Output feedback constrained H∞ control of active vehicle suspensions

This paper develops an LMI-based solution for output-feedback constrained H_∞ control design, and considers it for active vehicle suspension system. A quarter car model, which captures many features of real structures, is used in this study. To take more general road disturbances than white noise into account in the design procedure, H_∞ performance measure is used to judge ride comfort, ride safety and control effort. To care for time domain constraints, pertaining to suspension working space limitations, the concept of reachable sets and state space ellipsoids is utilized. LMI formulation of the problem makes it possible to ensure desired transient response by imposing appropriate pole location constraints. Numerical simulations have been carried out to compare the designed controller with a state feedback constrained one.