An integrated algorithm for vehicle stability improvement with the coordination of direct yaw moment and four-wheel steering control

This paper presents an integrated algorithm for enhancing vehicle stability with the coordination of four-wheel steering and direct yaw moment control based on a hierarchical control structure. At the upper level of the integrated control system, the desired four-wheel steering angles and yaw moment are derived using a sliding mode control technique; at the lower level, the control inputs are optimised and implemented using a pseudo-inverse method. A 2 degrees of freedom (DOF) vehicle model is generated to design the integrated control algorithm, and an 8-DOF non-linear vehicle model is developed for numerical simulations. The algorithm is evaluated using a hardware-in-the-loop real-time simulation system (HILS) with the physical implementation of active four-wheel steering and differential braking. It is demonstrated that the proposed algorithm can enhance vehicle handling and stability under different operating conditions.