Longitudinal Control for Autonomous Racing with Combustion Engine Vehicles

TL;DR

The paper addresses the challenge of converting high level trajectory commands into low level throttle, brake and gear commands for autonomous racing with combustion engine vehicles. It introduces a modular longitudinal control framework comprising a gear shift controller, brake warmup, and a high frequency longitudinal controller, with ABS and TC for safety. Validation is performed using real world Abu Dhabi Yas Marina race data and high fidelity simulation, showing close tracking of acceleration targets and safe braking under varying tire road conditions. The work provides an open source implementation and discusses future work to extend safety with an electronic stability program.

Abstract

Usually, a controller for path- or trajectory tracking is employed in autonomous driving. Typically, these controllers generate high-level commands like longitudinal acceleration or force. However, vehicles with combustion engines expect different actuation inputs. This paper proposes a longitudinal control concept that translates high-level trajectory-tracking commands to the required low-level vehicle commands such as throttle, brake pressure and a desired gear. We chose a modular structure to easily integrate different trajectory-tracking control algorithms and vehicles. The proposed control concept enables a close tracking of the high-level control command. An anti-lock braking system, traction control, and brake warmup control also ensure a safe operation during real-world tests. We provide experimental validation of our concept using real world data with longitudinal accelerations reaching up to $25 \, \frac{\mathrm{m}}{\mathrm{s}^2}$. The experiments were conducted using the EAV24 racecar during the first event of the Abu Dhabi Autonomous Racing League on the Yas Marina Formula 1 Circuit.

Figures (9)

• Figure 1: Dallara EAV24 racecar of the TUM Autonomous Motorsport team at Yas Marina Circuit in Abu Dhabi
• Figure 2: Structure of the longitudinal control system
• Figure 3: Predictive gear shift controller functionality. The gray shaded area indicates the lookahead horizon. The green parts mark the region where a shift is required but not executed because of high lateral accelerations.
• Figure 4: Internal structure of the longitudinal controller
• Figure 5: ABS functionality. The gray shaded area indicates the active ABS intervention.