Quantized Controller Design Using Feedback Modulators

This paper deals with discrete-valued controller design for linear systems considering its limitations on temporal and spatial resolutions. First, we introduce a feedback modulator (FBM), which converts continuous-valued control input to discrete-valued one. It is composed of a feedback connection of sampler, holder, quantizer and a stable filter as a tunable parameter. Then it is combined with a continuous-valued compensator appropriately designed in advance. Based on the analysis of performance and stability issues for the FBM and FBM-based control systems, we provide a sufficient condition for the tunable filter to stabilize the whole system, in terms of relation between its time constant and the temporal resolution. This condition gives as an easy-to-follow guide to design a practical FBM. Effectiveness of the proposed method is validated with numerical simulations, with comparison to conventional approaches.