Model-Free Control for a Vehicle Hydraulic Suspension System

This paper presents a novel model-free control for an active suspension system to achieve vehicle riding and passenger comfort in the presence of road disturbances. Compared with the previous designs، the proposed design does not employ the force control and uses only the position control. As a result، its design is simpler and less computational. The controller is designed for a quarter car active suspension system driven by hydraulic actuator with a nonlinear model. To obtain the proposed controller، the feedback linearization control and estimation of uncertainty and then compensation by time-delay approach are used. Therefore، it can overcome nonlinearity and uncertainty associated with model. It uses feedbacks of displacement، speed and acceleration of sprung mass. A state space model for the hydraulic suspension system is derived and the system stability is proven. Simulation results show the desired performance of the suspension system to achieve the convergence of body to the equilibrium point with an ignorable error. Comparing performance of the active suspension system with the passive suspension system shows the efficiency and superiority of the proposed controller in providing the passenger comfort and ride handling.