초정밀 작업용 테이블의 진동억제 시스템 설계에 관한 연구

Abstract

This paper aims to establish a micro-vibration suppression system for a workbench where high-precision semiconductor manufacturing equipment is placed and operated. In other words, the main purpose of the study is to solve an issue of equipment not performing at its full capability due to effects such as disturbance. Vibration suppression capability determines work performance (precision) in high-precision work. Huge technological advancements have been made owing to the introduction of active vibration control techniques, overcoming the limitations of passive vibration suppression technology. But a lot of research to improve the performance of equipment is still in progress. Currently, much interest is given to improve the performance of equipment by developing and applying new actuators. And such a trend shows a tendency of pursuing technological advancement in a hardware sector and relatively, not much effort is put into a theoretical sector. Although it is recognized that a high level of performance improvement cannot be achieved without introducing an appropriate suppression technology, it is not easy to try it due to various challenges. From the control technological perspective, the most challenging but must-be-solved issue is mutual interference between input and output, which makes it difficult to improve performance. As the effect on one input appears simultaneously on several outputs, it is hard to achieve the required vibration suppression performance. For these reasons, this paper suggests a new control technique to clearly understand and solve issues in active control technology. And a method for designing a disturbance suppression system based on the noninteracting control theory is considered. The key point of the noninteracting control theory is to reconfigure the system so that each control input affects only corresponding control output. In other words, several separate and independent systems are simply combined and consist a structure without interference between them. Using this characteristic, it is possible to construct the entire control system by combining individual systems whose controllers are independently designed. In order to efficiently obtain the complex controller gain, the design problem of the noninteracting controller was turned into the problem of finding the optimal solution using the linear matrix inequality (LMI) technique, which is one of the numerical control system design techniques. Despite of the various confinement conditions, a method to obtain the optimal solution efficiently under the given conditions is suggested. In addition, a new control method is presented, which can effectively suppress direct disturbance from the movement of equipment other than disturbance from the floor. Until now, little interest has been given to the research of suppressing device disturbance, and consequently, no clear theoretical or technical results have been drawn. Suppressing the disturbance from the device is a very important issue and a theoretical and technical solution to this matter would enable the work requiring high precision. And it is expected to see the results beyond the technological limitations when using the floor disturbance suppression. Hence, this study presents a new control method which can achieve disturbance suppression performance under more general conditions based on the results of existing research. Based on the fact that disturbances are generally irregular and difficult to clearly understand, this new control method is suggested which can effectively suppress general disturbances caused by movement of equipment without placing any restrictions on the pattern of device movement. Consequently, this paper provides a new design method of the control system to suppress disturbance from the floor and the movement of equipment. Based on the fact that disturbance is irregular and unpredictable, the controller was designed. And the validity of the control technique was evaluated and confirmed through a simulation. And it has been proven through a simulation that this control technique can effectively respond to the disturbances from the floor and the movement of equipment or from the both at the same time. The validity of the controller design method presented in this paper will be confirmed through a field test after making an experimental device.