An adaptive I-PD controller based on frequency domain system identification

This paper presents an approach to auto-tune an I-PD controller for plants with long time delays such as pneumatic cylinders. The proposed control scheme estimates the frequency response of a plant using the sliding discrete Fourier transform (DFT) and employs a modified Smith predictor to reduce the effect of time delay. Controller gains are determined so as to minimize the error between the open-loop frequency response of the reference model and that of the actual system.