Abstract:

It is a common phenomenon that time delay frequently happens in preview control systems, so a delay-dependent finite frequency linear parameter-dependent (LPV) controller design approach to solve the problem of preview control for vehicle active suspension systems with input delay and time-varying velocity is proposed. In the controller design, the Padé approach is used to approximate the preview information so as to rewrite it in state-space form. The time-varying velocity is described by a polytope with finite vertices. The existence of admissible controllers is derived in terms of linear matrix inequalities (LMIs). Meantime, different from the existing entire frequencyH_∞ control methods, as the human’s organ is sensitive to the vibration within 4-8 Hz, theH_∞ norm of the car body acceleration is used as the performance optimization index to make it acquire the optimum energy gain attenuation within the concerned frequency band, and the time-domain constraint conditions are also guaranteed. Simulation and experimental results have shown that the proposed controller design approach can yield much less conservative results even actuator delay occur, the proposed approach can achieve better ride comfort when compared with previous approaches.

Key words: finite frequency, H∞ control, look-ahead preview, time-varying delay, vehicle active suspensions