• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.4
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• pp.24-32
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• 2012

Of many approaches to reduce motion analysis errors, the compensation method of anatomical landmarks estimates the position of anatomical landmarks during motion. The method models the position of anatomical landmarks with joint angle or skin marker displacement using the data of the so-called dynamic calibration in which anatomical landmark positions are calibrated in ad hoc motions. Then the anatomical landmark positions are calibrated in target motions using the model. This study applies the compensation methods with joint angle and skin marker displacement to three lower extremity motions (walking, sit-to-stand/stand-to-sit, and step up/down) in ten healthy males and compares their performance. To compare the performance of the methods, two sets of kinematic variables were calculated using different two marker clusters, and the difference was obtained. Results showed that the compensation method with skin marker displacement had less differences by 30~60% compared to without compensation. And, it had significantly less difference in some kinematic variables (7 of 18) by 25~40% compared to the compensation method with joint angle. This study supports that compensation with skin marker displacement reduced the motion analysis STA errors more reliably than with joint angle in lower extremity motion analysis.

• The Journal of Korean Physical Therapy
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• v.13 no.2
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• pp.453-458
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• 2001

The aim of this study is to present the basic reference data of age and specific gait parameters for Parkinson's Disease Patients. The basic gait parameters were extracted from 5 patients, 5 men and 65 years of age using VICON 512 Motion Analyzer. The temporal gait parameters and kinematic parameters is data of Parkinson's Disease Patients. The results were as follows; 1. The cadence, velocity, stride length decreased and single limb support period, double limb support period increased than normal adult in the temporal parameters. 2. The mean angles of joint pelvic tilt and hip, knee, ankle joint decreased than normal adult at kinematic characteristics on sagittal plane. 3. The mean angles of joint pelvic tilt and hip, knee joint has no difference than normal adult at kinematic characteristics on coronal plane. 4. The mean angles of joint pelvic tilt, hip joint no difference and internal, external rotation in ankle joint significantly decreased than normal adult at kinematic characteristics on transverse plane.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.7
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• pp.1632-1642
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• 1994

The Stewart Platform is a six-degree-of-freedom in-parallel-actuated manipiulator mechanism. The kinematic behavior of parallel mechanisms shows inverse characteristics as compared that of serial mechanisms; i.e, the inverse kinematic problem of Stewart Platform is straightforward, but no closed form solution of the forward kinematic problem has been previously presented. Thus it is difficult to calculate the 6 DOF displacement of the platform from the measured lengths of the six actuators in real time. Here, a real-time estimation algorithm which solves the Stewart Platform kinematic problem is proposed and tested through computer simulations and experiments. The proposed algorithm shows stable convergence characteristics, no estimation errors in steady state and good estimation performance with higher sampling rate. In experiments it is shown that the estimation result is the same as that of simulation even in the presence of measurement noise.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.11
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• pp.2672-2679
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• 2000

In synthesizing and RSSS-SC mechanism that is the kinematic model of the McPherson strut suspension system in automobiles, the design equations for R-S, S-S and S-C dyads should be solved separately for a given set of prescribed positions. The number of prescribed positions that the RSSS-SC mechanism can be synthesized is up to three because of the S-C dyad. This limitation may cause unsatisfactory results in synthesized joint positions. This paper presents a kinematic synthesis method to place the joints of an RSSS-SC mechanism in desired boundaries by varying the prescribed positions of the mechanism within acceptable tolerances. The sensitivity analysis of the joint positions is used determine which displacement parameter should be altered to fulfill this task.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.25-30
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• 2006

This study is about an optimum design to improve the kinematic and compliance characteristics of a torsion-beam suspension system. The kinematic and compliance characteristics of an initial design of the suspension was obtained through a roll-mode analysis. The objective function was set to minimize within design constraints. The coordinates of the connecting point between the torsion-beam and the trailing arm were treated as design parameters. Since the torsion-beam suspension has large nonlinear effects due to kinematic and elastic motion, Genetic Algorithms were employed for the optimal design. The optimized results were verified through a double-lane change simulation using the full vehicle model.

