A Comparison of IMP-based and DOB-based Controllers for a DC Motor Position Control System

Robust controller design against time-varying disturbance is one of the most important issues in control system design and analysis. Internal Model Principle-based controller design techniques achieve the robust control performance as the controller includes a dynamic model of reference and disturbance. Disturbance Observer-based controllers designed based on extended system models, including disturbance dynamic characteristics, rely primarily on disturbance estimation to provide the same robustness. However, there are not many studies on the similarity of these two control techniques. This paper extends a previous result on the similarity of the two controllers for speed control system to more general position control systems. An extended analytical study is performed to obtain the equivalent property between the two classes of controllers for general higher-order systems. Based on the derived condition, DOB-based controllers can be designed to show the same performance as IMP-based controllers. Position control simulations are included to validate the equivalent performance between the controllers.