• Title, Summary, Keyword: Motor Point

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Effect of rotor slip on the gear ratio of wobble motor (회전자 슬립이 wobble 모터의 기어비에 미치는 영향)

  • Yun, Seo-Jin;Lee, Eun-Woong;Woo, Sung-Bong
    • Proceedings of the KIEE Conference
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    • pp.339-341
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    • 1999
  • This paper presents the gear ratio of wobble motor, accounting for finite friction in contact point. The gear ratio of a wobble motor is affected by rotor slip, which is a function of motive torque, excitation angle, and friction torque. The gear ratio of a wobble motor can be expressed as a constant term plus a term that accounts for rotor slip. The ideal gear ratio is constant term and is equal to the rotor radius divided by the distance between the center of the rotor and the center of the stator. The rotor-slip term is shown to be directly proportional to the contact point friction torque and inversely proportional to the square of the excitation voltage.

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Nanometric Positioning Over a One-Millimeter Stroke Using a Flexure Guide and Electromagnetic Linear Motor

  • Fukada, Shigeo;Nishimura, Kentaro
    • International Journal of Precision Engineering and Manufacturing
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    • v.8 no.2
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    • pp.49-53
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    • 2007
  • In this study, we investigated experimentally the potential of a planer positioning mechanism with three degrees of freedom using a flexure guide and an electromagnetic linear motor. The goal was to produce a multi-axis positioning system with nanometric resolution over a 1-mm stroke. An $X-Y-\theta$ stage was designed based on previous results from a single-axis prototype and was constructed with a flexure guide mechanism and voice coil motor type linear actuators. We examined the necessity of a driving method and control system to ensure high resolution for multi-axis positioning. Experiments were conducted to evaluate the performance, and the results confirmed the mechanism's potential; fine point-to-point (PTP) positioning was achieved over a 1-mm stroke, with a resolution of 2 nm for translation in X-Y and 0.01 asec for yaw in $\theta$.

Underlying Control Strategy of Human Leg Posture and Movement

  • Park, Shinsuk
    • Journal of Mechanical Science and Technology
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    • v.18 no.4
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    • pp.649-663
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    • 2004
  • While a great number of studies on human motor control have provided a wide variety of viewpoints concerning the strategy of the central nervous system (CNS) in controlling limb movement, none were able to reveal the exact methods how the movement command from CNS is mapped onto the neuromuscular activity. As a preliminary study of human-machine interface design, the characteristics of human leg motion and its underlying motor control scheme are studied through experiments and simulations in this paper. The findings in this study suggest a simple open-loop motor control scheme in leg motion. As a possible candidate, an equilibrium point control model appears consistent in recreating the experimental data in numerical simulations. Based on the general leg motion analysis, the braking motion by the driver's leg is modeled.

Design of Air Gap for Reducing Torque Ripple in a Single-Phase BLDC Motor (단상 BLDC 전동기의 토오크 리플 저감을 위한 공극 설계)

  • Yang, Byeong-Ryeol;Gwon, Byeong-Il;Park, Seung-Chan
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.51 no.2
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    • pp.49-54
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    • 2002
  • Most single-Phase brushless DC (BLDC) motors have unequal air gap to eliminate the dead-point where the developed torque value is zero. However this partial increase of the air gap deteriorates the motor characteristics in cogging torque. Thus in this paper a new topology of unequal air gap is proposed to solve this problem. The topology is to use some pairs of equal or unequal air gaps. As a result, it is proved by the finite element analysis and experimental results that the single-Phase BLDC motor with the proposed air gap topology is very effective in reducing the cogging torque.

Design of Shaking Beam for Piezoelectric Linear Ultrasonic Motor

  • Yoon, Seok-Jin;Park, Ji-Won;Kim, Sang-Jong;Yu, Yeon-Tae;Kim, Hyun-Jai
    • Journal of the Korean Ceramic Society
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    • v.40 no.11
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    • pp.1062-1066
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    • 2003
  • Design of a piezoelectric actuator for the ultrasonic motor must ensure that contact point has elliptic trajectory of movement. The new idea of an elliptic trajectory formation of the piezoelectric actuator is investigated in the paper. Shaking beam for the piezoelectric linear ultrasonic motor was introduced to realize this new idea. The principle is based on the excitation of longitudinal and flexural vibrations of the actuator by using two sources of longitudinal mechanical vibrations shifted by $\pi$/2. Mode-frequency and harmonic response analyses of the actuator based on FEM have been carried out. The moving trajectory of the contact point has been defined. Finally, The experimental research of shaking beam has been confirmed an opportunity of the elliptic trajectory reception with the help of one stable mode of the vibrations.

