Sliding Mode Control for Vibration Comfort Improvement of a 7-DOF Nonlinear Active Vehicle Suspension Model

Owing to the presence of nonlinear elements of a vehicle, when the vehicle goes through a rough-road-surface, such as consecutive speed control humps (SCHs), unexpected vibrations will exist in vehicle suspension systems, such as chaos, bifurcation, and quasi-periodic so on. In this paper, we first study the possibility of chaotic vibration of the seven degree-of-freedom (7-DOF) full vehicle model under consecutive SCHs on the highway. Then, a non-chattering sliding mode control method is proposed. The effectiveness of the sliding mode control method for the nonlinear vibration control of the vehicle suspension model is verified by numerical simulation. By comparing the changes in the vibration amplitude of the vehicle in the same velocity region before and after the control, we determine whether the ride comfort is improved. The results show that not only is the system’s chaos vibration effectively controlled, but also the ride comfort is significantly improved. The results can be applied in the design of a vehicle and in pavement of road humps.