Design of mixed H_2/H_∞ controller

In state space descriptions, four typical systems of mixed H-two/H-infinity control were defined. They are full information system, full control system, feedforward disturbance system and output estimation system. Their controllers were designed to optimize the performance based on a kind of quadratic stable. Mixed H-two/H-infinity control system was decomposed into an inner matrix and a mixed H-two/H-infinity output estimation system. The output feedback controller was deduced according to this decomposition. Mixed H-two/H-infinity controller delivered here are analog to H-two and H-infinity controller in that they have the same controller structure, the same number of Riccati equations and similar Riccati equations. The given controllers including the H-two and H-infinity cases, can be treated as unified controllers of H-two, H-infinity and mixed H-two/H-infinity control. Finally, a simple example was given to illustrate the proposed methods.