RoboTeamRoboTeam

05/04/201205/04/2012

Submitted by:Submitted by: Costia Parfeniev, Boris PinzurCostia Parfeniev, Boris Pinzur

Supervised by: Supervised by: Kobi KohaiKobi Kohai

AgendaProject GoalsDesignZigbee™ ExplainedArchitectureModules BreakdownEncountered Difficulties Suggestions for improvements

Project goalsDevelop a wireless communication infrastructure

among several robots for future projects.

The project shall provide a simple software API for

future reuse.

The design shall allow using more than 2 robots by

revising the application.

Create an autonomous system of two robots.

Demonstrate the ability to coordinate movement and

activity using the Zigbee™ wireless comm.

DesignUsing a standard 2 level robot base.

Which includes: Chassis

2 Servo motors

Wheel encoders

MSP430 as the main application processor.

EZ430-RF2480 board as the communication module.

A rotating sensors turret with: 2 IR distance sensors.

IR LED Array beacon.

IR photodiode.

Zigbee ™ ExplainedThe Zigbee protocol is a low-power, low-resource

devices, with an easy to use API.

Supports several network topologies

Zigbee network consists of a coordinator and

several routers or end devices

Black: Coordinator

Red: Router

White: End Device

Zigbee ™ HWPC Interface:

End Device

Power

Data

Physical structureZigbee board EZ430-

RF2480

CC2480

MSP430F227

4

MSP430 BoardMSP-TS430PZ100

MSP430FG4618

MobilityLeft

ServoRight Servo

Right Encod

er

Left Encod

er

SensorsTurret Servo

Forward IR

Distance Sensor

Back-Facing IR Distance Sensor

Close range DiscoveryIR Beacon

Forward IR

Photodiode

Upper Power Supply

(5V,3.3V)

Lower Power Supply (5V)

Robot Images

Software/Logical structure

ApplicationRemote

Communication module

Local Wireless Network

Sensors

Motors

Close-range communication and discovery

The module is based on the EZ430-RF2480 board, controlled the main MSP430FG4618 µC

Remote Communication:

EZ430-RF2480

CC2480MSP430F2274

MSP430 BoardMSP-

TS430PZ100MSP43

0FG4618

RF Antenna

SPIUART

Close range discovery system

IR receiver

IR Beacon

Purpose: Identifying near-by robots.Hardware:Beacon array - IR LED IR photodiode IR Distance sensor

Servo

IR Range Sensor

MotorsPurpose: Mobility and control infrastructure.Hardware:

2 servo motors2 encoders

ApplicationThe application works in several stages:

Initialization and calibrationTurn on all HW modules and calibrate the servos.

DiscoveryUse of IR sensor, beacon and distance sensor to find adjacent robots (Zigbee is used to announce any discovery to the network).

AlignmentUse IR distance sensors to get the robots closer and align them.

MovementThe robots use IR distance sensor to periodically correct distance and alignment errors, and transmit the sensor’s results to each other.

Encountered Difficulties Received IR signal shape is dependent at varying distances.

Received data from the IR requires error detection.

Calibration – different timings, speed and angles for the servos.

Some of the parts are of different models on each robot.

Timing jitter due to ADC sampling and long interrupt handlers.

Zigbee operation and integration.

IR LED narrow angle.

Not enough timers on the chip.

Suggestions for improvementsOS like infrastructure – reduce real-time tasks using threads.

Generalized local coordinate system (turret, body, encoder

wheel).

Fully autonomous calibration.

Power consumption analysis and reduction.

Data transmission over IR.

Simulator for application testing before trying it on HW.

Complex distributed applications.

Movement Coordination Demo Video

http://www.youtube.com/watch?v=6vLCBT9K84c

Thank you !