Pathfinder - Rochester Institute of Technology

Report
Pathfinder
John Callaghan
Rex Lam
Objective
To travel towards a destination
while avoiding any obstacles.
Main components
The pathfinder
Obstacles
Beacon
Pathfinder top view
Tank (Overhead View)
Photodetector with Servo
Proximity Sensors
Pathfinder side view
Tank (Side View)
Photodetector with
Servo
Proximity Sensors
Optoreflector
Beacon/Obstacle Description
Beacon’s IR emitters must not be
occluded by obstacles
Consists of eight emitters surrounding
the beacon cylinder
For simplicity, the obstacles will be
rectangular in shape and high enough
to pose a threat for the tank
Hardware utilized
Proximity sensors
Photo detector
IR emitters
Opto-reflector
Chassis and DC motors
H-Bridges
Battery
Proximity sensors
Sharp GP2D15 IR
Proximity Sensor
Range between 10 cm
and 80 cm
Beam width of 45-50°
This particular model yields a digital output when an
object is within 5” (preset at 24 cm)
No external circuitry is needed
Photodetector
Panasonic PNA4612
Photodetector
Maximum range of 11-16
meters
Carrier frequency of 38 kHz
No external circuitry required except for noise filtering
IR Emitters
Panasonic LN64 PA IR emitter
Beam width of 45°
Wavelength of 950 nm
Eight of these located within independent beacon
system
Opto-reflector
Optek OPB745 opto reflector
Responsible for informing that
the vehicle has arrived at the
beacon
The beacon is encompassed by reflective tape, and
modifications are done on the signal handling circuit
that was completed previously (IDE).
Chassis and Actuators
Robot Tank by Budget Robotics
Dimensions: 6.5” X 4.25” X
3.75” height
Two gear ratio to choose from:
58:1 , 203:1
Battery and power
4 AA sized battery for the vehicle
4 AA sized battery for the beacon
H bridges will be responsible for
interfacing the DC motors to the HCS12
Block Diagram
DC Motor
HCS12
H bridges
PT 0-5
DC Motor
Servo
Photodetector
IR Sensors
Software (Algorithm)
Power
On
180
degree
scan
Fail to locate
beacon
take a
180 turn
Vehicle rotate to
face the beacon
Avoidable
No Obstacle
Move forward
Obstacles detected
Opto Reflector found tape
Perform
avoidance
Objective
Accomplished
Trapped
Operation
halted
User interface
On/Off
Destination
Moving
Error
Difficulties
To find the way out when it runs into a
U-shaped obstacle
Calibrating the opto reflector correctly
because it has been known to be
unreliable
Cost
Item
Cost
Quantity
Total
Remote Control Tank
$33.00
1
$33.00
Sharp GP2D15 Infrared Ranger
$13.50
6
$81.00
Optek OPB745 Optoisolator
Free
1
$0.00
PNA4612 MOOYB Photodetector
$1.43
2
$2.86
LN64PA IR Emitter
$0.91
10
$9.10
LM298 H Bridges
$4.95
1
$4.95
HCS12 Microprocessor
$180
1
$180.00
Miscellaneous Circuitry
NA
NA
$30.00
Grand Total
$340.91
Questions?

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