• Title/Summary/Keyword: Positioning motion

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Enhancing Motion Capture Data (모션 캡쳐 데이터 향상 기법)

  • 최광진
    • Proceedings of the Korea Society for Simulation Conference
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    • 1998.10a
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    • pp.120-123
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    • 1998
  • In animating an articulated entity with motion capture data, especially when the reconstruction is based on forward kinematics, there could be large discrepancies at the end effector. The small errors in joint angles tend to be amplified as the forward kinematics positioning progresses toward the end effector. In this paper, we present an algorithm that enhances the motion capture data to reduce positional errors at the end effector. The process is optimized so that the characteristics of the original joint angle data is preserved in the resulting motion. The frames at which the end-effector position needs to be accurate are designated as“keyframes”(e.g. starting and ending frames). In the algorithm, corrections by inverse kinematics are performed at sparse keyframes and they are interpolated with a cubic spline which produces a curve best approximating the measured joint angles. The experiment proves that our algorithm is a valuable tool to improve measured motion especially when end-effector trajectory contains a special goal.

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Radio Frequency Based Emergency Exit Node Technology

  • Choi, Youngwoo;Kim, Dong Kyoo;Kang, Do Wook;Choi, Wan Sik
    • Journal of Positioning, Navigation, and Timing
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    • v.2 no.1
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    • pp.91-100
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    • 2013
  • This paper introduces an indoor sensor fusion wireless communication device which provides the Location Based Service (LBS) using fire prevention facility. The proposed system can provide information in real time by optimizing the hardware of Wi-Fi technology. The proposed system can be applied to a fire prevention facility (i.e., emergency exit) and provide information such as escape way, emergency exit location, and accident alarm to smart phone users, dedicated terminal holders, or other related organizations including guardians, which makes them respond instantly with lifesaving, emergency mobilization, etc. Also, the proposed system can be used as a composite fire detection sensor node with additional fire and motion detect sensors.

Global Stage of Reproducibility Experiment for Single Point Diamond Turning (초정밀 선삭가공을 위한 글로벌스테이지의 재현성 실험)

  • Park, Dae-Kwang;Kwak, Nam-Su;Kwon, Dae-Ju;Kim, Jae-Yeol
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.22 no.6
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    • pp.982-988
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    • 2013
  • With conventional positioning apparatus, it is very difficult to simultaneously achieve the desired driving range and precision at the sub-micrometer level. Generally, lead screw and friction drive, etc., have been used as servo control systems. These have large driving ranges, and high-speed positioning is feasible. In this study, we present a global servo system controlled by a laser interferometer acting as a displacement measurement sensor for achieving positioning accuracy at the sub-micrometer level.

Contact-free Linear Actuator Using Active Magnetic Bearing (능동 자기 베어링을 이용한 비접촉식 선형 구동기)

  • 이상헌;백윤수
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.7
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    • pp.91-98
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    • 2003
  • In the field of precision manufacturing demanding high positioning performance, the mechanical friction in positioning device deteriorates the quality of the product and increases the cost of production for positioning devices. Therefore, we propose a contract-free linear actuator using active magnetic bearing. The structure and operating principle of the proposed system are explained, and the magnetic forces are analyzed by magnetic circuit theory to design magnetic bearings and linear actuator. With the derived equation of motion, the stability is identified. Experimental results are presented to show the feasibility.

A Flexure Guided Planar Scanner for Scanning Probe Microscope ; Part 1 : Design and Analysis of Static and Dynamic Properties (주사 현미경용 평면 스캐너 Part 1 :설계 및 정 · 동특성 해석)

  • Lee, Dong-Yeon;Lee, Moo-Yeon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.6 s.99
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    • pp.667-673
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    • 2005
  • This paper shows a method for design of the nano-positioning planar scanner used in the scanning probe microscope. The planar scanner is composed of flexure guides, piezoelectric actuators and feedback sensors. In the design of flexure guides, the Castigliano's theorem was used to find the stiffness of the guide. The motion amplifying mechanism was used in the piezoelectric actuator to achieve a large travel range. We found theoretically the travel range of the total system and verified using the commercial FEM(finite element method) program. The maximum travel range of the planar scanner is above than 140 $\mu$m. The 3 axis positioning capability was verified by the mode analysis using the FEM program.

