Vehicle stability control of 4WD electric vehicle using combined adaptive sliding mode controller and control allocation method

Vehicle stability control is one of control strategy to improve yaw stability of the 4 wheel drive electric vehicle (4WD EV). The main purpose of this control strategy is to enhance the vehicle handling and stability such that satisfy the occupant safety even though in the critical condition. The control strategy consists of multi layer control loops. The upper control loop, which employs adaptive sliding mode control, is responsible to specify control effectors required for keeping 4WD EV yaw stability. Moreover, the lower control loop, which is responsible to determine actual control to every actuator, is employed dynamic control allocation. By using this proposed configuration, the control performance is improved, since the upper control loop is developed with an adaptation tuning approach and can deal with unknown but bounded system uncertainties. The proposed method have been successfully proved by using Lyapunov theory to ensure its stability. The simulation results show that the proposed strategy can improve the handling stability of 4WD EV, even though it drives in various conditions.