On-line autotuning of PID controller for desired closed-loop response

This paper presents a concept of a PID controller tuning that employs feedback relay method. The identification test is conducted on-line in an additional loop. The presented method allows a frequent adaptation of the controller settings to the changing operating conditions of the system without losing the control of the process. The article includes the results of simulations for both types of adaptation carried out during the control over the same plant.