Investigation of Adaptive Control Approaches for Vehicle Active Suspension Systems

A nonlinear Self-Tuning Control (STC) scheme for the nonlinear vehicle active suspension system is investigated and analyzed as an alternative suspension control methodology. The result of the nonlinear STC approach is compared with the linear STC and the model reference adaptive control (MRAC) schemes. The objective of these adaptive control active suspension systems (ACASS) is to tune the controller of the active suspension system automatically such that vehicle disturbance and vibration are reduced to a prespecified level determined by an "ideal" conceptual suspension system. Thus, an ACASS can accommodate for variances in sprung load and suspension component characteristics. The design and performance analysis of a nonlinear STC suspension system is based on a quarter-car model. Our results show significant improvement in the road handling performance of a high-speed vehicle with the STC active suspension system.