Robust nonfragile H∞ optimum control for active suspension systems with time-varying actuator delay

The active suspension has drawn considerable attention due to its superiority in improving the vehicle vertical dynamics. This paper investigates robust nonfragile H-infinity optimal control for the vehicle active suspension with time-varying actuator delay. Firstly, the dynamic equation of an active suspension system with actuator delay is established in terms of the main performance objectives, that is, ride comfort, handling ability, and road holding. Then, a robust nonfragile H-infinity optimal controller is proposed to deal with the problem of active suspension control with time delay and actuator uncertainty, which is based on Lyapunov theory, convex optimization, and the linear matrix inequality approach. Finally, a quarter-car test rig is used for an experiment to illustrate the effectiveness of the proposed controller. Simulation and experimental results demonstrate that the proposed controller can ensure the asymptotic stability of the closed-loop system with bounded time-varying actuator delay, while managing the tradeoff between the conflicting performances and achieving performance optimization for the active suspension.