PID gain tuning for Robust Control of PMDC Motor with tracking and disturbance rejection through H∞

Abstract

Permanent-magnet (PM) motors are employed in numerous industrial control applications for their high efficiency, simple mechanism and low cost. In most of the applications, either the plant model is inaccurately defined or the plant parameters are prone to variations over period of time. Also, in most of the applications, have a requirement of good tracking as well as good disturbance rejection, two competing requirements. The controller should cater to the parameter variations as well as provide robust performance against external disturbances and hence requires a robust control approach towards designing a controller. A classical PID controller, which lacks robustness requirements is augmented by H∞ optimization based gain tuning to meet the robustness requirements. This paper discusses a PID controller design using H∞ optimization approach. Different performance goals for tracking and disturbance rejection are defined and PID gains are tuned to meet the goals in H∞ sense. A commercial Maxon RE35 motor is selected for modeling and simulation.