GEM UNIT Autonomous GEM Vehicle - PowerPoint PPT Presentation

Loading...

PPT – GEM UNIT Autonomous GEM Vehicle PowerPoint presentation | free to view - id: 13b6e-YmNjM



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

GEM UNIT Autonomous GEM Vehicle

Description:

GEM UNIT Autonomous GEM Vehicle – PowerPoint PPT presentation

Number of Views:449
Avg rating:5.0/5.0
Slides: 29
Provided by: cele4
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: GEM UNIT Autonomous GEM Vehicle


1
GEM UNIT! Autonomous GEM Vehicle
  • Adrian Afan
  • Thomas Fong
  • Martin Lizarde Jr.
  • Zaynal Pham
  • June 2nd, 2005

2
Introduction
  • Objective
  • to modify a neighborhood electric vehicle (GEM)
    to autonomously move from one location to another
    while detecting and avoiding objects along the
    way
  • the GEM can be manually controlled via a joystick
    in a drive-by-wire configuration
  • when the desired location is reached, the GEM
    will park itself in a designated parking spot

3
Introduction (Continued)
  • Approach
  • the GEM is guided using x and y mapping via
    Global Positioning System (GPS) and uses a laser
    range finder to detect and avoid obstacles
  • parking will be implemented by utilizing a
    specifically designed object that the vehicle
    will detect and use as a reference point to align
    and park directly in front of
  • The joystick is interfaced to a microcontroller
    to control the vehicle manually

4
Introduction (Continued)
  • The microcontroller will be used to control the
    throttle, braking, steering based on the input
    from the joystick
  • The master controller (laptop) will be used for
    more demanding applications and processing such
    as communication with the GPS, laser range
    finder, digital compass
  • It processes the data to find the desired heading
    of the vehicle toward the destination point and
    the path needed to avoid any obstacles on the way

5
Technical Approach
6
Circuit Schematic
7
Microcontroller Algorithm
  • Acceleration
  • Reacts Linearly to the Joystick Input
  • Joystick increases acceleration when pushed
    forward
  • Speed range is 0 to 15mph
  • Braking
  • Joystick increases braking when pulled backward
  • Can stop vehicle slowly or almost instantaneously

8
Microcontroller Algorithm - Turning
  • Turning
  • Joystick is used as input, steering encoder used
    as feedback
  • Both cover range from 0 to 5V, left to right
  • Voltages are compared for turning
  • If encoder has smaller voltage, wheels are
    signaled to turn right
  • If encoder has larger voltage, wheels are
    signaled to turn left

9
Microcontroller Algorithm - Communication
  • Serial Communication
  • If data is detected on the serial port and the
    joystick is in the neutral position, the vehicle
    will run autonomously
  • Serial data is ignored if the joystick is outside
    of the neutral position
  • ASCII value determine the actions of the GEM
  • Serial data need to be sent in pairs
  • Serial timeout present to prevent microcontroller
    from freezing while waiting for message

10
Autonomous Algorithm
  • System designed to home in on final point
  • Vehicle will go a constant speed unless no paths
    are detected or it has reached the final
    destination
  • Algorithm
  • If ( vehicle is close to the desired location)
  • Tell the vehicle that it has reached the final
    destination and stop the vehicle

11
Autonomous Algorithm - Continued
  • If ( Destination is almost directly North or
    South of vehicle)
  • Assign a predefined desired angle
  • Else
  • Convert the GPS coordinate system into a regular
    XY coordinate system
  • Then the desired angle is calculated using

12
Autonomous Algorithm - Continued
  • Desired angle is converted into the regular
    coordinate system
  • Heading angle is converted into the regular
    coordinate system
  • The difference in the desired angle and the
    heading angle is determined
  • From this difference, the bias path is returned
    to the obstacle avoidance algorithm
  • There are 5 predetermined paths the vehicle can
    take.
  • The bias path is the path toward the destination
    without accounting for obstacles

13
Obstacle Avoidance Algorithm
14
Testing Plan
  • Demonstrate manual GEM control via joystick
  • Tweak microcontroller code for functionality and
    ride smoothness
  • Ensure complete safety of system through testing
    of responsiveness as well as emergency cut-off
    and stopping procedures.

15
Testing Plan - Continued
  • Demonstrate the GEM moving from one location to
    another at the CE-CERT parking lot while
    detecting and avoiding objects
  • Create obstacle map while under manual control
  • Find current GPS location and path to desired
    location while under manual control
  • Allow vehicle to navigate autonomously to desired
    location via GPS without obstacles.

