PID tuning with fuzzy set-point weighting

A novel method based on fuzzy logic for the tuning of PID controllers is described. The main idea is to multiply the set-point for the proportional action by a parameter, which is determined in a fuzzy way, depending on the current value of the system error and its derivative. The valves of the proportional gain and the integral and derivative time constants are assigned according to the well-known Ziegler-Nichols formula. Thus, both a good load disturbance attenuation and a good step response can be achieved. Moreover, an auto-tuning procedure for the overall system can be implemented by means of genetic algorithms. Simulation results show the improvements obtained by this approach that can be carried out at the expense of a small extra computational effort and with a simple modification of the typical existing industrial setup