• 대한전기학회논문지:시스템및제어부문D
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• 제53권12호
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• pp.827-833
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• 2004

In active noise control (ANC) systems, the error-reduction performance of the conventional Filtered-X Least Mean Square (FXLMS) algorithm may be affected by nonlinear distortions in the secondary path such as in the power amplifiers, loudspeakers and transducers. In this paper, a nonlinear FXLMS algorithm with high error-reduction performance is proposed to compensate for undesirable nonlinearities in the secondary-path of ANC systems by employing the inverse Volterra filtering approach. In particular, the proposed approach is based on the utilization of the conventional P-th order inverse approach to nonlinearity compensation in the secondary path of ANC systems. Finally, the simulation results showed that the proposed approach yields a better nonlinearity compensation performance for the ANC systems with a nonlinear secondary path than the conventional FXLMS.

• 한국정밀공학회지
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• 제15권11호
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• pp.137-144
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• 1998

In this paper we present our research dealing with the problem of tool deflection during the milling. We try to compensate the errors by considering a new tool trajectory. In order to determine the compensated tool trajectory, the problem is divided in three steps : cutting forces model, tool deflection model and trajectory compensation. Starting from experimental data, we determine a cutting forces model., which allows us to anticipate the tool deflection along one nominal path. In order to determine the compensated tool trajectory, we propose in this paper a method of path compensation, called “mirror method”. This method of tool path optimization allows to minimize errors due to tool deflection. Several examples are processed in simulations and validated experimentally.

• 한국정밀공학회지
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• 제12권2호
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• pp.97-111
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• 1995

In this paper, we investigate path compensation scheme for the machining errors due to tool deflection in 2D contour machining. The significance of the deflection error is first shown by experiments, and a direct compensation scheme is sought. In the presented scheme, the tool path is evaluated and correcte based on the instantaneous deflection force model, until the desired contour can be obtained under the presence of tool deflection in actual machining. In the sense that the developed method estimates and compensates the machining errors via modifying the tool path, it is distinguished from the previous approach based on geometric simulation and cutting simulation. Further, it can be viewed as a direct and active method toward direct shape control in CNC machining. Simulation results are included to show the validity and adequacy of the path-modification scheme under various cutting conditions.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2311-2318
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• 2005

Progress in the LCD industries has been very rapid. Therefore, their manufacturing lines require larger LCD glass-handling robots and more precise path control of the robots. In this paper, we present two practical advanced algorithms for high-precision path generation of an LCD glass-handling robot. One is high-precision path interpolation for continuous motion, which connects several single motions and is a reliable solution for a short robot cycle time. We demonstrate that the proposed algorithm can reduce path error by approximately 91% compared with existing algorithms without increasing cycle time. The second is real-time static deflection compensation, which can optimally compensate the static deflection of the handling robot without any additional sensors, measurement instruments or mechanical axes. This reduces vertical path error to approximately 60% of the existing system error. All of these algorithms have been commercialized and applied to a seventh-generation LCD glass-handling robot.

• The Journal of the Acoustical Society of Korea
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• 제21권1E호
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• pp.25-30
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• 2002

We report on the development of a fiber optic hydrophone consists of a sensing Michelson interferometer and a compensating Mach-Zehnder interferometer for optical path length compensation. The double interferometer configuration has the following advantages: the hydrophone can be made more small; a laser source with a relatively short coherence length can be used; and the compensating interferometer can be located near the signal processing electronics, far away from the sensing interferometer and noise introduced by reference arm can be greatly reduced. The performance of the hydrophone is evaluated experimentally by immersing the sensing interferometer in a water tank to detect underwater acoustic signals generated by an acoustic wave projector. Experimental results show that over the frequency range of 1 to 4 kHz, the hydrophone has an almost flat response with an average normalized sensitivity of -302 dB re 1/ μ Pa.

