Tracking variable periodic signals with variable sampling rate - Frequency domain approach

This paper presents two adaptive control algorithms for tracking repetitive reference signals with dynamic change in period. These two control algorithms are the adaptive feedforward tracking controller and the adaptive feedback repetitive controller. Under the assumption that the controlled plant is linear time invariant and whose steady state behaviour can be described by its frequency response, the proposed algorithms generate the controls based on the estimation of the gain and phase of the plant at selected frequencies contained in the reference signal. Hence, no structural knowledge of the plant needs to be known. It has been shown that the adaptive feedforward tracking controller provides fast transient response, and the adaptive feedback repetitive controller exhibits good steady state performance. The sequential combination of the two algorithms is studied, which demonstrates fast transient as well as good steady state performance. Experimental results are presented to illustrate the effectiveness of the proposed schemes. Copyright (C) 2001 IFAC.