• 한국산업융합학회 논문집
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• 제19권1호
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• pp.10-17
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• 2016

In general, articulated robot control technology is limited to the design of robot arm control systems considering each joint of the robot joint as a simple servomechanism. This method describes the varying dynamics of a manipulator inadequately because it neglects the motion and configuration of the whole arm mechanism. The changes of the parameters in the controlled system are significant enough to render conventional feedback control strategies ineffective. This basic control system enables a manipulator to perform simple positioning tasks such as in the pock and place operation. However, joint controllers are severely limited in precise tracking of fast trajectories and sustaining desirable dynamic performance for variations of payload and parameter uncertainties. In many servo control applications the linear control scheme proposes unsatisfactory, therefore, a need for nonlinear techniques that increasing. for Forging process automation.

• 한국정밀공학회지
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• 제15권2호
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• pp.114-123
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• 1998

In the end milling process, the information of the surface errors plays an important role in adaptive control systems for precision machining. As the measuring accuracy of the surface errors directly matches the control's, it is an important factor for evaluating the performance of the system. In order to obtain the surface errors, the prediction using the cutting force, torque, motor power etc. is frequently practiced owing to the easiness in measurement. In the implementation of the prediction, the information on the cutting depths make it concrete and precise. Actually the axial depth of cut limits the range of the calculation. In general, it is not easy to know the cutting depths due to irregular shape of workpieces, inaccurate positioning of them on the table of machine tool, and machining error in the previous cutting. In addition to, even if cutting depths are informed, it is difficult to match the individual position of the cutter on the varying shape of the work material. This work suggests an algorithm estimating the cutting depths based on cutting force and makes it precise to predict the surface error. The proposed algorithm can be applied in more extensive cutting situations, such as presence of the tool wear, change of the work material hardness, etc.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제12B권1호
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• pp.1-6
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• 2002

The severe problem in improving the positioning precision of a permanent magnet linear synchronous motor (PMLSM) is the large detent farce caused by the permanent magnet arrangement. It is generally an undesired effect that contributes to the torque ripple, vibration and noise of machine. The detent force is arisen from the difference of the position of a permanent magnet end and a tooth position. In this paper, the four methods to reduce detent force were studied and analyzed. The methods are adjusting the width of permanent magnet, varying the shape of armature teeth, relocating the permanent magnet, and adjusting the width of permanent magnet and relocating the permanent magnet at the same time. To analyze the detent farce according to flour methods, a two-dimensional Finite Element Analysis [FEA] was used and we compared with the ratio of reduction of the detent farce according to the flour methods.

• 제어로봇시스템학회논문지
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• 제15권5호
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• pp.538-542
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• 2009

Industrial manipulators have been mostly used in large companies such as automakers and electronics companies. In recent years, however, demands for industrial manipulators from small and medium-sized enterprises are on the increase because of shortage of manpower and high wages. Since these companies cannot hire robot engineers for operation and programming of a robot, intuitive teaching and playback techniques of a robot manipulator should replace the robot programming which requires substantial knowledge of a robot. This paper proposes an intuitive teaching and playback algorithm used in assembly tasks. An operator can directly teach the robot by grasping the end-effector and moving it to the desired point in the teaching phase. The 6 axis force/torque sensor attached to the manipulator end-effector is used to sense the human intention in teaching the robot. After this teaching phase, a robot can track the target position or trajectory accurately in the playback phase. When the robot contacts the environment during the teaching and playback phases, impedance control is conducted to make the contact task stable. Peg-in-hole experiments are selected to validate the proposed algorithm since this task can describe the important features of various assembly tasks which require both accurate position and force control. It is shown that the proposed teaching and playback algorithm provides high positioning accuracy and stable contact tasks.

• 대한치과교정학회지
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• 제32권6호
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• pp.401-411
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• 2002

정교한 교합을 달성하기 위해서는 브라켓을 정확하게 위치시키는 것이 필수적이다. 그러나, 많은 원인에 의해 브라켓의 위치가 변할 수 있다. 본 연구는 브라켓의 수직적 위치에 변화가 있을 때 이것이 치관경사도에 미치는 영향을 연구하고자 함이다. 연구대상으로는 서울대학교 치과대학 교정학교실의 정상교합자 표본 중 상태가 양호한 10명(남자 6명, 여자 4명, 평균 연령 22.3세)을 대상으로 하였으며 , 이들의 치아모형을 laser scanner를 이용, 3차원적으로 스캔을 시행하였고, 컴퓨터 프로그램 상에서 스캔된 치아모형에 대한 계측을 실시하였다. 각 모형에 대하여 Bracket plane을 설정하였고, 각 치아에서 Bracket plane에 수직이며 치아의 장축을 지나는 Tooth plane을 순협면에서 결정한 뒤 Bracket plane상에서의 치관경사도를 계측하였다. 이로부터 Bracket plane을 상하로 0.5mm, 1.0mm, 1.5mm 변위시켰을 때의 치관경사도를 계측하였다. 각 계측 항목에 대해 일원분산분석 (oneway ANOVA)과 Duncan's multiple comparison test를 시행하였다. 이상의 연구로부터 다음과 같은 결과를 얻었다. 1. 상악중절치, 측절치, 견치, 대구치와 하악소구치, 대구치에 있어서 브라켓의 수직적 위치가 변화함에 따라 치관경사도가 통계적으로 유의성 있게 차이 있는 것으로 나타났다(p<0.05). 2. 상악전치와 대구치, 하악소구치와 대구치에서는 기준평면으로부터 수직적으로 같은 양만큼 변위되었다 할지라도 보다 교합면쪽에 위치하는지, 보다 치은쪽에 위치하는지에 따라 치관경사도의 변화량이 다르게 나타났다. 3. 브라켓의 수직적 위치변화가 있을 경우 상악전치부와 대구치, 하악구치부, 이 중 특히 하악구치부의 치관경사도는 임상적으로 영향을 받게 되므로 브라켓을 위치시킬 때 주의를 요해야 할 것으로 생각된다.

