The invention belongs to the field of precision
motion control and
intelligent control algorithms, and relates to a time-varying iterative learning feedforward
control system and method based on
wavelet transform. The
system comprises an addition and subtraction arithmetic unit, a first memory, a time-varying
robust filter Q (f, t) based on
wavelet transform, a learning filter L (z), a first addition arithmetic unit, a second memory, a second addition arithmetic unit, a
feedback controller C (z) and a controlled object P (z). According to the method, trajectory
tracking error signals are repeatedly collected, the coherent power spectrum and the energy contribution distribution of the trajectory
tracking error signals are extracted through
wavelet transform, then a time-varying
robust filter Q (f, t) is constructed, and repetitive error components are accurately extracted. The feed-forward control quantity is iteratively updated based on the repetitive error component, non-repetitive error amplification can be effectively inhibited, and the trajectory tracking precision is remarkably improved. The method is suitable for
servo systems needing high-precision repetitive trajectory tracking, such as a photoetching
machine workpiece table, a precision motion platform and an ultra-precision
machining system.