Observer-Based Model Reference Sliding-Mode Control of Active Suspension Systems

Abstract

In this paper a model reference variable structure controller (VSC) for an active suspension system is designed. A half vehicle model is used in which, the vertical and pitch motions of the mass supported by the suspension and the vertical motion of the suspension masses are considered. Sliding mode controller is applied for the purpose of disturbance attenuation. Unit vector approach, which is a sliding mode control structure for multivariable systems, is used and a robust adaptive nonlinear controller is designed. A reduced-order observer is designed to use only output information. Robust eigenstructure assignment method is implemented in the line of sliding surface design. Simulation results verify the effectiveness of the proposed nonlinear controller scheme in comparison with the passive suspension system and also H∞ technique. The output of the closed-loop system can also smoothly track a set point in a manner that the vertical position of vehicle may be regulated toward the desired point.