Constrained H∞ control of active suspensions:: An LMI approach

This paper suggests a constrained H(infinity) control scheme for active suspensions with output and control constraints. The W. performance is used to measure ride comfort so that more general road disturbances can be considered. Time-domain constraints, representing requirements for: 1) good road holding which may have an impact on safety; 2) suspension stroke limitation; and 3) avoidance of actuator saturation, are captured using the concept of reachable sets and state-space ellipsoids. The proposed approach can potentially achieve the best possible ride comfort by allowing constrained variables free as long as they remain within given bounds. A state feedback solution to the constrained H(infinity) active suspension control problem is derived in the framework of linear matrix inequality (LMI) optimization and multiobjective control. Analysis and simulation results for a two-degree-of-freedom (2-DOF) quarter-car model show possible improvements on ride comfort, while respecting time-domain hard constraints.