• 제어로봇시스템학회논문지
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• 제12권3호
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• pp.248-254
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• 2006

It is necessary to improve the exactness and adaptation of the working environment for the intelligent robot system. The vision sensor have been studied for a long time at this points. However, it has many processes and difficulties for the real usages. This paper proposes a visual servoing in the virtual environment to support OLP(Off-Line-Programming) path compensation and supplement the problem of complexity of the old kinematical calibration. Initial robot path could be compensated by pixel differences between real and virtual image. This method removes the varies calibrations and 3D reconstruction process in real working space. To show the validity of the proposed approach, virtual space servoing with stereo camera is carried out with WTK and openGL library for a KUKA-6R manipulator and updated real robot path.

• International Journal of Precision Engineering and Manufacturing
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• 제9권4호
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• pp.26-31
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• 2008

A precision four-degree-of-freedom measurement system has been developed for simultaneous measurement of four motion errors of a linear stage, which include straightness and angular errors, The system employs a retro-reflector to detect the straightness errors and a plane mirror to detect the angular errors. A common-path compensation method for laser beam drift is put forward, and the experimental results show that the influences of beam drift on four motion errors can be reduced simultaneously. In comparison with the API 5D laser measuring system, the accuracy for straightness measurement is about ${\pm}1.5{\mu}m$ within the measuring range of ${\pm}650{\mu}m$, and the accuracy for pitch and yaw measurements is about ${\pm}1.5$ arc-seconds within the range of ${\pm}600$ arc-seconds.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.565-567
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• 2004

In active noise control (ANC) systems, the convergence behavior of the conventional Filtered-X Least Mean Square (FXLMS) algorithm may be affected by nonlinear distortions in the secondary path (e.g., in the power amplifiers, loudspeakers, transducers, etc.), which may lead to degradation of the error-reduction performance of the ANC systems. In this paper, a stable FXLMS algorithm with fast convergence is proposed to compensate for undesirable nonlinear distortions in the secondary-path of ANC systems by employing the Volterra filtering approach. In particular, the proposed approach is based on the utilization of the conventional P-th order inverse approach to nonlinearity compensation in the secondary path of ANC systems. Finally, the simulation results showed that the proposed approach yields a better convergence behavior In the nonlinear ANC systems than the conventional FXLMS.

• 대한전자공학회논문지TC
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• 제49권5호
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• pp.27-36
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• 2012

본 논문에서는 스마트 안테나 시스템에 대해 경로 결함들의 보정과 전력 증폭기의 비선형성 보상을 결합하는 새로운 기술을 제안하였다. 배열 안테나의 각각의 경로들이 동일한 특성을 갖기 위한 보정과 보상을 위해 선형 항에 3차 항을 추가한 다항식과 간접 학습 구조를 사용하였다. 본 논문에서는 컴퓨터 모의실험을 통해 성능을 입증하였다. 모의실험 결과, 단 하나의 3차 항을 추가하여 선형 결함들뿐만 아니라 모든 비선형 효과까지 효율적으로 보상함을 확인하였다.

• 한국통신학회논문지
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• 제37권4A호
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• pp.197-204
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• 2012

본 논문에서는 피드포워드 방식을 이용하여 전력 증폭기의 비선형성 보상과 스마트 안테나 시스템의 경로 결함 보정을 결합하는 새로운 기술을 제안하였다. 배열 안테나의 각각의 경로들이 동일한 특성을 갖도록 하기 위한 보상과 보정을 위해 선형 식에 3차 항을 추가한 다항식과 피드포워드 방식을 사용하였다. 이 방식은 원래의 기저대역 신호를 변형하지 않으므로, 시스템의 기저대역 부와는 독립적인 스마트 안테나 시스템에 적용할 수 있다. 컴퓨터 모의실험을 통하여, 단 하나의 3차 항을 추가함으로써 전력 증폭기의 비선형 효과를 효율적으로 보상하고, 배열 안테나의 각 경로의 선형 결함들 역시 부차적으로 보정할 수 있다.