Mixed H₂/H_∞ robust output feedback control for uncertain linear systems

The paper deals with the mixed H₂/H_∞ robust output feedback control problem for linear systems subject to norm-bounded parameter uncertainty in both the state and the output matrices of the state-space model. The full-order controllers derived are not only guaranteed to satisfy a pre-specified H_∞ disturbance attenuation level for all admissible parameter uncertainties, but also provide an optimized bound for the worst-case H₂ cost function. The obtained results require the solutions of one parameter-dependent algebraic Riccati equation and three coupled parameter-dependent nonlinear equations. A numerical algorithm for solving these parameter-dependent nonlinear equations is also presented.