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

A novel discrete proportional-integral observer is proposed to estimate system states, input and output disturbances simultaneously. In contrast to 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 satisfy the guaranteed cost control 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.