Discrete-time proportional and integral observer and observer-based controller for systems both with unknown input and output disturbances

In this paper, a novel discrete proportional and integral observer is proposed for estimating the system state, input and output disturbances at the same time. Compared with the previous results, the proposed observer has an advantage in handling output disturbances. A simulated numerical example is given to demonstrate the efficiency. By using the estimates of the state and disturbance, an observer-based controller with disturbance accommodation is designed to ensure the system stability and to satisfy the specified performance index. A simulated study of a reduced-order gas turbine discrete model is given to illustrate the design approach, and encouraging simulation results are obtained. Copyright q 2007 John Wiley & Sons, Ltd