Mixed H2/H∞ robust controller design based LMI techniques

H2 and H∞ optimal control are two important breakthroughs in modern robust control. In recent years, the H2 and H∞ controller design techniques have gained a lot of research attention. Both have strong theoretical basis and are efficient algorithms for synthesizing optimal controllers. The performance of H2 robust controller is useful to handle stochastic aspects such as measurement noise and capture the control cost. In the robust H2 approach, the controller is designed to minimize an upper bound on the worst case H2 norm for a range of admissible plant perturbations. When a model under analysis is applied with H2 robust controller, the closed loop system will have a good dynamic system performance, but it has poor robustness for the external disturbances of the uncertain system model. The performance of H∞ is convenient to enforce robustness to model uncertainty, but it is based on compromising system performance. Their combination, the mixed H2/H∞ allows intuitive quadratic performance specifications of the H2 synthesis with robust stability requirements specifications expressed by the H∞ synthesis. In time domain aspects, satisfactory time response and closed loop damping can often be achieved by enforcing the closed loop poles into a predetermined region of the left half plane. Combining these requirements to form so-called mixed H2/H∞ design with regional pole placement constraints allows for more flexible and accurate specification of closed-loop behavior. This chapter introduces the work of design of improved LMI-based robust output feedback controller and related simulations. © Springer-Verlag Berlin Heidelberg 2014.