A new approach to optimum active vehicle suspensions using delayed feedback

摘要

A new approach to optimal control of vehicle suspension systems is proposed. The feedback control law is simple time-delayed relative accelerations of the sprung and unsprung masses. The critical feature of the proposed technique is the utilization of a controlled time delay in the feedback loop, which is traditionally looked upon as an undesirable element in the dynamic controls. The objective here is to properly select the feedback gain and time delay such that the mean square acceleration response (MSAR) of the sprung mass is minimized, over a wide band freqency range when subjected to certain constraints. The constraints are dictated by the vehicle stability characteristics and the physical bounds placed on the control parameters. Feasibility of the proposed methodology is demonstrated using a Simple Quarter Car (SQC) model, and the constrained optimization is carried out in the frequency domain with the road irregularities described as random processes. The challenge lies in the implementation of the proposed method for realistic cases where suspension systems are much more complex (full car model, for instance) and the controllability of parameters are limited. The novelty of the method is in two fronts: a) the control feedback is simple relative delayed acceleration of the sprung and unsprung masses, b) the vibration suppression of the sprung mass is done optimally, which makes it effective for a wide band excitation frequency range.