gps-guided autonomous vehicle
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GPS-Guided Autonomous Vehicle
http://cegt201.bradley.edu/projects/proj2001/gpscarjb/
GPS-Guided Autonomous Vehicle
Presentation Overview
• Project Summary• Project Goals• What is GPS? • Block Diagram• Project Subsystems
– Hardware Components– System Inputs– Software Functionality
• Timeline• Final Results• Cost Analysis
GPS-Guided Autonomous Vehicle
Project Summary
The goal of this project is to design and build a vehicle that will be able to navigate from one location on Bradley University's campus to another along the sidewalks without human intervention. In order to do this we have decided to implement a global positioning system (GPS) as the means by which the vehicle will know its position. Heading from a digital compass will be used in conjunction with position information from the GPS receiver to steer the vehicle.
GPS-Guided Autonomous Vehicle
Project Goals
• Integrate a control system on a self-propelled vehicle utilizing GPS
• Implement all controls using a low-cost microprocessor and GPS receiver
WHAT IS GPS?
GDOP (Geometric Dilution Of Precision) Components: PDOP = Position Dilution of Precision (3-D). HDOP = Horizontal Dilution of Precision (Latitude, Longitude). VDOP = Vertical Dilution of Precision (Height). TDOP = Time Dilution of Precision (Time). .
GPS-Guided Autonomous Vehicle
Sample of DGPS data
Horizontal
Standard
Deviation :
104.9 meters
GPS-Guided Autonomous Vehicle
Sample of DGPS data
Horizontal
Standard
Deviation :
2.3 meters
GPS-Guided Autonomous Vehicle
GPS Module
• Problems With Differential GPS– Accuracy was not improved, and sometimes
even reduced• Correction signal is transmitted over a range that
adds error. ( 1m error for every 100 km (62 miles) )
• Maximum broadcast range = 450 km (280 miles)
• Signal latency can be as great as 3 to 5 seconds
• Correction signal and receiver signal are determined by different clusters
GPS-Guided Autonomous Vehicle
The Solution
• Dead-Reckoning
– Uses a digital compass to account for the errors of GPS.– Normally used while satellites are not visible.– We are incorporating this concept by using the compass to control the steering.
GPS-Guided Autonomous Vehicle
• 2 degree accuracy, 1 degree resolution• 5Hz sampling rate (software down-sampled to 1Hz)• Pin selectable BCD or binary output format• Power supply: single 5 volt• Size: 1.5"l x 1.3"W x 0.4"H• Weight: 0.2 lbs.
Digital Compass
GPS-Guided Autonomous Vehicle
Main Project Breakdown
• Components– Power Circuitry
• Steering control / Linear Actuator
• Drive Motors
• Subsystems– Digital compass– GPS
• Software – Autonomous mode– Diagnostic mode
GPS-Guided Autonomous Vehicle
Block Diagram
GPS Signal
Potentiometer Feedback
LMD18200(H-Bridge)
PowerCircuitry
Drive Motor
Linear Actuator
GPS Receiver
EMACBoard
Battery 1
Keypad
LCD Display
Digital Compass
Battery 2
GPS-Guided Autonomous Vehicle
Disciplines Involved
• Power electronics
• Microprocessor controlled feedback systems
• DC Motors
• GPS and Differential GPS– RF related interferences
• Cross compilers using Assembly and C-code
GPS-Guided Autonomous Vehicle
Hardware Components
Steering and Drive circuitry
GPS-Guided Autonomous Vehicle
Drive Circuitry
•Optically Isolated
•12 Volt Bias Supply
•Drives Two Motors In Series
•Delivers 40 Amps Max Current
•Pulse Width Modulated Control Signal
GPS-Guided Autonomous Vehicle
Drive Circuitry
+5v+12v
+12v
+12v
From the P
+12v
GPS-Guided Autonomous Vehicle
Voltage Spike
13V
25V
GPS-Guided Autonomous Vehicle
Steering Circuitry
•H-Bridge Integrated Motor Controller–includes
•Bi-directional input control•Brake Control•PWM input
•Linear Actuator Attached To The Steering Rod
•PWM Controlled Rate of Change
•Potentiometer Feedback Position Control
GPS-Guided Autonomous Vehicle
Steering Circuitry
+12V
+5V
1
2
3
4
5
6
7
10
11L
MD
1820
0T
10nF
10nF
Dir
Brake
PWM
Feedback
GPS-Guided Autonomous Vehicle
Steering
Drive
GPS-Guided Autonomous Vehicle
GPS
Ashtech G8
Compact OEM GPS Module
GPS-Guided Autonomous Vehicle
GPS Module
• Completed– Serial Communication between EMAC and G8– Data acquisition using GPS and DGPS– Acquiring position information
GPS-Guided Autonomous Vehicle
Summary of GPS Results
• Accuracy varying from 5m to 50m
• GPS Heading and velocity accurate only at >2.5 mph.
