Modeling and Control of Cone-Shaped Active Magnetic Bearing System

A magnetically suspended robot joint is developed, which is free of dust and oil generation. Two radial bearings consisting of cone-shaped magnet cores control the rotor motion in the axial and radial directions. A linearized dynamic model is developed for active control of the magnetic bearing system. The control algorithm is constructed such that the axial displacement of the joint is controlled by radial control current to the pairs of facing radial bearings. The stability and control performance is tested through numerical simulation based on the nonlinear model. Experiments are also performed to verify the theoretical development

Robust Design and Tolerancing for the Performance Improvement of Stabilized Mirror System under Vehicle Vibration

In this paper, the robust design and tolerancing of the stabilized mirror is performed to increase its stabilization performance under vehicle vibration. Based on the sensitivity analysis, the seven important control factors are first identified, and then the optimal as well as robust values in the sense of Taguchi method are obtained. Finally, the tolerances associated with each design variables are determined based on a successive sensitivity analysis of the simulated system response so that the deviation in the response from the target value meets the specification requirements. The proposed tolerancing method features that it is a robust but conservative design method and that the computational effort is much less than the Monte Carlo simulation method

원추형 자기 베어링 지지 무마찰 구동장치의 동적해석 및 강인 위치제어

학위논문(박사) - 한국과학기술원 : 기계공학과, 1997.2, [ xiii, 141 p. ]Active magnetic bearings(AMBs) have nowadays been widely adopted in machines and robots, which are operated under the clean room and vacuum chamber environment. Particularly in semiconductor industry, the environment must be ultra-clean to prevent samples from contamination during handling and processing. AMBs can apply a force without mechanical contact and simultaneously do not introduce any mechanical constrains on the controlled object. In addition, they have advantages such as active position control of the suspended part, control of force and stiffness of the handling point, and load sensing capability. The cone-shaped AMBs are very useful as a positioning device because it has a simple structure compared with the conventional AMB and it can achieve the five d.o.f. motion control of a moving part using only four cone-shaped magnet pairs. Separation of the controllers for stabilizing and tracking is very effective for an inherently unstable system like AMBs. The stabilizing controller is to ensure the stability of the closed loop system and the incorporated tracking controller enables the exact tracking of the command input despite of the uncertainties. An outer tracking loop is used to track the command input so that the system performance is not seriously affected. The stabilizing and tracking controllers of AMBs usually use the optimal controller with integral action. However, since such an AMB system often has unknown, nonlinear, or time-varying parameters during operation, a good tracking performance is not likely to be achieved when we rely on a simple linear controller. In order to attain a desired performance for the system with some uncertainty, a linear controller normally requires re-tuning of the controller gains, otherwise a robust control law should be adopted. In this work, a frictionless positioning device suspended by cone-shaped AMBs is developed in the laboratory, which is driven by a brushless DC motor equipped with a resolver. The de...한국과학기술원 : 기계공학과

Fabrication apparatus of anti-biofouling amphiphilic pattern and method thereof

양 친매성 하이브리드 코팅 패턴 제작 장치 및 방법에 관한 것으로, 원통형 실린더, 상기 원통형 실린더 내에 내장된 광원, 상기 원통형 실린더의 외부 표면에 패턴층이 마련된 마스크, 상기 마스크에 의해 형성 된 기판상의 패턴을 처리하는 처리 유닛을 포함하는 구성을 마련하여, 방오 효과를 극대화시킬 수 있다