Novel Direct Yaw Moment Control of Multi-Wheel Hub Motor Driven Vehicles for Improving Mobility and Stability

This paper proposes a novel direct yaw moment control algorithm for improving the mobility and stability of eight-wheel independently drive (8WID) electric vehicles (EVs) in steering condition. This algorithm adopts a hierarchical structure consisting of an upper layer and a lower layer. Firstly, a modified desired yaw rate is proposed, which is obtained by a two-degree-of-freedom (2DOF) vehicle dynamic model and adjusted by different working conditions, as the control target of the upper controller. After that, the fuzzy PI control is adopted here to optimize the PI parameters in real-time. The fuzzy rules is determined by the sideslip angle and yaw rate error. The lower layer is functionalized to realize the anti-slip control, which observes the total disturbance of the wheel system by extended state observer (ESO) and utilizes two sliding mode controllers by applying the backstepping method. Meanwhile, the consistent coaxial method is applied to keep the torque adjustment of coaxial motors equal to maintain the yaw moment unchanged. Finally, the proposed control strategy is validated through hardware-in-loop real-time simulation and a prototyped vehicle test. The results illustrate that the proposed algorithm effectively improves vehicle mobility and stability.