• Accurate position requires up to four hours of stationary data acquisition.
GPS-Guided Autonomous Vehicle
Digital Compass Schematic
5V regulated
ground
P4.3
P1.7
P1.4
ground
5V regulated
ground
P4.4
GPS-Guided Autonomous Vehicle
Software Control
Using C-code cross-compiler
in Keil programming environment for 8051
GPS-Guided Autonomous Vehicle
Software System Description
• Steering Control– Sends control signal to actuator to steer towards
the desired heading.– Limited to 5 mm of actuator movement per 1
second cycle. (About 3 deg.)
GPS-Guided Autonomous Vehicle
• Drive Control– Begins with an 40% (fast) duty cycle to
overcome initial vehicle inertia.– Maintains a constant duty cycle of 30% (slow)
at 100Hz over the course of travel to the motors giving a speed of approximately 1 mph.
Software System Description
GPS-Guided Autonomous Vehicle
Software Function• Modes of Operation
– Diagnostic Mode• 2 Speed Controls
– (fast) and (slow)
• Manual Steering Controls Through the 80535– left and right (5 mm actuator increments)
– Autonomous Mode• Automatic Speed Control
– larger duty cycle to overcome inertia, then slower velocity
• Automatic Steering Control– based on digital compass error signal
• Automatic Break With GPS Coordinates
GPS-Guided Autonomous Vehicle
SEM_WEEK ACCOMPLISHED1_1 Component Reasearch1_2 Component Selection1_3 Acuator Testing / GPS Research1_4 GPS Research
winter break Actuator Design / GPS Testing / Code Building2_1 Code Building / GPS Testing / Actutor Testing2_2 Actuator Mount / GPS Testing / Code Building2_3 GPS Testing / Code Building2_4 Drive Circuitry Design and Testing2_5 Differential GPS Testing / Drive Circuitry2_6 Final Code for GPS and Circuit Assembly2_7 DGPS Testing within Sytem2_8 Digital Compass Interrupt / Code Rebuilding2_9 Digital Compass Testing and Implementation2_10 Code Debugging / Vehicle Testing2_11 Code Debugging / Vehicle Testing Outside2_12 Student Expo / Final Testing
Project Timeline
GPS-Guided Autonomous Vehicle
Final Results
MPEG of vehicle driving, and stopping
GPS-Guided Autonomous Vehicle
GPS-Guided Autonomous Vehicle
Electronics
GPS-Guided Autonomous Vehicle
GPS Sensor
GPS-Guided Autonomous Vehicle
Antenna
GPS-Guided Autonomous Vehicle
Actuator
GPS-Guided Autonomous Vehicle
Cost Analysis
Part CostJameco Digital Compass $44.95Peg Perego Gauch Grande $399.99EMAC 80535 $379.95G8 GPS Receiver incl. Evaluation kit $475.00 (without evalution kit) [$98.00]Linear Actuator $95.00H-Bridge $20.00IRFP240 (2) drive circuit $8.02Additional passive/active components $10.00
Total Cost $1,432.91[total cost with OEM module, not evaluation kit] $1,055.91
GPS-Guided Autonomous Vehicle
Special Thanks To:• Dr. Brian Huggins
– Advisor, Customer, and technical writing editor• Dr. In Soo Ahn
– Advisor/GPS expert• Mr. Chris Mattus
– EMAC guru, connection specialist (and photo editor)• Nick Schmidt
– The do-it-all man • Prof. Steve Gustchlag
– Power genius • Dr. Gary Dempsey
– Cross-Compiler Master
And finally...
GPS-Guided Autonomous Vehicle
•
– For their support and sponsorship of the GPS-Guided Autonomous Vehicle
GPS-Guided Autonomous Vehicle
ANY QUESTIONS?
GPS-Guided Autonomous Vehicle