• 전기학회논문지
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• 제63권5호
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• pp.683-689
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• 2014

The paper introduces dynamic generation technique of foot trajectories for humanoid robots using CPG(Central Pattern Generator) and proposes adaptive walking method for slope terrains combining a feedback network. The proposed CPG based technique generates the trajectory of foot in the Cartesian coordinates system and it can change the step length adaptively according to the feedback information. To cope with variable slope terrains, the sensory feedback network in the CPG are designed using the geometry relationship between foot position and body center position such that humanoid robot can maintain its stability. To demonstrate the effectiveness of the proposed approach, the experiments on humanoid robot Nao are executed in the Webot simulation. The performance and motion features of the CPG based approach are compared and analyzed focusing on the adaptability in slope terrains.

• 대한기계학회논문집
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• 제19권6호
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• pp.1391-1401
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• 1995

This paper addresses design procedure and testing results of a closed-loop motion control of the cranes. When the object is stopped at the desired position, swinging occurs, and such swinging deteriorates the safety and efficiency of the operation of the crane. Therefore, in this paper, the cascade anti-swing and trolley position feedback controller are designed. Anti-swing controller rapidly eliminates swinging of object and position feedback controller reduces the trolley position error. The performance of this controller is investigated through the computer simulation and experiment. From the results of a series of computer simulations and experiments it can be concluded that proposed controller effectively reduces swinging of the object and trolley position error, which shows this controller can be used as an effective tool for the precise control of overhead cranes.

• 전자공학회논문지B
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• 제33B권4호
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• pp.27-40
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• 1996

This paper proposed a kinematic modeling methodlogy and feedback control system based on kinematics for 2 degrees of freedom of 4-wheeled mobile robot. We assigned coordinate systems to specify the transformation matirx and write the kinematic equation of motion. We derived the actuated inverse and sensed forwared solution for the calculation of actual robot orientation and the desired robot orientation. It is the most significant error and has the largest impact on the motion accuracy. To calculate the WMR position in real time, we introduced the dead-reckoning algorithm and composed two feedback control system that is based on kinematics. Through the simulation result, we compare with the ffedback control system for position control.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.213-218
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• 2003

The equipment of industrial robot in manufacturing and assembly lines has rapidly increased. In order to achieve high productivity and flexibility, it becomes very important to develop the visual feedback control system with Off-Line Programming System(OLPS). We can save much efforts and time in adjusting robots to newly defined workcells by using OLPS. A proposed visual calibration scheme is based on position-based visual feedback. The calibration program firstly generates predicted images of objects in an assumed end-effector position. The process to generate predicted images consists of projection to screen-coordinates, visible range test and construction of simple silhouette figures. Then camera images acquired are compared with predicted ones for updating position and orientation data. Computation of error is very simple because the scheme is based on perspective projection which can be also expanded to experimental results. Computation time can be extremely reduced because the proposed method does not require the precise calculation of tree-dimensional object data and image Jacobian.

• 제어로봇시스템학회논문지
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• 제5권7호
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• pp.787-793
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• 1999

A self-sensing magnetic suspension system utilizing a LC resonant circuit is proposed by using the characteristic that the inductance of the magnetic system is varied with respect to the air gap displacement. An external capacitor is added into the electric system to make the levitation system be statically stable system, which much relieves the control effort required to stabilize the magnetic suspension system of haying an intrinsic unstable nature. For the realization of the self- sensing magnetically levitated system, an amplitude modulation / demodulation method is used with a positive position feedback controller Experimental results are presented to validate the proposed method.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1992년도 춘계학술대회 논문집
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• pp.185-189
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• 1992

This paper prsents an end-point control of a one-link flexible arm with a payload by using closed loop control. Tip position of arm is shifted by the base motion according to DC servomotor, whivh is driven by a feedback signal composed of the tip displacement and the estimated tip velocity. The shifting problem of the arm from initial position to desired position is considered by the variation of the displacement gain Gd and velocity agin Gv. Theoretical results are obtained by applying the method of the Laplace transform to the governing equations and the method of numerical inversion. This system is composed of a flexible arm with payload, DC servomotor, and a ballscrew mechanism. The flexible arm is mounted on a mobile stage driven by a servomotor and ballscrew. In controlling the tip displacement of flexible arm, the fundamental bode vibration is supressed more rapidly with an increase of the velocity feedback gain Gv and the feedback displacemenmt gain Gd. Theretical responses are approximately in good agreement with those obtained experimentally.

