Robust fixed-order dynamic output feedback controller design for nonlinear uncertain suspension system

•Robust fixed-order non-fragile dynamic output feedback controller, for suspension systems is proposed.•The most complete model of linear controller with direct feedthrough parameter is considered.•An H∞H∞ performance index is used to attenuate external disturbance caused by road surface.•Norm-bounded perturbations of controller parameters can be tolerated using the proposed method.•Appropriate LMI constraints are considered in order to prevent controller parameters from taking very large and undesirable amounts.

This paper deals with designing a robust fixed-order non-fragile dynamic output feedback controller for active suspension system of a quarter-car, by means of convex optimization and linear matrix inequalities (LMIs). Our purpose is to design a low-order controller that keeps the desired design specifications besides the simplicity of the implementation. The proposed controller is capable of asymptotically stabilizing the closed-loop system and developing H∞H∞ control, despite model uncertainties and nonlinear dynamics of the quarter-car as well as the norm bounded perturbations of controller parameters. Furthermore, controller parameters are prevented from taking very large and undesirable amounts through appropriate LMI constraints. Finally, a numerical example is presented to show the effectiveness of the proposed method by comparing it with similar works.