• Journal of Electrical Engineering and Technology
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• 제8권1호
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• pp.90-96
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• 2013

As the need of electric motor is increased rapidly throughout our society, the various application fields are created and the service market called robot gets expanded as well as the existing industrial market. Out of those, the joint systems such as humanoid that is servo actuator for position control or all fields which require multi-degree of freedom (multi-DOF) require the development of innovative actuator. It is multi-DOF spherical motor that can replace the existing system in multi-DOF operating system. But, multi-DOF spherical motor that has been researched up to date is at the stage which is insufficient in performance or mechanical practicality yet. Thus, first of all the research results and limitation of the previously-researched guide frame-type spherical motors were analyzed and then the feature of double air-gap spherical motor which was devised to complement that was studied. The double air-gap multi-DOF spherical motor is very suitable spherical motor for system applying which requires the multi-DOF operation due to its simple structure that does not require other guide frame as well as performance improvement due to its special shape which has two air-gaps. So, the validity of the study was verified by designing and producing it with 3D-FEM through the exclusive jig for multi-DOF spherical motor.

• 한국정밀공학회지
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• 제22권10호
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• pp.174-185
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• 2005

This paper presents the design, fabrication, and testing results of a dual stage actuator system for a fine positioning of magnetic heads in magnetic disk drives. A novel rotary microactuator which is electrostatically driven and utilized as a secondary actuator was designed. The stator and rotor electrodes in the microactuator was revised to have the optimal shapes and hence produces much higher rotational torque compared with the conventional comb-shape electrodes. The microactuators were successfully fabricated using SoG(silicon on glass) processing technology, which is known as being cost-effective. The fabricated microactuator has the structural thickness of $45{\mu}m$ with the gap width of approximately $3{\mu}m$. The dynamic characteristic of microactuator/slider assembly was investigated, and its natural frequency and DC gain were measured to be 3.4kHz and 32nm/V, respectively. The microactuator/slider assembly was integrated into a HDD model V10 of Samsung Electronics Co. and a dual servo algorithm was tested to explore the tracking performance of dual stage actuator system where the LDV signals instead of magnetic head signals were used. Experimental results indicate that this system achieves the tracking accuracy of 30nm. This value corresponds to a track density of 85,000 track per inch(TPI), which is about 3 times greater than that of current hard disk drives.

• 한국융합학회논문지
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• 제9권11호
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• pp.291-297
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• 2018

의료 현장에서의 최소침습수술(MIS)의 어려움 때문에 시뮬레이터 훈련이 활발히 연구되고 있다. 이를 위해 본 연구에서는 S-chain모델을 사용하여 가상 장기와 변형과정을 표현하고 반발력 제공이 가능한 햅틱 시뮬레이터를 개발하고자 한다. S-chain알고리즘의 주요 원리는 반발력이 체인 요소의 수에 비례하는 것이며, 대상인 장기의 변형이 클수록 많은 계산시간을 요구한다. 이에 본 연구에서는 계산속도가 개선된 S-chain알고리즘을 회전움직임에 적용하여 제어성능을 평가하였다. 본 연구에서는 자기 점성 점성(MR) 유체를 사용하는 햅틱 마스터 시스템을 제안하고 S-chain모델을 개발한다. 결과적으로, 이 S-chain모델을 사용하여 가상의 장기와 실제 마스터 장치를 결합함으로써 반발력과 수술로봇의 좌표 위치를 서로 전달하는 햅틱 시스템을 구축하여, 햅틱 시뮬레이터의 제어 성능을 실험을 통해 평가하였다.

• 문화기술의 융합
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• 제10권3호
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• pp.801-807
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• 2024

선형 로봇은 자동화 시스템에서 부품의 이송이나 위치 결정에 널리 사용되며 보통 높은 정밀도가 요구된다. 선형 로봇을 응용한 시스템의 제작회사에서는 로봇의 이상 유무를 작업자가 판단하는데, 작업자의 숙련도에 따라 이상 상태를 판단하는 정확도가 달라진다. 최근에는 인공지능 등의 기술을 사용하여 로봇 스스로 이상을 검출하는 방법에 관한 연구가 진행되고 있다. 본 논문에서는 전이 학습을 이용하여 선형 로봇의 볼 스크류 정렬 이상과 선형 레일 정렬 이상을 검출하는 시스템을 제안하고 가속도 센서와 토크 센서 정보를 이용한 별개의 실험을 통해 제안한 시스템의 이상 검출 성능을 검증 및 비교한다. 센서로부터 얻어진 신호를 스펙트로그램 이미지로 변환한 후, 영상 인식 인공지능 분류기를 사용하여 이상의 종류를 진단하였다. 제안한 방법은 선형 로봇뿐만 아니라 일반적인 산업용 로봇에도 적용할 수 있을 것으로 기대한다.