Download PT 5000

PT 5000
Pooja Rao
Ted Tomporowski
December 7, 2004
Functional Overview
To create an autonomous vehicle that is capable of:
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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
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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
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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
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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
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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
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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
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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
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Two buttons are present
–
–
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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
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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
No
Obstacle Detected
Yes
Clear on Right
Turn car until right side sensor
sees the obstacle at 12”
Yes
No
Yes
Turn car until left side sensor
sees the obstacle at 12”
Clear on Left
Move Forward
Move Forward
Turn Car Left
yes
Back up
Distance < 9”
Distance < 9”
no
Turn Car Right yes
No
Distance > 15”
yes
Turn Car Right
no
no
Distance > 15”
yes
Turn Car Left
Checkpoints
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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
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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
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Test each sensor for performance
Code review for each major software
component
Component testing after SW/HW integration
System testing
Testing Strategy (cont’d)
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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
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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
Website Development
1-3-2005
The car can successfully navigate an obstacle free path and
recognize stations
The car can navigate the path and avoid standard obstacles
that does not require backing up
The car can navigate the path and avoid all obstacles
including backing up to avoid them
Testing
1-13-2005
Report Written
2-8-2005
Completed Website
2-8-2005
Poster Completed
2-10-2005
2-8-2005
1-20-2005
1-27-2005
2-8-2005
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
Miscellaneous Circuit Components
$50.00
$50.00
Dan’s Crafts and
Things
Radio Shack
Miscellaneous
$25.00
$25.00
Lowe’s
Total
$412.29
$282.29
Questions?