Modified PID controller based on H∞ theory

A simple design procedure for the auto-tuning of PID controllers is developed in this paper based on the modern H_∞ control theory. Straightforward analytical formulas are given for the PID controller parameters. They have the advantage to take into account both robustness aspects and desired closed loop characteristics. The design method can be easily combined with existing process identification techniques to implement an auto-tuning PID controller. Simulation studies are given to compare this design method to the Ziegler-Nichols method. The results show that the new method provides much faster and smoother responses, which generally are more desirable in the process control setting