Robust adaptive PI controllers for large dead-time processes with sensitivity specification

This paper presents a new technique of adaptive PI controller for large dead-time processes with sensitivity specification. On the basis of process input and output data of normal operation in the control loop, the important frequency responses of process are estimated with signal decomposition and Laplace analysis, and then a first-order plus dead-time model is identified for large dead-time processes. Finally PI control parameters are calculated to satisfy sensitivity specification. The adaptive procedure of PI controller does not need any prior knowledge of the process and previous controller while the control loop is still in the normal operation. Simulation examples are given to show both effectiveness and feasibility of the adaptive PI controller.