DESIGN OF AN ACTIVE 4WS SYSTEM WITH PHYSICAL UNCERTAINTIES

In this paper a new approach to the design of an active four-wheel-ste ered (4WS) control system is introduced. The problems of the conventio nally used LQ-controller-based virtual model following control strateg ies are analyzed, and several problems are addressed. Two main problem s of the LQ controller are highlighted: the external disturbance rejec tion, and the robustness of the controlled system in the face of param etric uncertainties. In the paper a combined Robust Linear Quadratic R egulator (RLQR) and H-infinity controller design is presented for an a ctive 4WS vehicle. The applicability of this kind of controllers is pr oven in this particular design case.