• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.975-980
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• 2004

Positioning system is widely used for many practical applications. This system requires a good controller to achieve high accuracy and fast response with simple and self-adjustable design. In order to satisfy the above requirements, a new practical controller for positioning systems, namely nominal characteristic trajectory following (NCTF) controller with PI compensator, has been proposed. However, the effect of actuator saturation can not be completely compensated for integrator windup when the object parameters vary. This paper presents a method to improve the NCTF controller by overcoming the problem of integrator windup by adopting a fuzzy system. The improvement of the NCTF controller is evaluated through simulation using a rotary positioning system. The simulation result has demonstrated the effectiveness of the compensated NCTF in overcoming the problem of integrator windup.

• International Journal of Precision Engineering and Manufacturing
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• 제9권2호
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• pp.44-49
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• 2008

This paper describes the problem of ultraprecision positioning with a ball screw mechanism in the microdynamic range, along with its solution. We compared the characteristics of two ball screw mechanisms with different table masses. The experimental results showed that the vibration resulting from the low stiffness of the ball screw degraded the positioning performance in the microdynamic range for the heavyweight mechanism. The proposed nominal characteristic trajectory following (NCTF) controller was designed for ultra precision positioning of the ball screw mechanism. The basic NCTF control system achieved ultra precision positioning performance with the lightweight mechanism, but not with the heavyweight mechanism. A conditional notch filter was added to the NCTF controller to overcome this problem. Despite the differences in payload and friction, both mechanisms then showed similar positioning performance, demonstrating the high robustness and effectiveness of the improved NCTF controller with the conditional notch filter. The experimental results demonstrated that the improved NCTF control system with the conditional notch filter achieved ultra precision positioning with a positioning accuracy of better than 10 nm, independent of the reference step input height.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.665-666
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• 2008

• 대한기계학회논문집A
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• 제34권11호
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• pp.1613-1622
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• 2010

본 연구는 고진공 환경중 초음파 리니어 스테이지의 나노미터 위치제어를 기술하고 있다. 고진공 환경 중 초정밀 위치 제어 시스템에 응용하기 위해 3 차 종진동 모드와 6 차 횡진동 모드를 가지는 BLT를 개발 했다. 안정적인 고출력을 위해 BLT 는 하나의 공진 주파수로 두 개의 모드 진동을 발생 시켜야 한다. 하나의 공진 주파수를 이용 하기 위해 어드미턴스를 변화시켜 각 모드의 공진 주파수를 일치시켜 조건이 다른 대기 환경에서 안정적인 고출력을 얻을 수 있었다. 기압 변화에 따라 구동 특성이 달라지는 시스템을 제어하기 위해 마찰력 변화에 따른 비선형 특성을 보상한 NCTF 제어를 사용했다. 설계된 제어기를 이용해 고진공 환경에서 시스템을 나노미터 정도로 제어하는 결과를 얻을 수 있었다.