• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.1091-1093
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• 2002

In this paper, the load torque observer is designed for speed and torque control of DC motor. Load torque is very sensitive to the variation and disturbance of the input parameters. The proposed system can accurately estimate the instantaneous speed even at the low speed range by using the load torque observer based on the torque component of DC motor. The system becomes robust against disturbances using a feed-forward control of the load torque estimated automatically at the speed observer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.170-173
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• 2005

This paper presents an Fuzzy-Neuro Observer system for an ac servo motor dirve to track periodic commands using a neuro-fuzzy observer. AC servo motor drive system is rather similar to a linear system. However, the uncertainties, such as machanical parametric variation, external disturbance, uncertainty due to nonideal in transient state. therefore an intelligent control system that isan on-line trained neural network controller with adaptive learning rates.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1-6
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• 1991

This paper is concerned with the design of a robust tracking controller using a state observer on a robotic manipulator under the disturbance. The controller is designed to follow a step or ramp reference input without steady state error in the presence of a disturbance and a system parameter variation. In most cases, since all the state vectors are not measured, unmeasurable state vectors must be estimated or reconstructed. A reduced order observer is proposed to estimate unmeasurable state vectors of the non-linear system. Some problems are caused by the Coulomb friction, the disturbance, and the spring effect of a link between the drive motor and the manipulator arm. The state variables, directly measured and estimated by the reduced order observer, are fed back to the controller. When the robot system exhibits the 'limit cycle, the feedback gains initially obtained by optimal control theory are changed. As a result, the limit cycle is eliminated by the new controller gains,

• 대한기계학회논문집A
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• 제26권9호
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• pp.1795-1805
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• 2002

A position controller which can achieve a specified dynamic performance irrespective of the different operating position of the pneumatic cylinder is proposed. The position controller developed in this paper is composed of a nonlinear compensator and a disturbance observer. The nonlinear compensator which feeds back position, velocity and acceleration is derived from the nonlinear dominating equations of the position control system to compensate for variation of dynamic characteristics of a pneumatic cylinder according to the change of the operating position. The disturbance observer including a simplified linear model is designed to reduce the effect of model discrepancy in the low frequency range which cannot be suppressed by the nonlinear compensator. The results of the experiments show that the position control performance maintains a designed performance regardless of the variations of an operating position of the pneumatic cylinder.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.692-697
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• 2001

A precise tracking control scheme on the system in presence of nonlinear dynamic friction is proposed. In this control scheme, the standard SMC is combined with the nonlinear observer to estimate the dynamic friction state that is impossible to measure. Then this control scheme has the good tracking performance and the robustness to parameter variation compared with the standard SMC and the PiD based nonlinear observer control system. This fact is proved by the experiment on the ball-screw driven servo system with the dynamic friction model.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.745-749
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• 2003

The iterative sliding mode observer is proposed to control sensorless PMSM(Permanent Magnet Synchronous Motor). Proposed sliding mode observer has the character which is robust to the disturbance and parameter variation. Low pass filter with the variable cutoff frequency is also proposed to compensate rotor angle, it is led to saving memory and minimizing operation time. Experimental results shows that the proposed sliding mode observer leads to the proper performance.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권8호
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• pp.500-508
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• 2004

This paper presents a new sensorless vector control system for high performance induction motor drives fed by a matrix converter with non-linearity compensation and disturbance observer. The nonlinear voltage distortion that is caused by commutation delay and on-state voltage drop in switching device is corrected by a new matrix converter modeling. The lumped disturbances such as parameter variation and load disturbance of the system are estimated by the radial basis function network (RBFN). An adaptive observer is also employed to bring better responses at the low speed operation. Experimental results are shown to illustrate the performance of the proposed system.

• 조명전기설비학회논문지
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• 제29권10호
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• pp.104-110
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• 2015

The disturbance observer (DOB) controller has been widely used in various industrial applications since it is capable of achieving robust stability and disturbance rejection. In this paper, we study the effect of Q-filter on disturbance observer controller for Electro-Magnetic suspension (EMS) systems. We consider three Q-filters and analyze their effects on the robust stability against parameter uncertainties due to mass variation. Moreover, we investigate the influence of sensor noise for three Q-filters. According to our study, robust stability improves as the order of Q-filter decreases. On the other hand, the larger the order of Q-filter, the more the effect of sensor noise can be removed.

• Asian Pacific Journal of Cancer Prevention
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• 제17권11호
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• pp.4867-4868
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• 2016

Prostatic adenocarcinoma is the commonest solid malignancy seen in Omani elderly males 60-80 years of age. The Gleason grade is the most widely used grading system for prostatic carcinoma and is recommended by the World Health Organization. A peer review was carried out at the Pathology Department of Sultan Qaboos University Hospital (SQUH), Oman, to assess the quality of reporting at the center. The aim of this study was to determine inter-observer variation among 7 pathologists working at a tertiary care center in Oman. A total of 47 consecutive prostatic biopsies were interdependently reviewed by seven pathologists and the results obtained were compared with each other and the original diagnosis. This peer review indicated a fair inter-observer agreement (0.482) among 7 pathologists in the department, with fair to moderate agreement when the results were compared to the reported diagnosis, comparable to the published literature. Dual and sub-specialty reporting are being instituted to improve the performance in this vital aspect of pathology.

• 전기전자학회논문지
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• 제26권4호
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• pp.653-658
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• 2022

본 논문에서는 온도 변화로 인한 영구자석 쇄교 자속 변화를 고려한 PMSM 드라이브의 MTPA(Maximum Torque per Ampere) 제어 알고리즘을 제시한다. 영구자석 쇄교 자속은 고정자 쇄교 관측기를 통해 실시간으로 추정되고, 추정된 영구자석 쇄교 자속으로부터 토크 오차 보정 계수가 계산된다. 2차원 MTPA look-up table(LUT)은 토크 오차를 보상하기 위해 영구자석 쇄교 자속 변화를 반영하는 MTPA 전류 궤적을 달성하기 위해 개발되었다. 제안된 PMSM의 MTPA 제어 알고리즘은 시뮬레이션을 통해 검증된다.