A Fast, Easily Tuned, Siso, Model Predictive Controller

It is commonly believed that for SISO systems, well tuned PID controllers work as well as model-based controllers and that PID controllers are more robust to model errors. In this paper we present a novel offset-free constrained LQ controller for SISO systems, which is implemented in an efficient way so that the total controller execution time is similar to that of a PID. The proposed controller has three modules: a state and disturbance estimator, a target calculation, and a constrained dynamic optimization. It is shown that the proposed controller outperforms PID both in setpoint changes and disturbance rejection, it is robust to model errors, it is insensitive to measurement noise, it handles constraints much better than common anti-windup PID. Tuning the proposed controller is simple. In principle, there are three tuning parameters to choose, but in all examples presented only one was actually varied, obtaining a clear and intuitive effect on the closed-loop performance. Copyright c © 2004 IFAC.