Experimental Results on Nonlinear Position Control of Linear Slider Using Operator-Based Double-Coprime Factorization

Abstract

Disturbance suppression is one of the most important problems in the field of control. Disturbances are external factors that affect the state of the system, such as friction and gravity in dynamical systems. They have unexpected effects on the system response, and in the worst case, they cause the system to become unstable. Disturbance observers exist as controllers to suppress such disturbances. However, disturbance observers treat all disturbances that affect the system as input disturbances, which is not strictly true for nonlinear systems. Therefore, we propose a controller that directly considers disturbances to the internal state of the system and suppresses them more rigorously by using left-coprime factorization based on operator theory. Furthermore, we propose a control system that simultaneously performs target value tracking and disturbance suppression with a single controller by combining this theory with an existing control system using right-coprime factorization and double-coprime factorization. Simulation and actual experiments on a linear motor have confirmed that the designed control system has the two performance features of target value tracking by the existing right-coprime factorization and disturbance suppression by the proposed left-coprime factorization.