Autonomous Golf Cart

A low-cost drive-by-wire research platform for sim-to-real autonomy

Jacob Igo

Arizona State University

MS Computer Science Thesis - Work in Progress

Speed, then brake, October 18, 2026. Testing the throttle and speed chain after being integrated with the braking system.

Now: measured stopping tests. Next: a hardwired e-stop.

First drive-by-wire, September 12, 2026. A command typed on the laptop turns the wheels at various speeds, with the cart on jackstands.

Overview

Self-driving research vehicles are expensive, and most of them are closed. This project turns a used Yamaha G22E electric golf cart into an autonomous research platform built from off-the-shelf parts. It adds a software-controlled drive-by-wire layer to the cart without changing how it drives for a person behind the wheel.

The cart is the physical end of a graduate research project on moving autonomy software from simulation onto real hardware. Everything below is the platform that work runs on.

System

A strict split keeps the safety-critical parts simple. Linux computers are fast on average but can stall unpredictably, so the Linux computer only plans. A bare-metal microcontroller handles every electrical connection to the cart and enforces limits. Relays sit underneath everything and fall back to stock wiring whenever power is lost.

Plan Raspberry Pi ROS 2 Jazzy
USB serial
Act Teensy 4.1 Watchdog · slew limits
SPI
Inject Digital pot Stands in for the pedal sensor
relay
Stock Motor controller Unmodified
Planned RTK GPS on the cart Perception Steering actuator Hardwired e-stop
Throttle path as built. The digital potentiometer imitates the cart's original resistive pedal sensor, so the stock controller sees exactly the signal it expects. When the relays lose power they drop out, and the cart goes back to its own pedal. The loop closes through the cart's own motor speed sensor, which the microcontroller reads to measure how fast the wheels are turning. Braking is a separate path: a linear actuator presses the brake pedal directly, and the microcontroller reads its position back. It pushes on the pedal but is never attached to it.

Failsafes, tested with the wheels turning

The relay cut and the watchdog were both proven on the bench before going on the cart. On the cart, all three failsafes were triggered while the wheels were spinning under software command, and each one stopped them. That was also the first time the accelerator interlock had been tested at all.

01

Relay power cut

Cutting relay power drops the throttle injection and hands the throttle back to the stock pedal circuit. No software is involved.

02

Link lost

Pulling the USB cable mid-command sets off the microcontroller's hardware watchdog, which returns the throttle to rest.

03

Human interlock

A safety operator holds the accelerator switch closed. When they let go, the stock controller stops the cart, whatever the software is commanding.

The brake follows the same rules. It cannot press while the throttle is open, and it has to let go before the throttle can return. If the link to the computer drops, the brake holds where it is instead of letting go, a choice that gets revisited before any test on the ground.

Build

White Yamaha G22E golf cart with its rear on a red jackstand, electronics and a laptop on the floorboard
The Yamaha G22E, rigged for its first drive-by-wire test
Breadboard with a Teensy microcontroller, digital potentiometer and relays, wired to a laptop
Bench testing the drive-by-wire electronics
Jacob giving a thumbs up behind the cart, with the breadboard and laptop on the floorboard
Test day
A soldered prototype board with a Teensy microcontroller, relays and terminal blocks, sitting on the cart's rear floor among zip-tied wiring, with the battery pack above
The soldered board, on the cart
A linear actuator bolted to a wooden plate on the cart's floor, its rod pointing at the brake pedal
The brake actuator, test-fit against the pedal
Jacob sitting beside the cart with a laptop, seen under the cart bed, with the electronics bay visible behind
Running a test from the laptop

Progress

Hardware comes up one step at a time. Each stage adds one real component to the loop and has to pass before the next one starts.

  1. Aug 24, 2026

    Stage 0: Software alone

    A simulated serial link and a record-and-replay roundtrip, with no hardware attached.

  2. Sep 1, 2026

    Stage 1: Computer ↔ microcontroller

    The link works, using a custom binary protocol with CRC framing. Fault handling, including the hardware watchdog, was measured on the real board. The remaining fault cases can only be tested in later stages.

  3. Sep 1, 2026

    Stage 2: Signal injection

    The microcontroller drives the digital potentiometer, checked against a meter. First end-to-end command from ROS to the output.

  4. Sep 9, 2026

    Stage 3: Controller on the bench

    A resistor rig simulated the cart's controller on the bench, and every acceptance criterion was measured and passed.

  5. Sep 12, 2026

    Stage 4: On the cart

    With the cart on jackstands, the wheels turned under software command. All three failsafes stopped them mid-motion, and afterward the cart was put back to stock.

  6. Sep 26, 2026

    Commanded speed

    The microcontroller now reads the motor's speed sensor. Measuring how throttle maps to wheel speed gave a simple linear fit, which the controller uses as its first guess for any requested speed. A feedback loop corrects the rest. Tuned on jackstands, it reaches a new speed in about half a second without oscillating.

  7. Sep 27, 2026

    RTK GPS at the test site

    A walked survey of the driving area held a centimeter-level fix for over 90% of the run. With commanded speed, this closes the first milestone gate.

  8. Oct 18, 2026

    A permanent board

    The electronics moved off the breadboard onto a soldered board, and it went on the cart. The wheels turned under commanded speed again, and the failsafes held: cutting relay power stopped them, and the link-loss cutoff fired within about a tenth of a second. It was still powered from a lab supply.

  9. Oct 4 – 18, 2026

    Braking: the actuator

    A linear actuator presses the brake pedal. It was brought up the same way as the throttle: on the bench, test-fit on the cart, then added to the cart's firmware. The speed-then-brake sequence now runs from one command, interlocked with the throttle.

  10. Later

    Steering, autonomy

    The steering actuator, then the full autonomy stack on the cart.

A note on safety

This is a research platform tested on private property, with a safety operator present and speeds capped. It is not intended for public roads. All testing to date has been done with the drive wheels off the ground.