Mixed-norm H2/L1 controller synthesis via fixed-order dynamic compensation: a Riccati equation approach

One of the fundamental problems in feedback control design is the ability of the control system to reject uncertain exogenous disturbances. Since a single performance objective is seldom adequate to capture multiple and often conflicting system disturbances, in this paper we develop a Riccati equation approach for mixed H₂/L ₁ controller synthesis via fixed-order dynamic compensation. This multiobjective problem is treated by forming a convex combination of both the H₂ (quadratic) and L₁ (worst-case peak amplitude response) performance measures. For flexibility in controller synthesis, we adopt the approach of fixed-structure controller design which allows consideration of arbitrary controller structures, including order, internal structure, and decentralization