Preview Tracking Control for Discrete-Time Multirate Systems: An Internal Model-Based Approach

This paper investigates the preview tracking problem for discrete-time multirate systems under the scenario of the external signals with amplitude non-attenuation. Since the input and the state cannot be measured at the same time, the multirate system is first lifted into the single-rate system. Noting that the external signals are previewable and their amplitudes are unattenuated, an auxiliary system with preview information and a dynamic compensator with internal model are introduced, respectively. On this basis, the preview tracking problem can be converted to the output regulation problem of an augmented system with the aid of the state augmentation technique. Through verifying the solvability of the output regulation problem, the sufficient conditions and the corresponding controller with preview action and feedforward compensation are presented for the output regulation problem as well as the original problem. Finally, a numeric simulation result is provided to verify the validity of the proposed method.