Robust linear control of an active suspension on a quarter car test-rig

This paper presents the design of a robust linear controller for an active suspension mounted in a quarter car test-rig. Unlike most active suspension control design methods, the presented approach does not require a (nonlinear) physical model of either the car or the shock-absorber, which are very time consuming to derive. The presented method is based on linear techniques well supported by CACSD-software tools, yielding a fast control design approach, applicable to almost any active suspension system. Linear black box models are identified using frequency domain identification techniques, while robust linear control design techniques (H∞ and μ-synthesis) account for the model uncertainties introduced by the linear model approximation of the nonlinear dynamics. Although this linear approach introduces some conservatism, it is shown that the desired performance is achieved in simulation as well as on the experimental test-rig.