MARTY

Introduction

MARTY is the Dynamic Design Lab's autonomous electric drifting DeLorean. It has been extensively modified to serve as a flexible testbed for control algorithms at and beyond the limits of handling.

The stock engine has been replaced by a 400HP/740V Renovo electric drivetrain that powers the rear wheels. A bespoke electric power steering system allows for computer control of the front steering angle. MARTY is also equipped with a Brembo brake-by-wire system that can control the brake pressure on each wheel independently. A dual-antenna GPS/inertial navigation sensor fusion system is used to measure the position, velocity, and angle of the vehicle.

While the DeLorean is a cultural and design icon, it was never regarded, even in its time, as a particularly capable vehicle. To conduct these experiments, we had to dramatically improve the dynamic performance, tunability, mechanical robustness, and safety of the vehicle. We completely overhauled the suspension, steering, and interior with a combination of custom-designed and off-the-shelf components.

We would like to thank The Stanford Revs Program, Stanford CARS, Bridgestone, Brembo, Renovo, and Paccar for their generous support of MARTY's development and continued operation.

Major Features

MARTY is a continuously evolving active test bed. This page describes MARTY as specifically manifest in the PhD thesis Automated Vehicle Control Beyond the Stability Limits.

Electric Drivetrain and Steering Actuation

MARTY is equipped with a powerful and responsive electric drivetrain. The 400HP of available system power allows access to a wide range of drifting conditions: fully-autonomous tests have been conducted at speeds of up to 60km/h at 40 degrees of sideslip.

The steering angle is actuated through a bespoke electric power assist system. MARTY can steer lock-to-lock through it's full range of +/- 38 degrees in under a second, enabling rapid drifting transitions.

Suspension and Steering Modifications

The DeLorean's suspension and steering has been extensively modified to improve adjustability, performance, and mechanical robustness. We designed custom control arms and uprights, installed coilovers on all four corners, and fit an aftermarket steering rack.

MARTY is also equipped with a prototype Brembo brake-by-wire system which allows for fast independent control of each wheel. Upgraded calipers and rotors ensure ample stopping force is available in all test conditions.

Measurement and Compute

In order to know where it is, and how fast it is moving, MARTY uses an off-the-shelf GPS/internal navigation sensor fusion system. Two antennas, one on each side of the roof, allow for accurate measurement of the angle of the car body which is critical for drifting.

Hundreds of times a second, in response to these measured changes in the vehicle's position and angle, onboard computers then calculate the steering and throttle adjustments required to keep the car drifting on the path.

Rollcage and Interior Modifications

To bring the DeLorean up to modern track vehicle safety standards and improve torisional stiffness, a rollcage was added. Race seats and six-point harnesses were also installed.

The redesigned interior enables the operators to safely oversee autonomous testing. This is manifest in the design and placement of the physical control interface, as well as the clean aesthetic that minimizes distraction.

Contributors

From 2012 to 2019, MARTY was built and continuously improved by a passionate and dedicated team from the Dynamic Design Lab and beyond. This project was overseen and guided by Prof. Chris Gerdes.

MARTY was primarily developed by a team of Stanford students, which varied in size over the 7 years:

Jon Goh, PhD, 2012-2019
Tushar Goel, PhD Candidate, 2015-Current
Shannon McClintock, Undergraduate/Masters, 2012-2015
Arni Lehto, Masters, 2013
Wyles Vance, Masters, 2013
Phill Giliver, Undergraduate, 2013 and 2016
Michael Carter, Undergraduate/Masters, 2015-2016
Joe Sunde, Undergraduate/Masters, 2016-2017

Working on this testbed, from mechanical design and fabrication to electronics integration, has been an invaluable practical learning experience for all of us. We would like to thank the Stanford Undergraduate Research Institute (SURI) program for sponsoring Shannon, Phill, Michael, and Joe's first summer on the project.

The electric drivetrain installation was a cooperation between Stanford and Renovo. Since then, Renovo has continued to support the MARTY project by lending their time and invaluable experience. Aaron Sellars, Matt Brunner, Jason Stinson, Chris Heiser, Nick Hori, Mike Vogel, Conor Sullivan, Elmar Grom, Ivan Pandev, Savion Ragster, and Owen Davis were an indispensable part of the team.

The development process was greatly assisted by experienced industry partners. This includes Terence Wei from Bridgestone, and Beniamin Szewczyk, Marco Pagni, Valerio Galizzi, and Alessandro Rossi from Brembo. MARTY was realized with the generous support of the Revs Program at Stanford, the Stanford Center for Automotive Research (CARS), Renovo, Bridgestone, Brembo, and PACCAR.

In particular, MARTY would not have been possible without the experience and guidance of Aaron Sellars. Aaron, you were an incredible colleague, friend, and mentor, with a zest for life and adventure matched only by your kindness and patience. You will be sorely missed by all.