Design of PAM and PWM digital controllers for cascaded analog systems

摘要

This paper discusses the relationship among various recently developed constant state-feedbackdigital redesign methods. Then, for a unity-output feedback system with an analog plant in cascadewith an analog controller, the best and simple Chebyshev quadrature digital redesign method isutilized to find new pulse-amplitude-modulated (PAM) and pulse-width-modulated (PWM) digitalcontrollers for effective digital control of the analog plant. The digital controllers are determined fromexisting or pre-designed analog controllers as in the case of PID controllers for industrial controlprocesses and robotics, phase lead-lag compensators for servo-mechanisms and regulator systemsand guidance-autopilots for aircraft and missiles etc. The proposed method provides an alternativemethodology for indirect digital design of a continuous-time unity-output feedback system andenables us to accurately and effectively implement an existing or pre-designed cascaded analogcontroller via a digital controller.