Lyapunov-based Design of a Model Reference Adaptive Control for Half-Car Active Suspension Systems

Abstract

This paper proposes a model reference adaptive control (MRAC) design for vehicle active suspension systems with unknown spring stiffness and damping coefficients with the aim of improving the performance of suspension systems. A mathematical model of a half-car active suspension system is first presented, then a reference model of a half-car suspension system that utilizes the skyhook damping concept is proposed. The control law and adaptation laws for the MRAC that guarantee the dynamic responses of the active suspension system follow well the dynamic responses of the reference model, were derived based on the Lyapunov stability criteria. To evaluate the advantages of the proposed reference model as well as the efficiency of the designed MRAC, the dynamic responses of the reference model, passive, and active suspension systems were analyzed and evaluated both in the frequency and time domains. The obtained results demonstrated that the active suspension system with MRAC provides better performance in terms of ride comfort and suspension deflection compared with the passive suspension system