A chain scattering-matrix description approach to H∞ control

Chain scattering-matrix descriptions and J-lossless coprime factorizations are employed to develop a relatively simple method for the synthesis of the continuous-time H^∞ suboptimal control. Analogously to the Youla parameterization of all stabilizing controllers, the authors derive an identity to generate all suboptimal controllers. The derivation is carried out in terms of transfer function matrices although the final formulas are in state space. The approach provides a clear connection at the transfer function level between coprime factorizations and algebraic Riccati equations that are associated with the solutions of the problem