North China Electric Power University
Linear active disturbance rejection control (LADRC) has a fixed control structure. Its design is independent of the mathematical model of the controlled system, and its performance is determined by the feedback controller gain and the observer gain, thus it has great application potential in industrial processes. However, because the order of the model of the industrial process is uncertain, the high-frequency gain of the controlled system is hard to obtain, so the tuning of the parameters of LADRC is crucial for the application in process control. Considering that PID controllers are widely used in process control and there are mature PID tuning theories and tuning rules, this paper will investigate the tuning of second-order LADRC based on existing PID tuning rules. This method is based on the first-order process with deadtime (FOPDT) model and utilizes the transformation between PID controller parameters and second-order LADRC parameters. The LADRC tuning rules are functions of the normalized delay of the FOPDT model, and the calculation is quite simple. The proposed method makes it easy for control engineers who have mastered PID tuning methods to derive the corresponding LADRC tuning rules, which will enrich the theory and method of LADRC tuning.