Improvement of the Accuracy of Short Baseline Acoustic Positioning System (단기선 (SBL) 음향위치 시스템의 정도 개선)

  • 박해훈;윤갑동
    • Journal of the Korean Institute of Navigation
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    • v.17 no.1
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    • pp.99-105
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    • 1993
  • Underwater acoustic positioning systems have been extensively used not only in surface position fixing but also in underwater position fixing. Recently, these systems have been applied in the field of installation and underwater inspection offshore platforms etc. But in these systems are included the fixing errors as results of a signal with noise and irregular motion of vessel by ocean waves. In this paper to improve the accuracy of the position fixing a Kalman filter is applied to the short baseline(SBL) acoustic positioning system. The optimal position obtained by the Kalman filter is compared with the raw position and it is confirmed that the former is more accurate than the latter.

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Design and Modeling of a 6-dof Stage for Ultra-Precision Positioning (초정밀 구동을 위한 6 자유도 스테이지의 설계와 모델링)

  • Moon, Jun-Hee;Park, Jong-Ho;Pahk, Heui-Jae
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.6
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    • pp.106-113
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    • 2009
  • A 6-DOF precision stage was developed based on parallel kinematics structure with flexure hinges to eliminate backlash, stick-slip and friction and to minimize parasitic motion coupled with motions in the other-axis directions. For the stage, lever linkage mechanism was devised to reduce the height of system for the enhancement of horizontal stiffness. Frequency response comparison between experimental results and mathematical model extracted from dynamics of the stage was performed to identify the system parameters such as spring constants and damping coefficients of actuation modules, which cannot be calculated accurately by analytic methods owing to their complicated structures. This newly developed precision stage and its identified model will be very useful for precision positioning and control because of its high accuracy and non-coupled movement.

A Study on the Positioning Accuracy and table Deflection by Load (하중에 의한 위치결정오차와 테이블 처짐에 관한 연구)

  • 전언찬
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.8 no.6
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    • pp.98-104
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    • 1999
  • As the accuracy of manufactured goods needed high accuracy processing has made the efficiency of NC and measurement technology development, the innovation of machine tools has influence the development of the semi-conductor and optical technology. The movement errors can be expressed in terms of yaw, roll an pitch etc. In the case of expanding the error range, static, dynamic and servo gain errors can be included. Machining center might have twenty-one movement errs including three types of joint errors. Those errors have been measured on the condition of just loading of standard table. Regarding these measuring methods, the mechanical compliance of the structure has not been considered. In this paper, therefor, the influences of the additional load on the positioning accuracy are investigated. The results and the techniques proposed in this study can be considered very effective and useful to compensate more correctly the positioning motion.

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A Piezo-driven Fine Manipulation System Based on Flexure Hinges for Manipulating Micro Parts (미세 부품 조작을 위한 탄성힌지 기반 압전소자 구동형 초정밀 머니플레이션 시스템)

  • Choi, Kee-Bong;Lee, Jae-Jong;Kim, Gee-Hong;Ko, Kuk-Won
    • Journal of Institute of Control, Robotics and Systems
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    • v.15 no.9
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    • pp.881-886
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    • 2009
  • This paper presents a manipulation system consisting of a coarse/fine XY positioning system and an out-of-plane manipulator. The object of the system is to conduct tine positioning and manipulation of micro parts. The fine stage and the out-of-plane manipulator have compliant mechanisms with flexure hinges, which are driven by stack-type piezoelectric elements. In the fine stage, the compliant mechanism plays the roles of motion guide and displacement amplification. The out-of-plane manipulator contains three piezo-driven compliant mechanisms for large working range and fine resolution. For large displacement, the compliant mechanism is implemented by a two-step displacement amplification mechanism. The compliant mechanisms are manufactured by wire electro-discharge machining for flexure hinges. Experiments demonstrate that the developed system is applicable to a fine positioning and fine manipulation of micro parts.

A Study on the Errors in the Free-Gyro Positioning and Directional System (자유자이로 위치 및 방위시스템의 오차에 관한 연구)

  • Jeong, Tae-Gweon
    • Journal of Navigation and Port Research
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    • v.37 no.4
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    • pp.329-335
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    • 2013
  • This paper is to develop the position error equations including the attitude errors, the errors of nadir and ship's heading, and the errors of ship's position in the free-gyro positioning and directional system. In doing so, the determination of ship's position by two free gyro vectors was discussed and the algorithmic design of the free-gyro positioning and directional system was introduced briefly. Next, the errors of transformation matrices of the gyro and body frames, i.e. attitude errors, were examined and the attitude equations were also derived. The perturbations of the errors of the nadir angle including ship's heading were investigated in each stage from the sensor of rate of motion of the spin axis to the nadir angle obtained. Finally, the perturbation error equations of ship's position used the nadir angles were derived in the form of a linear error model and the concept of FDOP was also suggested by using covariance of position error.