• 로봇학회논문지
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• 제9권1호
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• pp.67-77
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• 2014

An electric motor is the one of the most important parts in robot systems, which mainly drives the wheel of mobile robots or the joint of manipulators. According to the requirement of motor performance, the controller type and parameters vary. For the wheel driving motors, a speed tracking controller is used, while a position tracking controller is required for the joint driving motors. Moreover, if the mechanical parameters are changed or a different motor is used, we might have to tune again the controller parameters. However, for the beginners who are not familiar about the controller design, it is hard to design pertinently. In this paper, we develop a nominal robust controller model for the velocity tracking of wheel driving motors and the position tracking of joint driving motors based on the disturbance observer (DOB) which can reject disturbances, modeling errors, and dynamic parameter variations, and propose the methodology for the determining the least control parameters. The proposed control system enables the beginners to easily construct a controller for the newly designed robot system. The purpose of this paper is not to develop a new controller theory, but to increase the user-friendliness. Finally, simulation and experimental verification have performed through the actual wheel and joint driving motors.

• 한국전자통신학회논문지
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• 제17권5호
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• pp.859-866
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• 2022

능동 외란제거 제어기는 루엔버거 관측기를 이용하여 상태변수를 추정하여 제어기에서 외란을 제거하는 방식이다. 루엔버거 관측기는 정상상태에서 상수의 특징을 갖는 외란을 포함하는 비선형항을 상태변수로 정의하여 추정한다. 추정된 상태변수 값을 비례적분 제어기와 적분비례 제어기에 보상하여 개선된 속도 추종 성능을 보일 수 있다. 추정된 상태의 오차는 부하변동의 경우 1.9 [%] 이내임과 정상상태 상태 추종 오차가 영으로 수렴함을 보여 상태 추종 제어기의 외란 제거성능을 보임을 확인할 수 있다.

• 핵의학기술
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• 제12권1호
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• pp.49-56
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• 2008

Purpose: Whole body imaging with radioiodine can detect functioning metastases. Non-physiologic I-131 uptake detected on images usually is interpreted as suggesting functioning thyroid metastases. However, extra-thyroidal I-131 accumulation does not always imply thyroid cancer metastases and has been reported in many circumstances. In order to avoid unnecessary therapeutic interventions it is important to distinguish false-positive sites of I-131 localization. We study here to remove false-positive sites around esophagus region on I-131 whole body imaging in patients who were administrated thyroidectomy. Materials and Methods: From April to August in 2007, we had the patients who had visited our department after they received thyroidectomy due to thyroid cancer. They were given I-131, and performed radioiodine body scan after 41 to 50 hours. Patients were whole-body-scanned for the speed of 8 cm per minute. After that, we took anterior and posterior static images around the patients' neck measured by 300 thousand counts per image. We selected 44 patients who had hot spots around neck region, we divided the patients into two groups. One group was given 0.5 L of water and the other group was given 0.5 L of water with 1 g of Vitamin C dissolved. The patients were asked to drink the fluid for one minute in sitting position and after that, we measured 300 kilo counts per image again. We compared prior anterior, posterior static images with anterior, posterior images after the patients had water or water that Vitamin C resolved. Results: In using water, both observer 1 and 2 interpreted 6 patients were washed out. In the water with Vitamin C resolved, observer 1 and 2 interpreted 9 and 8 patients were washed out. Observer 1 and 2 interpreted 6 and 5 patients had 'indeterminate' when they used water. Both observer 1 and 2 interpreted 6 patients had 'indeterminate' when they used water with Vitamin C resolved. When they used water, observer 1 interpreted 10 patients had 'unchanged' and observer 2 interpreted 11 patients had 'unchanged'. Differently, when they used water with vitamin C resolved, observer1 had 8 patients having 'unchanged'and observer 2 had 9. Conclusion: As a result, by making patients drink 0.5 liter of water which has vitamin C resolved helped getting rid of false-positive sites in esophagus. Therefore, based on this study, we believe that drinking water with vitamin C dissolved is very in terms of reducing false-positive hot spot around the esophagus for the iodine-131 whole body scan.

• Journal of Power Electronics
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• 제4권1호
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• pp.1-11
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• 2004

A stable adaptive sensorless speed controller for three-level inverter fed induction motor direct torque control (DTC) system using the radial-basis function network (RBFN) is presented in this paper. Torque ripple in the DTC system for high power induction motor could be drastically reduced with the foregoing researches of switching voltage selection and torque ripple reduction algorithms. However, speed control performance is still influenced by the inherent uncertainty of the system such as parametric uncertainty, external load disturbances and unmodeled dynamics, and its exact mathematical model is much difficult to be obtained due to their strong nonlinearity. In this paper, the inherent uncertainty is approximated on-line by the RBFN, and an additional robust control term is introduced to compensate for the reconstruction error of the RBFN instead of the rich number of rules and additional updated parameters. Control law for stabilizing the system and adaptive laws for updating both of weights in the RBFN and a bounding constant are established so that the whole closed-loop system is stable in the sense of Lyapunov, and the stability proof of the whole control system is presented. Computer simulations as well as experimental results are presented to show the validity and effectiveness of the proposed system.

