Autonomous Golf Cart DREW GAYNOR, TYLER LATHAM, IAN ANDERSON, CAMERON JOHNSON ADVISORS: DR. DAVID MIKESELL AND DR. FIRAS HASSAN

Requirements  Travel to a destination selected by a user  Select the best route to the chosen destination  Accurately follow this planned path along campus roads and sidewalks  No other user input required during trip, except in the case of an emergency  Transport passengers safely  Detect obstacles and avoid collisions  Stop immediately if an inadvertent collision occurs  Provide emergency stop buttons

System Overview

Acceleration System Block Diagram  Pre-autonomous mode:  Binary signals for direction and enable come from cart  The analog signal for speed is sent from the potentiometer wiper arm on the pedal to the speed controller  Normally open switches

Acceleration System Block Diagram  Autonomous mode:  Binary signals for direction,enable, and analog output speed are calculated in LabVIEW program  Acceleration relay pushbutton closes the relays(puts cart in autonomous mode)  Binary signals are sent from the Relay module to speed controller  Cart speed signal is sent from Analog Output module to speed controller

Steering System Block Diagram  Pre-Autonomous mode:  The cart’s heading is controlled by the steering wheel on the cart

Steering System Block Diagram  Autonomous mode:  The clutch pushbutton is pressed which disengages the steering shaft and allows the servo motor to steer the cart  The relay is closed so the amplifier is enabled and the cart is in autonomous mode  The heading has been calculated in LabVIEW and is outputted to the amp from the Analog Output module

Steering System Block Diagram  Amp will amplify the signal and then send it to the filter card to add inductance.  This signal is passed to the Servo motor which steers the cart.  The encoder output or position of the servo motor is then sent back to the Servo module

Java Application Switch modes Choose destination Autonomous start/stop button: drives to destination or cancels current trip Position adjustment controls: offset GPS position drift or other error

Java Application Cart (always centered) Path points Destinations (nodes)

GPS/Inertial  Project’s OXTS RT2500 GPS unit has a stated accuracy for position values of 2-3 meters  We were able to get an OXTS RT3002 on loan: much more accurate than RT2500

Path Following Results Travelled autonomously from Biggs loading dock to Kinghorn northwest doors with RT3002 Route shown in yellow Data collected with RT3002 Collected more But focused on this route

Path Following Results Collected path data shown in blue Actual route navigated shown in red Followed route fairly accurately On right of graph, consistent gap probably due to drift Position adjustment controls designed to account for this

Path Following Video (Video removed to reduce file size. Original video can be retrieved from project website)

LIDAR (Light Detection and Ranging) Housing tilted downward Angle resolution: 0.5 degrees Baud rate: (Sampling rate = 4Hz)

Speed Reduction

Detection Field (Wheels turned < 8°)

Detection Field (Wheels turned > 8º)

Collision Avoidance Video (Video removed to reduce file size. Original video can be retrieved from project website)

Complete System Video (Video removed to reduce file size. Original video can be retrieved from project website)

Questions?

Potential Future Improvements  Weatherproofing: isolation of electronics under the hood  LIDAR  Housing  LMS 511  GPS: RT3002 differential GPS  Wiring: automotive wiring harnesses  Zippswitch

Speed Reduction Algorithm