Tracking variable periodic signals with fixed sampling rate - feedforward control

Recent research has shown that the feedback repetitive control is very efficient in tracking periodic signals. However, the existing repetitive control algorithms require an integer number of samples in each period. In some industry applications where the signal period varies but other requirements on the data acquisition system force a fixed sample rate, the number of samples per period may be a non-integer. To address this problem, adaptive feedback repetitive controllers have been proposed. Although the adaptive feedback repetitive control provides good steady state performance, the transient response is not fast. This paper presents a new adaptive feedforward control with fixed sampling rate to track periodic signals with variations in periods. The experimental result on a servomotor demonstrates that the proposed feedforward tracking controller has fast transient response.