A QFT approach to robust dual-rate control systems

Abstract: A dual-rate control system is a hybrid system composed of continuous-time and discrete-time elements with two sampling frequencies. In this work, a new frequency domain analysis and design approach, based on the Quantitative Feedback Theory (QFT) is developed, to cope with robust stability and tracking specifications. Tracking specifications are considered not only in the discrete-time but also in continuous-time, that allow a precise description of the intersample behavior (ripples), and characterization of frequencies below and beyond the Nyquist frequency. Several illustrative examples and a case study has been developed.