PT 5000

Pooja Rao

Ted Tomporowski

December 7, 2004

Functional Overview

To create an autonomous vehicle that is capable of:

Following a reflective tape path from start to finish Stopping at specifically marked checkpoints and waiting for user

recognition to continue Display of number of checkpoints reached Diverting from the path to avoid obstacles

Specifications

Will follow reflective tape path when unobstructed.

Will detect obstacles within 2’, and divert from the path in an optimal manner to avoid them

Will stop at designated checkpoints Lightweight Will not be affected by ambient light Minimum runtime of 10 minutes

Restrictions

Maximum number of checkpoints: 3 Obstacle minimum size: 8” wide x 12” long x 2” high Path cannot turn more sharply than the turning radius

of the car Obstacles cannot be placed such that they are very

close to the track but not on it Checkpoints cannot be obstructed, and must be on

straight portions of the track

Components

Servo Motor DC Motor Sharp GP2D12: distance-measuring sensor Fairchild QRB1134: phototransistor reflective

object sensor HCS12

Steering

The vehicle will have front wheel steering, controlled by a servo motor.

DC Motor

PWM ports on the HCS12 in conjunction with H-Bridges will be used to control the DC motor and the speed of the vehicle.

A higher voltage will be supplied to the motor when the vehicle is turning to counteract the effects of added friction, thus maintaining the vehicle’s speed.

GP2D12 – IR Analog Distance Sensor

The Sharp GP2D12 is a general-purpose type distance-measuring sensor, which consists of a position sensitive detector and an infrared emitting diode and

signal processing circuit This sensor has a 2” beam

width

Distance Sensor Output

QRB1134 – Opto-reflector

The QRB1134 consists of an infrared emitting diode and an NPN silicon phototransistor. The phototransistor responds to radiation from the emitting diode only when a reflective object passes within its field of view.

Datasheet optimum range

4 millimeters

Port Diagram

Design & User Interface

Two buttons are present– Start Button: this button is

toggled to either start the vehicle initially, or to tell it to continue when it is halted at a checkpoint

– Reset Button: this button is used to reset the vehicle to its start state

Two sets of LED’s are present– The blue LED’s represent the

checkpoints that have been reached

– The Obstacle light is lit when the car sees an obstacle and goes into obstacle avoidance mode, and the Error light is lit if the vehicle finds itself in an unknown state

Dimensions & Blind Spots

Track Following

4 opto-reflectors will be used for track following.

3 are used for forward navigation, and the 4th is used while navigating backwards.

Using 3 sensors allows for quick error detection and correction, as well as efficient turning.

Obstacle Avoidance

Obstacle Avoidance Algorithm

Move forward

Obstacle DetectedNo

Clear on Right

Yes

Yes

No

Turn car until left side sensor sees the obstacle at 12”

Move Forward

Distance < 9” Turn Car Rightyes

Distance > 15”

no

Turn Car Leftno yes

Clear on LeftTurn car until right side sensor

sees the obstacle at 12”

Move Forward

Distance < 9”

Distance > 15”

no

Turn Car Left

Turn Car Right

yes

yes

Yes

Back upNo

Checkpoints

Checkpoints will be denoted by a special pattern in the tape that will be recognized when the vehicle travels over it.

The vehicle will halt at each checkpoint until it receives the user prompt to continue.

An LED will be lit (and remain lit) at each checkpoint, so that at the end of the course, it can be seen how many of the checkpoints were reached.

Track Patterns

Sample Track Layout

Power Consumption

Due to lengthy power-up times of the sensors (especially the distance sensors), all sensors will be powered constantly

Component Current (mA) Voltage (V) Power (W)

HCS12 45 5 .225

Servo Motor 500 5 2.5

DC Motor 1000 9.6 9.6

Opto-Reflectors (4) 35 * 4 = 140 5 .700

IR Distance Sensors (6) 35 * 6 = 210 5 1.05

IC’s/LED’s ? ? ?

Total 1895 + 14.075 +

Testing Strategy

Test each sensor for performance Code review for each major software

component Component testing after SW/HW integration System testing

Testing Strategy (cont’d)

Test vehicle on various track setups Test vehicle under varying light conditions Test various types of obstacles (shapes) Run many iterations of tests to work out

performance bugs

Difficulties

Algorithm to allow vehicle to realign itself with the track after avoiding an obstacle

Reverse navigation

Progress

Project Milestone Expected Completion Date

Design Review Preparation 12-7-2004

Buy and test all other needed components 12-12-2004

Have the vehicle built 1-3-2005

Have the code written and tested as much as possible without being interfaced with the car

1-3-2005

Website Development 2-8-2005

The car can successfully navigate an obstacle free path and recognize stations

1-13-2005

The car can navigate the path and avoid standard obstacles that does not require backing up

1-20-2005

The car can navigate the path and avoid all obstacles including backing up to avoid them

1-27-2005

Testing 2-8-2005

Report Written 2-8-2005

Completed Website 2-8-2005

Poster Completed 2-10-2005

Cost

Part Actual Cost Our Cost Vendor

Vehicle $43.29 $43.29 Toys R’ Us

Colored LEDs ( many ) $10.00 $10.00 Digi-Key

Distance sensors (7) $70.00 $70.00 Online Vendor

Opto-reflectors (6) $40.00 $40 Fairchild

Battery Pack (5V) $15.00 $0 Toys R’ Us

Battery Charger $10.00 $0 Toys R’ Us

HC12 $100.00 $0 CE Department

Servo Motor $5.00 $0 CE Department

Reflective tape (2) $5.00 $5.00 Lowe’s

IC’s $5.00 $5.00 CE Department

Voltage Regulators(4) $4.00 $4.00 Radio Shack

Steering Components $30.00 $30.00 Dan’s Crafts and Things

Miscellaneous Circuit Components $50.00 $50.00 Radio Shack

Miscellaneous $25.00 $25.00 Lowe’s

Total $412.29 $282.29  

Questions?