control of active vehicle suspensions with actuator time delay

The paper deals with the H ∞ control problem for active vehicle suspension systems with actuator time delay. The time delay for the actuator is assumed as uncertain time-invariant but has a known constant bound. By suitably formulating the sprung mass acceleration, suspension deflection and tyre deflection as the optimization object and considering the actuator time delay, a delay-dependent memoryless state feedback H ∞ controller is designed in terms of the feasibility of certain delay-dependent matrix inequalities. A quarter-car model with active suspension system is considered in this paper and a numerical example is employed to illustrate the effectiveness of the proposed approach. It is confirmed by the simulations that the designed controller not only can achieve the optimal performance for active suspensions but also preserves the closed-loop stability in spite of the existence of the actuator time delay within allowable bound.