A new method on repetitive tracking control of electro-hydraulic servo systems

A new repetitive tracking control scheme for electrohydraulic servo systems is presented in this paper. For a repetitive task of the system, both input and output signals is approximated by Fourier series(FS) and their functional relationship is expressed by a mapping which is the ratio of their corresponding components in the Fourier space. An iterative algorithm is designed by using a repetitive strategy according to this inverse mapping, output error and input of the last cycle. The experiment results on a plastic injection molding machine show that the proposed controller can improve the performance significantly.