Design and Evaluation of an Adjustable Ackermann Rate Steering System for Formula Student Racing Cars

FSAE is a competition designed to maximize car performance, in which the steering system is a key subsystem, and the steering system performance directly affects the cornering performance of the car. The driver relies on the steering system for effective handling, which is also crucial for cornering and achieving faster lap times. Therefore while improving the performance of the steering system, it is crucial to match the vehicle design to the driver's habits. Traditionally, steering systems typically use an Ackermann rate between 0% and 100% to offset the slip angle caused by tire deformation, thus achieving the purpose of reducing tire wear. Tests have shown that a 40-60% Ackermann rate provides a similar compensation effect with little difference in tire wear. The traditional steering design method also does not consider the driver's driving habits and feedback, which is not conducive to the improvement of the overall performance of the car. In FSAE's figure-of-eight loops and high-speed obstacle avoidance courses, the need to balance steady-state and transient performance poses a challenge to traditional designs. This paper presents an adjustable Ackermann rate steering system for Formula Student Racing Cars. By selecting an Ackermann rate between 40% and 60%, we employed a comprehensive approach to analyze and optimize the system. We used Adams/Car software to analyze the steady-state and transient performance differences of the steering system, while CarSim software was utilized for vehicle model simulation to further analyze performance variations. The design was refined through a dedicated steering knuckle and a disconnected joint, allowing for Ackermann rate adjustments based on driver feedback. To further validate the design's effectiveness, we applied it to the 2024 WUTE team of Wuhan University of Technology and participated in the Formula China Student Electric Race (FSEC). Through a combination of simulation and human-car-track closed-loop experiments, we demonstrate that this design significantly enhances the overall performance of the vehicle and improves steering adaptability across different track configurations.