• 한국소음진동공학회논문집
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• 제18권10호
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• pp.997-1005
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• 2008

Linear motor stage is a useful device in precision engineering field because of its simple power transmission mechanism and accurate positioning. Even though linear motor stage shows fine positioning accuracy along travel axis, geometric dependent errors which relay on machining and assembling accuracy should be addressed to increase total positioning performances. In this paper, we suggests a cost effective yaw error compensation servo-system which is mounted on platform of the stage and nullify travel position dependent yaw error. This paper also provides a method of designing a sliding mode control which is robust to existing friction disturbance and model uncertainties. The reachability condition of slinding mode control for the yaw error compensating servo-system has been established. From some experimental results by using an experimental set-up, the sliding mode control showed its effective in disturbance rejection and its performance was superior to conventional linear controls.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.1045-1049
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• 1996

For the precision positioning and tracking control, the proper friction compensation is essential. The friction causes steady state error. The friction compensation based on the velocity and the controlling input or the desired velocity provides limited performance if the compensation value is fixed. In this paper, a friction compensation scheme using a fuzzy logic is proposed. The friction compensation amount is adjusted depending on the velocity and controlling input. The proposed fuzzy friction compensator with a pole-assignment controller is implemented in a linear positioning system. To illustrate the effectiveness of this scheme, computer simulations and experiments are carried out for the cases of no friction compensation, the proposed fuzzy friction compensation, and another friction compensation scheme based on velocity and control input, and the results are compared with each other.

• 한국기계가공학회지
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• 제16권2호
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• pp.88-93
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• 2017

Due to the requirement of the development of the precision manufacturing industry, the accuracy of machine tools has become a key issue in this field. A critical factor that affects the accuracy of machine tools is the feed system, which is generally driven by a ball screw. Basically, to improve the performance of the feed drive system, which will be thermally extended lengthwise by continuous usage, a thermal error compensation system that is highly dependent on the feedback temperature or positioning data is employed in the machine tool system. Due to the overdependence on measuring technology, the cost of the compensation system and low productivity level are inevitable problems in the machine tool industry. This paper presents a novel feed drive thermal error compensation system method that could compensate for thermal error without positioning or temperature feedback. Regarding this thermal error compensation system, the heat generation of components, principal of compensation, thermal model, mathematic model, and calculation method are discussed. As a result, the test data confirm the correctness of the developed feed drive thermal error compensation system very well.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.378-391
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• 2002

A 250mm stroke aerostatic stage, which detects position with laser scale and is driven by linear motor, is made and analyzed positioning error in 20$\pm$ 0.5 $^{\circ}C$ controlled atmosphere, aiming at investigating positioning characteristic of ultra-precision stage. We prove this aerostatic stage has a 10nm micro step resolution by experiment. By means of analyzing laser interferometer system, the scale of measuring error is about 0.2-0.4$\mu\textrm{m}$ according to refractive index error from missing the temperature change. To improve laser interferometer system, compensate refractive index error using measuring data from thermocouple. And, confirm 0.10$\mu\textrm{m}$ repeatability and 0.13 $\mu\textrm{m}$ positioning accuracy using the compensating refractive index. Also, we confirm 0.07 ${\mu}{\textrm}{m}$ repeatability of the stage using capacitive displacement sensor.

• 한국정밀공학회지
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• 제17권12호
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• pp.26-33
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• 2000

• 한국통신학회논문지
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• 제34권10A호
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• pp.727-735
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• 2009

UWB (Ultra Wide Band) 무선 측위에서 정화한 위치 정보를 추정하기 위해서는 무선 측위 과정에서 발생하는 오차를 보상하기 위한 알고리즘이 반드시 필요하다. 이러한 무선 측위 오차를 보상하고 정확한 위치 정보 추정이 가능한 Scanning 기법은 동일한 태그 위치에 대한 무선 측위를 반복하여 얻을 수 있는 위치 정보 후보군의 무게중심 점을 찾는 기법으로 처리 구조가 비교적 간단하고 정확한 위치 정보를 추정할 수 있는 장점이 있지만, 측위용 비콘 범위 내의 scanning 좌표들을 하나하나 탐색하고 연산해야하는 단점이 있다. 본 논문에서는 Scanning 기법의 높은 연산량을 줄이기 위해 유전자 알고리즘 (Genetic Algorithm)과 블록 윈도잉 (Block Windowing)의 적용 방안을 제안한다. 제안하는 기법의 성능 검증을 위하여 IEEE 802.15.4a TG에서 제시한 채널 환경에서 얻은 거리 인지 오차 (ranging error) 정보를 사용하였으며, 모의실험 결과를 통하여 낮은 연산량으로도 기존 Scanning 기법의 위치 추정 정확도에 근사할 수 있음을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 B
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• pp.679-681
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• 1995

In this paper, a friction compensation scheme using a fuzzy logic is presented. For the precision positioning and tracking control, the proper friction compensation is essential. Friction compensation schemes based on velocity and controlling input or desired velocity, have limitations because the compensation values are fixed. In this paper, a fuzzy friction compensation scheme adjusts the compensation value depending on the velocity and the position error. The proposed fuzzy friction compensator is implemented in a linear positioning system. The performance is illustrated by simulations and experiments.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.278-282
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• 1997

Thermal expension of the ball screw in semi-closed loop type CNC Lathe directly introduces positioning error along the travel axis. In this paper the thermal displacement of the ball screw is estimated by using macro variabie. The estimated dispacement of the ball screw are given to the NC in the form of pitch error compensation data into time interval. The thermal behaviour of the ball screw of the CNC Lasthe under the constant driving conditions was measured to examine the effectiveness of this compensation method. The results showed that thermal displacment of the ball screw were the positioning accuracy could be maintained to better then 6 .mu.m while using this compensation.

• 한국정밀공학회지
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• 제16권7호
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• pp.66-72
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• 1999

Robot calibration is very important to improve the accuracy of robot manipulators. However, the calibration procedure is very time consuming and laborious work for users. In this paper, we propose a method of relative error compensation to make the calibration procedure easier. The method is completed by a Pi-Sigma network architecture which has sufficient capability to approximate the relative relationship between the accuracy compensations and robot configurations while maintaining an efficient network learning ability. By experiment of 4-DOF SCARA robot, KIRO-3, it is shown that both the error of joint angles and the positioning error of end effector are drop to 15$\%$. These results are similar to those of other calibration methods, but the number of measurement is remarkably decreased by the suggested compensation method.

• 전자공학회논문지SC
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• 제41권2호
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• pp.17-28
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• 2004

퍼지논리를 이용한 XY 테이블의 데드존 보상기법을 제안한다. 퍼지논리 함수의 분류특성은 다양한 영역을 가진 데드존에 의해 유발되는 오차를 제거하기 위한 보상기 설계를 가능케 한다. 데드존 보상이 적응적이고 추적오차와 파라미터 추정치가 유계가 되는 퍼지논리 파라미터 동조알고리듬과 안정도 증명을 제시한다. 퍼지논리 데드존 보상기를 위치 테이블에 실험함으로써 데드존의 해로운 영향을 줄이는 효과를 보여준다.