliable, user friendly, and upgradeable sensor platform– Programmable via wireless communication– Easy to maintain and upgrade

• Scalable and robust topology formation– Distributed control leads to fast convergence– Adaptive to sensor failure or energy

exhaustion

• Application driven topology adaptation– Mission critical sensor network – Formation adapts to application needs