Actuator fault estimation for two-stage chemical reactor system based on delta operator approach

Based on the delta operator approach, a new method of actuator fault estimation for a two-stage chemical reactor system is presented with time-delay and outside disturbances. Firstly, a nonlinear delta operator mathematical model is established to describe the two-stage chemical reactor systems by using the mechanism analysis method. In order to estimate the actuator fault, the proportional–integral observer (PIO) is employed as the state estimator. Meanwhile, a novel delta operator-based actuator fault estimation algorithm is proposed. Then, by means of the Lyapunov–Krasovskii functional technique, sufficient conditions are derived to guarantee that the error system is asymptotically stable with a predefined H ∞ performance index. Next, the desired PIO can be designed. Finally, simulation results are given to illustrate the effectiveness of the proposed methods.