• 한국정보통신학회논문지
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• 제15권4호
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• pp.886-890
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• 2011

유도전동기는 상대적으로 저가이며 보수가 용이하여 산업 및 여러 분야에서 많이 사용되고 있는 전동기이다. 유도전동기의 정확한 속도 및 토크 제어를 위해서 회전자의 속도 및 위치정보가 요구된다. 회전자의 위치 및 속도 센서들은 경제성 및 주위 환경에 따른 센서의 신뢰도 감소 문제를 가져온다. 최근에는 이러한 경제성 및 신뢰성 향상을 위하여 속도 및 위치센서를 사용하지 않는 센서리스 제어방식의 연구가 많이 이루어지고 있다. 대부분의 센서리스제어 방식에서 위치 및 속도추정은 전동기 전압방정식으로부터 계산된다. 따라서 파라미터 오차는 센서리스 제어성능에 큰 영향을 미치게 된다. 본 논문에서는 유도전동기의 속도 추정에서 회전자 저항 오차에 의해 발생하는 속도 오차를 보상하기 위하여 회전자 저항 보상방식을 제안한다. 본 논문에서 제안한 방식은 컴퓨터 시뮬레이션 및 실험을 통하여 검증한다.

• Journal of Power Electronics
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• 제15권6호
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• pp.1547-1558
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• 2015

A predictive functional control (PFC) scheme for permanent magnet synchronous motor (PMSM) servo systems is proposed in this paper. The PFC-based method is first introduced in the control design of speed loop. Since the accuracy of the PFC model is influenced by external disturbances and speed detection quantization errors of the low distinguishability optical encoder in servo systems, it is noted that the standard PFC method does not achieve satisfactory results in the presence of strong disturbances. This paper adopted the Kalman filter to observe the load torque, the rotor position and the rotor angular velocity under the condition of a limited precision encoder. The observations are then fed back into PFC model to rebuild it when considering the influence of perturbation. Therefore, an improved PFC method, called the PFC+Kalman filter method, is presented, and a high performance PMSM servo system was achieved. The validity of the proposed controller was tested via experiments. Excellent results were obtained with respect to the speed trajectory tracking, stability, and disturbance rejection.

• ETRI Journal
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• 제37권6호
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• pp.1165-1175
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• 2015

This paper presents an advanced sensorless permanent magnet (PM) brushless motor controller integrated circuit (IC) employing an automatic lead-angle compensator. The proposed IC is composed of not only a sensorless sine-wave motor controller but also an isolated gate-driver and current self-sensing circuit. The fabricated IC operates in sensorless mode using a position estimator based on a sliding mode observer and an open-loop start-up. For high efficiency PM brushless motor driving, an automatic lead-angle control algorithm is employed, which improves the efficiency of a PM brushless motor system by tracking the minimum copper loss under various load and speed conditions. The fabricated IC is evaluated experimentally using a commercial 200 W PM brushless motor and power switches. The proposed IC is successfully operated without any additional sensors, and the proposed algorithm maintains the minimum current and maximum system efficiency under $0N{\cdot}m$ to $0.8N{\cdot}m$ load conditions. The proposed IC is a feasible sensorless speed controller for various applications with a wide range of load and speed conditions.

• 한국산학기술학회논문지
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• 제7권6호
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• pp.1092-1099
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• 2006

본 논문에서는 유도전동기를 인버터와 같은 전력변환장치를 사용하여 정상상태의 동작특성은 물론 과도특성까지 해석하기 위해서는 유도전동기와 부하를 포함하는 전체 시스템의 정확한 동적 모델링을 이용하여 시스템 방정식으로 표현해야 한다. 또한 최대 견인력 제어를 위해서 속도센서리스벡터제어와 부하 토크 외란 관측기를 통하여 점착력 계수를 추정한다. 이와 같은 시스템의 제어 알고리즘을 구현하기 위하여 철도 모의 장치를 이용하여 제안된 알고리즘을 시뮬레이션과 실험을 통하여 확인하고, 철도 차량의 속도 가감에 따른 공전속도에 대한 점착력의 관계 등 제반 사항을 모의 장치에 의해서 구현하였다.

• Journal of Ship and Ocean Technology
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• 제10권4호
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• pp.34-48
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• 2006

The visual observation of wave condition depends on the observer's skill and experience. Also, the environmental conditions such as light and cloud heavily influence the visual measurement. In the speed test of sea trial, the wave measurement should be objective and accurate. In this paper, the problems of visual measurement and their effects on speed test are described. To overcome those problems, we developed the wave measurement system using commercial marine X-band radar, WaveFinder. The system installed at inland base was calibrated by waverider buoy and then the system's operability was defined. Onboard tests had also been performed three times for formal wave measurement to correct the ship speed. The results illustrated very good agreement with visual observation by experts. It can be concluded that the system would be useful to measure wave and swell information for the sea trial, irrespective of day and night.

• 한국전자통신학회논문지
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• 제17권5호
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• pp.867-872
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• 2022

부하의 영향은 전동기의 정밀한 속도조절에 있어서 중요한 요소이다. 본 연구에서는 수학적 모델로 용이하지 않은 부하 및 수학적 모델의 오차와 비선형항을 포함하는 외란을 하나의 상태로 정의하고, 이를 추정할 수 있는 상태 관측기를 설계한다. 그리고 상태 관측의 추정오차가 0으로 수렴할 수 있도록 관측이득을 설정하고, 추정된 상태를 백스텝핑 제어기에 사용하여 정밀한 속도 추종이 가능한 제어기를 설계한다. 1 [hw] 급의 매입형 영구자석 동기전동기에 적용한 결과 우수한 상태관측과 추종 성능을 확인할 수 있다.