The Effect of Active Wheel Load Transfer on Formula Student Cars

Active suspension is commonly considered an effective way to improve ride, handling, overall vehicle posture, and stability. The lap time of racing cars with active suspension is expected to be improved, for which loads of four wheels will be well allocated and the performance of all four tires will be maximized. From the perspective of Active Wheel Load Transfer (AWLT), this paper investigates how active suspension adjusts the load on four wheels to impact lap time. In this study, a minimum lap time optimal control problem is presented, which relaxes the wheel load transfer constraints and introduces different AWLT to investigate the improvements and optimal AWLT. The simulation results of the three scenarios, a corner, coupled corners, and track are utilized and analyzed. Simulation results of the complete track show that the lap time of the FSAE car can be 0.5%–3% faster with AWLT, and simulation results of different corners illustrate the impact of AWLT on the performance of the FSAE car. In low-speed corners, AWLT can improve braking performance and steering sensitivity by increasing front axle grip during corner entry. During corner exit, AWLT can increase rear axle grip to allow the car to keep higher lateral acceleration at substantial throttle input. In high-speed corners, AWLT shows a similar mode, but with a narrower adjustment range to balance the handling performance and lateral acceleration. Overall, the control laws of AWLT demonstrate a notable correlation with both velocity and longitudinal acceleration.