Direct yaw moment-based vehicle stability control system for eight-wheeled vehicles

This paper presents a vehicle stability control system using a direct yaw moment control for a vehicle with an eight-wheeled independent driving/braking and a four-wheeled steering system. The controller was designed based on a hierarchical control structure comprised of upper- and lower-layer controllers. Two single-input fuzzy logic controllers were employed in the upper-layer controller to determine the desired direct yaw moment based on the errors between the desired and actual yaw rates and sideslip angles. A desired vehicle model was used to compute the desired sideslip angle and yaw rate. To distribute the desired direct yaw moment, an optimal tyre force distribution technique, known as a two-stage weighted square sum minimisation (WSSM) of tyre workload, was employed in the lower layer to ensure the efficient allocation of longitudinal tyre forces while minimising the tyre workload. Matlab/Simulink simulations were conducted to assess the performance of the control system in maintaining vehicle stability during step-steer and braking-in-turn manoeuvres. The simulation results demonstrated that the two-stage WSSM of tyre workload outperformed the ordinary WSSM of tyre workload and achieved smaller root mean square errors for yaw rate and sideslip angle and a lower maximum tyre workload.