• Korean Journal of Applied Biomechanics
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• v.31 no.1
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• pp.44-49
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• 2021

Objective: The purpose of this study was to analyze kinematic variables according to ground slope angle during golf putting. Method: 26 collegiate golfers (age: 22.54±2.15 kg, height: 174.64±6.07 cm, weight: 71.35±9.27 kg, handicap: 5.11±4.50) were participated, and 8 motion capture cameras (250 Hz), Nexus, and Kwon3DXP software were used to collect data. It was performed repeated measures ANOVA and Bonferroni adjustment. Alpha set at .05. Results: Body alignments were not significantly different at address. Putter head trajectory and loft angle were significantly different, and AP direction of acceleration of putter head was significantly different. However, ML and SI direction of acceleration of putter head were not significantly different. Conclusion: Therefore, it was identified that ground slope angle was affected the kinematic variables during putting, and it will be performed that correlation analysis between putting success rate and kinematic variables according to ground slope angle during golf putting.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.3
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• pp.48-54
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• 2012

This paper introduces the kinematic calibration method to improve the positioning accuracy of a parallel mechanism. Since all the actuators in the parallel mechanism are controlled simultaneously toward the target position, the volumetric errors originated from each motion element are too complicated. Therefore, the exact evaluation of the error sources of each motion element and its calibration is very important in terms of volumetric errors. In the calibration processes, the measurement of the errors between commands and trajectories is necessary in advance. To do this, a digitizer was used for the data acquisition in 3 dimensional space rather than arbitrary planar error data. After that, the optimization process that was used for reducing the motion errors were followed. Consequently, Levenberg-Marquart algorithm as well as the error data acquisition method turned out effective for the purpose of the calibration of the parallel mechanism.

• Journal of Mechanical Science and Technology
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• v.17 no.12
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• pp.1977-1985
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• 2003

In the present study, the dynamic modelling of planar mechanisms that consist of a system of rigid bodies is carried out using point coordiantes. The system of rigid bodies is replaced by a dynamically equivalent constrained system of particles. Then for the resulting equivalent system of particles, the concepts of linear and angular momentums are used to generate the equations of motion without either introducing any rotational coordinates or distributing the external forces and force couples over the particles. For the open loop case, the equations of motion are generated recursively along the open chains. For the closed loop case, the system is transformed to open loops by cutting suitable kinematic joints with the addition of cut-joints kinematic constraints. An example of a multi-branch closed-loop system is chosen to demonstrate the generality and simplicity of the proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.269-272
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• 1987

This paper is concerned on kinematic analysis and simulation of an automatic feeding mechanism subjected by the motion of a curvilinear inverse cam. The main objection is the development of computer-aided design (CAD) program for simulating the motion of the cam-feeding mechanism using computer-graphics. A computer program CACAFS (Computer-Aided Cam and Automatic Feeding System) is independent of computer hardware used. The program is also interactive using a menu-selection technique. As the second part of the paper for the motion simulation of the cam-feeding system, this paper discusses the state-of-art for CAD. The first part of the paper presents the algorithm to simulate the notion of the cam-feeding mechanism.

• The Journal of Korea Robotics Society
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• v.5 no.3
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• pp.216-223
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• 2010

Most lamp units at ceilings, walls, and streets are static and no automatic motion capabilities are available at all to adjust lamp tilting angles and its zooming position. This paper proposes a new robotic lamp that creates three degrees of freedom (DOF) motion by using a spherical-type parallel mechanism with a unique forward kinematic position. In the robotic lamp, three motors are placed at the base frame to control two tilting angles and one zoom in-and-out motion for a localized light. The kinematic model of this device is derived and the proto type has been developed. The performance of this device was verified through experiment.