Automatic tuning of two-degree-of-freedom control for d.c. servo motor systems

Abstract

In this paper, we present the first application of the relay feedback approach to the automatic tuning of a two-degree-of-freedom (2-DOF) controller to achieve robust motion control for d.c. servo motor systems. The only specifications required from the user are simple and classical parameters for the desired closed-loop transfer function and an appropriate sensitivity function determining the robustness of the closed-loop system. Heuristics are provided for the selection of key parameters of these functions. Two variations of the conventional relay feedback methods were proposed and investigated. Both of these variations introduce an appropriate phase angle in the negative inverse describing function of the relay to excite a sustained limit cycle oscillation. Simulation and experimental results from a voltage controllable d.c. motor system illustrate the effectiveness of the proposed methods.