Fractional Repetitive Control of Nanopositioning Stages for High-Speed Scanning Using Low-Pass FIR Variable Fractional Delay Filter

The repetitive control (RC), capable of tracking periodic trajectories and rejecting periodic disturbances, is a promising technique to control the nanopositioning stages for high-speed raster scanning. In digital implementation of the RC scheme, the number of delay points has to be an integer, which implies that the sampling frequency should be an integer multiple of the desired tracking frequency. Clearly, this is a severe limitation on the...