PI/PID controller tuning via LQR approach

This paper presents a new optimal PI/PID controller tuning algorithms for l ow-order plus time-delay processes via LQR approach. A new criterion for se lection of the Q and R matrices is proposed which will lead to the desired natural frequency and damping ratio of the closed-loop system. The examples with various dynamics are included to demonstrate the effectiveness of the tuning algorithms and show significant improvement over the existing PID t uning methods. The robustness property of the tuning algorithms is also ana lyzed, and it is shown that the LQR system is robustly stable for the small modeling error. (C) 2000 Elsevier Science Ltd. All rights reserved.