피드백 선형화 제어기와 외란 관측기를 사용한 유압 서보 실린더 위치제어

Abstract

This paper suggests a hydraulic servo system with a linear controller using feedback linearization. Feedback linearization technique is applied to overcome the non-linearities of the system. The authors pay attention to simpler realization of the controller for the object system and prepare a controller with an additional compensator to recover the response time delay due to using the reduced order model. The control object consists of a hydraulic servo-valve, a servo-cylinder with an inertia load. The control performances of the control system with the newly suggested controllers and a conventional controller (designed based on a system model linearized around a specific operation point) are compared, and the excellency of the controllers proposed in this study is confirmed. And other suggested controller consists of two control part, the one is 「FL-SFC 」for the position control of the hydraulic servo cylinder and the other is disturbance observer for taking into account the effects of the model uncertainties and non-linearities of the system. In this study, a feedback linearization technique was applied to a hydraulic servo system, several controllers suggested in this study and a conventional state feedback controller were implemented to the object hydraulic system. Control performances from the control systems with different controllers were investigated through experiments and simulations. The results of the study are summarized as follows. A mathematical model reduced to a third-order system for a hydraulic servo-system (a cylinder position control system) was derived based on a feedback linearization technique. And the control system with 「FL-SFC」 showed excellent control performances with almost zero delay time and no overshoot under stepwise input responses. Although the representative poles of the state feedback controllers are set to be the same values both in 「C-SFC」 and in 「FL-SFC」, the response time delay and rise time(0→90% response time delay) were significantly shortened in the case of 「FL-SFC」 compared to the case of 「C-SFC」. It was confirmed through experiments that the 「VDC-FL-SFC」 suggested in this study could effectively compensate valve response time delay, and the 「FL-SFC」 could be easily expanded to 「VDC-FL-SFC」 with a minor change in the controller structure. Finally it was shown that the 「FL-SFC-DOB」 was more effective compared with 「FL-SFC」, especially in case that the system has the steady state errors. And also the influences of the disturbances to the object hydraulic system were perfectly removed.