Multirate repetitive control for an industrial print-belt system

The increasing complexity of next-generation mechatronic systems leads to different types of periodic disturbances, which require dedicated repetitive control strategies to attenuate. The aim of this paper is to develop a new repetitive control strategy to completely attenuate a periodic disturbance and a user-defined number of relevant higher harmonics with limited memory usage. To this end, a multirate repetitive controller is developed, which combines a buffer at a reduced sampling rate with learning and robustness filters at the original sampling rate of the system. This leads to a linear periodic time-varying system, for which convergence conditions are developed. The method is implemented on an industrial print-belt system, demonstrating that it can match the performance of traditional repetitive control while significantly reducing the memory usage.