The active suspension has drawn considerable attention due to its superiority in improving the vehicle vertical dynamics. This paper investigates robust nonfragile H∞ 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∞ 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.

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The vehicle active suspension has drawn considerable attention due to its superiority in improving the vehicle dynamic performance. This paper investigates the nonfragile H∞ control of delayed vehicle active suspension in a finite frequency range under nonstationary running. The control objective is to improve ride quality in a finite frequency band and ensure suspension constraints, and a quarter car model of the active suspension is established for a controller design. Then, the input delay, actuator uncertainty, and external disturbances are considered in the controller design. Moreover, a further generalization of the strict S-procedure is utilized to derive a sufficient condition in terms of linear matrix inequality (LMI) to capture performance in the concerned frequency range. Furthermore, a multi-objective controller is designed based on projection lemma in the framework of the solution of LMIs. A nonstationary road profile is established, and numerical simulations are also conducted to show the effectiveness and robustness of the proposed controller. Finally, experimental tests on a quarter-car test rig are implemented to examine the performance of the proposed controller for real applications.

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