16
Testing Plan - Continued
  • Integrate obstacle map with path planning
    algorithm and find paths around obstacles to
    desired location while under manual control.
  • Full autonomous movement to desired location with
    obstacle detection and avoidance
  • Input multiple destination points into program.
    Vehicle should drive to each point, stop
    momentarily and continue to the next point

17
Results
  • Mechanical Implementation Successful
  • Braking, Throttle and Steering respond correctly
    to joystick inputs
  • Steering Motor Mount does not flex while in use.
    Chain and sprocket are very durable and have no
    slack to add to the steering delay
  • Emergency Brakes have been tweaked to stop the
    vehicle as fast as possible

18
Results - Continued
  • PC Communication with sensors and microcontroller
    work well
  • Laser range finder updates the obstacle map at 1
    Hz
  • GPS and Compass values are updated whenever the
    laser range finder updates
  • Vehicle runs autonomously with little difficulty
  • Vehicle detects obstacles and can maneuver around
    them to follow a clear path
  • Vehicle stops upon nearing the destination

19
Results - Continued
  • Minor Issues
  • Brake controller has a threshold voltage before
    it activates the brakes.
  • The joystick needs to be pulled back about a
    third of the way
  • Causes the braking to be very sudden
  • The steering is slow
  • Takes about 2-3 seconds to get from one side to
    the other
  • Laser Range Finder can only detect objects higher
    than 3 feet tall
  • Can be blinded by bright sunlight at the right
    angle

20
Future Work
  • Improvements to Design
  • Implement Reverse and other car controls into
    Microcontroller
  • Add ability for microcontroller to control
    direction
  • Allows vehicle to back out of traps
  • Buttons on Joystick can be mapped to horn,
    changing vehicle direction, or signaling
  • Add more safety features
  • Throttle cutoff if power to DAC circuit is lost
  • Component Cutoff switches near driver
  • Toggle brake lights when car is stopping

21
Future Work - Continued
  • Parking
  • Identify special obstacle and park in front of it
  • Update Faster
  • Stabilize the code for updating the obstacle map
    at 5Hz
  • Creation of PCB for DAC circuit
  • PCB has already been designed
  • Need to fix pin assignments
  • Improved Path Planning and Obstacle
    Identification Algorithms

22
Future Work - Continued
  • Application for Future
  • Identify an obstacle and follow it
  • Expansion to larger vehicle and system to compete
    in DARPA Grand Challenge
  • Next Slide Video
  • Focus on the two stationary GEM vehicles
  • Notice how it avoids the first one by turning
    right and then avoids the second one by turning
    left
  • After the vehicle passes the obstacles, it
    realigns with the destination point and heads
    towards it
  • Vehicle stops very close to the desired
    destination point marked by the cone

23
Video
24
Pictures
  • (From Left to Right) Martin Lizarde, Thomas Fong,
    Adrian Afan, Zaynal Pham
  • Special Thanks to Dr. Barth, Dr. Beni and all the
    people who helped us with this project!
    G-g-G-gem unit

25
Appendix A - Budget
26
Appendix B - Cost Analysis/Alternate Solutions
  • Electro-Hydraulic Brake Controller
  • While it stops the vehicle very well, it is not
    smooth as originally assumed to be
  • Possibly because a dedicated brake controller
    with an internal accelerometer was not purchased
    with the system
  • Could be replaced by a linear motor operating the
    master cylinder
  • This would be smoother, but would need feedback
    to get proper braking

27
Appendix B - Cost Analysis/Alternate Solutions
Continued
  • SICK Laser Scanner
  • Provides a very accurate map of surroundings that
    it can see
  • Does not see small objects that fall underneath
    its field of vision
  • Needs to be supplemented by ultrasonic sensors
  • Cannot be replaced by ultrasonic sensors because
    they lack the range given by the laser scanner
  • Can be replaced by computer vision
  • Faster computer would be needed with good
    obstacle detection algorithms

28
Appendix B - Cost Analysis / Alternate Solutions
- Continued
  • Steering Motor
  • Faster Motor with Similar Torque
  • This would increase responsiveness of steering
  • Small amount of space available around mounting
    point
  • Could be replaced with Linear Motor
  • Would need to be very strong to move tires
  • Novel mechanical mechanism could multiply force
    exerted on tires and ensure that the physical
    limits of steering mechanism are not violated
About PowerShow.com