Static Output Feedback Control for Electrohydraulic Active Suspensions via T–S Fuzzy Model Approach

The paper presents a fuzzy static output feedback controller design approach for vehicle electrohydraulic active suspensions based on Takagi–Sugeno (T–S) fuzzy modeling technique. The T–S fuzzy model is first applied to represent the nonlinear dynamics of an electrohydraulic suspension. Then, the fuzzy static output feedback controller is designed for the obtained T–S fuzzy model to optimize the $H∞$ performance of ride comfort through the parallel distributed compensation scheme. The sufficient conditions for the existence of such a controller are derived in terms of linear matrix inequalities (LMIs) with an equality constraint. A computational algorithm is presented to convert the equality constraint into a LMI so that the controller gains can be obtained by solving a minimization problem with LMI constraints. To validate the effectiveness of the proposed approach, two kinds of static output feedback controllers, which use suspension deflection and sprung mass velocity, and suspension deflection only, respectively, as feedback signals, are designed. It is confirmed by the simulations that the designed controllers can achieve good suspension performance similar to that of the active suspension with optimal skyhook damper.