• 조명전기설비학회논문지
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• 제24권9호
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• pp.129-135
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• 2010

The state feedback-based position controller for the voice coil motor(VCM) used in precise automated manufacturing processes is proposed and analyzed in this paper. The proposed controller has advantage over the conventional cascade-type P-PI controller in terms of the gain selection and the controller interference. The feasibility of the presented idea is verified by experimental results on a designed VCM.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2008년도 학술대회 1부
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• pp.749-753
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• 2008

자기수용감각은 신체 내부에서 폼의 발란스, 근육의 강도, 민첩성을 이용하여 공간의 위치나 관절의 움직임을 조절하는 능력으로 정의된다. 기존의 연구에서는 자기수용감각을 발달시키기 위하여 reaching 훈련을 이용한 시각적인 feedback을 제시하여 훈련을 하고 feedback을 차단하고 측정하는 방법이 사용했지만 시각적인 feedback이 있는 상황은 자기수용감각만 유도할 수 없는 문제점이 있다. 가상현실 기술은 훈련 동안 실시간으로 시각적인 feedback을 다양하게 제공하는 것으로 기존의 연구의 문제점을 해결할 수 있다. 본 연구에서는 가장현실 기술을 이용한 자기수용감각을 발달시키기 위한 훈련 및 평가시스템을 개발하고 파일럿 스터디를 하였다. 가상환경 task는 3개로 구성되었다. mode 1은 신체 움직임을 실시간으로 시각적인 feedback을 제시하는 환경이다. mode 2는 피험자의 반응에 의해서만 신체 움직임에 대한 시각적인 feedback을 제시하는 환경이다. mode 3응 시각적인 feedback을 제시하지 않는 환경이다. 가상환경의 task는 각 mode에서 3지점을 한 번씩 수행하는 것을 1회기로 5회기씩 수행하였다. 본 연구의 결과에서, target을 획득하기 위하여 이용하는 시간은 mode 3에서 mode보다 더 짧게 소요 되었다.(P=0.001). mode 2와 mode 3에서 1회기에서는 상관관계를 가지고 2-5회기 동안에는 mode 2와 mode 3에서 상관관계가 보이지 않았다(p = 0.012). mode 1의 환경에서는 훈련에 필요한 자기수용감각보다 시각적인 feedback에 의한 훈련이 진행되는 것을 볼 수 있다. mode 2는 첫 회기에서 자기수용감각에 의한 시각적인 feedback을 제공받을 수 있기 때문에 자기수용감각 훈련을 수행할 수 있다. 추후 연구는 시스템의 타당성 검증과 임상실험을 통한 훈련과 평가를 할 계획이다.

• Journal of Power Electronics
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• 제9권3호
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• pp.499-506
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• 2009

In this paper, the initial pole-position estimation of a surface (non-salient) permanent magnet synchronous motor is mathematically analyzed and surveyed on the basis of simulation analysis, and developed for accurate servo motor drive. This algorithm is well carried out under the full closed-loop position control without any pole sensors and is completely insensitive to any motor parameters. This estimation is based on the principle that the initial pole-position is simply calculated by the reverse trigonometric function using the two feedback currents in the full closed-loop position control. The proposed algorithm consists of the predefined reference position profile, the information of feedback currents, speed, and relative position, and the reverse trigonometric function for the initial-pole position estimation. Comparing with the existing researches, the mathematical analysis is introduced to get a more accurate initial pole-position of the surface permanent magnet motor under the closed-loop position control. It is found that the proposed algorithm can be easily applied in servo drive applications because it satisfies the following user's specifications; accuracy and moving distance.

• 대한물리의학회지
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• 제16권4호
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• pp.55-65
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• 2021

PURPOSE: This study compared the effects of sit-to-stand training with various foot positions combined with visual feedback on the postural alignment and balance. METHODS: Thirty stroke patients were assigned randomly into three groups of standing with a symmetrical foot position (SSF) (n = 10), asymmetrical foot position with the affected foot at the rear (SAF) (n = 10), and visual feedback and asymmetrical foot position (SVAF) (n = 10). Sit-to-stand training with different foot positions was performed for 30 minutes a day, five times a week, for a total of four weeks, and the effects on postural alignment and balance were assessed. RESULTS: The angle between the midline and scapula peak of the affected side was decreased significantly at sitting and thigh-off in the SAF group and at sitting, thigh-off, and standing in the SVAF group (p < .05). The angle between the midline and scapula peak of the non-affected side was increased significantly at sitting and thigh-off in the SAF group and at sitting, thigh-off, and standing in the SVAF group, the difference in the angle between the scapular peaks of the left and right sides was decreased significantly at sitting and thigh-off in SSF group, and at sitting in SAF group (p < .05). In the SVAF group, the angle at sitting, thigh-off, and standing was decreased significantly (p < .05). A comparison of the balance ability showed that BSS in the SVAF group was improved significantly (p < .05). CONCLUSION: Based on these results, the postural alignment and balance ability were improved in stroke patients who participated in sit-to-stand with visual feedback and asymmetrical foot position training.