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GPS Guided Vehicle with Automatic Obstacle Avoidance

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  1. GPS Guided Vehicle with Automatic Obstacle Avoidance ECE 445 Senior Design Project - Group 19 Joe Meng & Kevin Hsieh TA: Tomasz Wojtaszek November 29, 2007

  2. Outline Introduction Features Hardware Overview Software Overview Challenges, Explanations, and Solutions Future Developments Ethical Considerations Summary

  3. Introduction A mini DARPA Grand Challenge vehicle Designed to maneuver towards desired destination through various obstacles

  4. Features PSoC (Programmable System-on-Chip) R-232 Serial between GPS and PSoC Ability to prevent endless looping during obstacle avoidance Adjustable motor speed control

  5. System Overview Hardware: PSoC, GPS, Motor unit, sensor units Software: GPS data retrieval, main control algorithm

  6. System Overview GPS unit PSoC Motor units Sensor units

  7. AutomatizedMonster Truck Motor unit PSoC GPS unit Sensor Groups

  8. Hardware Overview GPS unit: Garmin GPSmap® 76Cx Sensor units: Detection of obstacles PSoC: Cypress CY8C29466-24PXI, CY3210-PSoCEval1 Motor units: Vehicle movements

  9. Can be connected to PSoC through RS232 Updates every second Using NMEA sentences Provides positional information and direction guidance Garmin GPSmap® 76Cx

  10. GPS (Testing) Use Microsoft Hyperterm to read GPS output sentences Compare self-acquired sentences with the actual output sentences

  11. PSoC • PIC microprocessor • R-232 serial with GPS • digital and analog input for sensor units • digital and analog output for motor units

  12. PSoC (Schematic)

  13. Sensor Units 3 front sensors, two side sensors for obstacle detection Analog output Adjustable detection distance through comparators

  14. Sensor Units (Schematic)

  15. Sensor Units (Testing) Measure output voltage from various distances Generate Vref, pass into comparator Check for successful digital output

  16. Sensor Units (Results) Sonar EZ-4 Side Sensors GP2D120 Front Sensors GP2Y0A02YK

  17. Sensor Units (Results)

  18. Sensor Units (Results)

  19. Sensor Units (Results)

  20. Sensor Units (Results) Front Sensors: n = -175, Vout = 0.652v, 80cm guarantee Side Sensors: n = -150, Vout = 0.861v, 15cm guarantee • Sonar: Vin = 0.315 · 8 (PGA gain) = 2.52v, if (n < 9529), 80cm guarantee

  21. Motor Units • 3Vdc power supply • Current: 500 mA • Use FET to control speed • Use MUX to control direction

  22. Motor Units (Schematic)

  23. Motor Units (Testing) Search for input power according to desired vehicle speed (~2mph) Use linear region of MOSFET to control current flow

  24. Motor Units (Results) @2mph: Vin = 3V, Iin = 500mA, Power = 1.5W

  25. Software Overview Inputs: 4 IR sensors, 1 Ultrasonic sensor, and GPS data Outputs: Drive motor control, Directional motor control Code blocks: GPS datapoint extraction Main control algorithm

  26. GPS Datapoint Extraction NMEA sentence acquisition Parameter extraction and conversion

  27. Main Control Block System initialization Course adjustment Dealing with obstacles Parameter updating

  28. Obstacle Detection Sensors are only method of obtaining information about environment Obstacle categorization and differentiation

  29. Obstacle Avoidance Priority given to easiest method of avoidance Use GPS values to assist determining easiest method if sensor data is insufficient Sensor usage Generation of an "obstacle log"

  30. Getting to the Destination GPS checking Changing speed Obstacle detection Nearing destination

  31. Exceptions Sensors are insufficient in accounting for all possible situations Assumptions made Obstacle positioning Destination is clear Improvements

  32. Challenges Problem: GPS positioning precision No information on destination bearing Explanation: Weak satellite signal Need to use indirect calculation Solution: GPS with information on destination bearing, specifically GPBWC (even better with autopilot function)

  33. Challenges Problem: Spontaneous glitches during obstacle detection Leads into false subroutines Explanation: Unsecured circuit connection with PSoC Unsuccessful object detection during sensoring cycles Solution: Replace PSoC components Change sensors

  34. Future Improvements Needed a more robust obstacle recognition system GPS guidance works better with long distance The ability to interact with and learn from the environment

  35. Ethical Considerations How are unmanned vehicles going to be used? To what extent do engineers share the responsibility?

  36. Summary System integration difficulties Importance of modular testing

  37. Credits Architecture and Programming of PSoC Microcontrollers GPS Serial Communications DC motor speed controller Miscellaneous PSoC inquiries NMEA Sentences

  38. The End Thank you