Two-Degree-of-Freedom Control of Non-minimum Phase Mechanical System

Abstract

This paper proposes Two-degree-of-freedom control of Non-minimum phase (NMP) system. One of the essential tasks for controlling the plant is to follow the desired trajectory. Exact matching of set point and actual output can be possible if inverse transfer function model of the system is connected in cascade with the original one. But it is true, only for minimum phase system; whereas inverse model connected NMP system always produce unbounded output response. Here, a novel technique has been proposed, where inverse model NMP is controlled by Model Reference Adaptive Control (MRAC) as feed-forward compensation and arbitrary pole placement technique for original transfer function model has been used as feedback controller in Two-degree-of-freedom (2DOF) framework. The satisfactory result of 2DOF controlled practical NMP system has been studied in a simulation environment and compared it with the Proportional Integral Derivative (PID) and State feedback control method.