Generalized digital redesign method by N-delay control and its application to motion control

A new digital redesign method is proposed for feedback control systems, by which the states in the continuous-time system are completely reserved in the redesigned sampled-data system. The features of the proposed method are: (1) the N-delay control is employed, and the lth plant input is changed N_l times during one sampling period; (2) the states of the redesigned sampled-data system completely match those of the original continuous-time closed-loop system at every sampling period; and (3) the proposed redesign method can be applicable for a state-feedback and/or a dynamic controller. An illustrative example of position control using a DC servo motor is presented. The advantages of the proposed redesign approach are demonstrated both in the time and frequency domains