Fuzzy logic control of vehicle suspension systems

Passenger ride comfort has been one of the major issues of vehicle design. The most efficient way of achieving better ride quality is to improve the control of vehicle suspension systems. This paper focuses on developing a robust control algorithm for vehicle suspension systems which can handle a wide range of road roughness as well as mechanical variances of suspension systems while providing a comfort ride. Specifically, a model reference self–tuning fuzzy logic control scheme which consists of a primary and a secondary controller is proposed. The primary controller performs the major control function of the actual sprung mass acceleration. The secondary controller, however, is used to tune the output membership function of the primary fuzzy logic controller on line such that it is capable of adapting process variations such as sprung mass change, spring and damper rate variations and harsh road conditions. The simulation results show that the proposed fuzzy logic controller can make the active suspension system accommodate normal road condition variations and provide near–zero sprung mass acceleration, which in turn yields good quality ride. The comparison study through simulation also demonstrates the superior robustness of the proposed controller over the conventional controller for active vehicle suspension systems.