A study on the improvement of floating point operation for AC servo motor controller based on fixed point DSP (고정소수연산 DSP 기반 AC 서보모터 제어기의 소수연산 개선에 관한 연구)

  • Hwang In-Sung;Choi Chi-Young;Hong Sun-Ki
    • Proceedings of the KIEE Conference
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    • pp.1196-1198
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    • 2004
  • This paper represents the improvement of floating point operation for AC servo motor controller based on fixed point operation DSP. TMS320F2812 has fixed point operation processing structure. The controller parameters are modified to the digitized data by scaling the original parameters. TMS320F 2812 is a 32-bit processor, and it could have enough accuracy to got the digitized data this procedure is implemented and the experiments controling a AC servo system.

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A study on the improvement of floating point operation for AC servo motor controller based on fixed point DSP (고정소수연산 DSP 기반 AC 서보모터 제어기의 소수연산 개선에 관한 연구)

  • Hwang, In-Sung;Hong, Sun-Ki
    • Proceedings of the KIEE Conference
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    • pp.43-45
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    • 2004
  • This paper represents the improvement of floating point operation for AC servo motor controller based on fixed point operation DSP. TMS320F2812 has fixed point operation processing structure. The controller parameters are modified to the digitized data by scaling the original parameters. TMS320F 2812 is a 32-bit processor, and it could have enough accuracy to get the digitized data this procedure is implemented and the experiments controling a AC servo system.

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A study about rotor position estimation enhance using IQ math in DSP (DSP 내의 IQ math를 이용한 회전자 위치 추정 정밀도 향상에 관한 연구)

  • Jang, Joong-Hack;Lee, Kwang-Ho;Hong, Sun-Ki
    • Proceedings of the KIEE Conference
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    • pp.98-100
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    • 2005
  • DSPs used at motor control are usually fixed point processor. They need scaling because they cannot excute floating point calculation. Scaling for floating point calculation makes the DSP's speed down, complex coding and etc. Therefore the IQ math is adopted. IQ math makes the fixed point processor possible to calculate the floating point math. In addition, IQ math can reduce memory usage and be more faster than that without IQ math. It seems that IQ math is appropriate in motor position control. In comparison of the position calculation between the IQ math, math function and the sine table, the method using IQ math is superior than other methods.

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The Effect on Activity of Cerebral Cortex by Key-point Control of The Adult Hemiplegia with fMRI (fMRI를 이용한 성인 편마비의 항조절점 운동이 대뇌피질의 활성화에 미치는 효과)

  • Lee Won-Kil
    • The Journal of Korean Physical Therapy
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    • v.15 no.3
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    • pp.295-345
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    • 2003
  • This study investigated activation of cerebral cortex in patients with hemiplegia that was caused by neural damage. Key-point control movement therapy of Bobath was performed for 9 weeks in 3 subjects with hemiplegia and fMRI was used to compare and analyze activated degree of cerebral cortex in these subjects. fMRI was conducted using the blood oxygen level-dependent(BOLD) technique at 3.0T MR scanner with a standard head coil. The motor activation task consisted of finger flexion-extension exercise in six cycles(one half-cycles = 8 scans = $3\;sec{\times}\;8\;=\;24\;sec$). Subjects performed this task according to visual stimulus that sign of right hand or left hand twinkled(500ms on, 500ms off). After mapping activation of cerebral motor cortex on hand motor function, below results were obtained. 1. Activation decreased in primary motor area, whereas it increased in supplementary motor area and visual association area(p<.001). 2. Activation was observed in bilateral medial frontal gyrus, middle frontal gyrus of left cerebrum, inferior frontal gyrus, inter-hemispheric, fusiform gyrus of right cerebrum, superior parietal lobule of parietal lobe and precuneus in subjedt 1, parahippocampal gyrus of limbic lobe and cingulate gyrus in subject 2, and inferior frontal gyrus of right frontal lobe, middle frontal gyrus, and inferior parietal lobule of left cerebrum in subject 3 (p<.001). 3. Activation cluster extended in declive of right cellebellum posterior lobe in subject 1, culmen of anterior lobe and declive of posterior lobe in subject 2, and dentate gyrus of anterior lobe, culmen and tuber of posterior lobe in subject 3 (p<.001). In conclusion, these data showed that Key-point control movement therapy of Bobath after stroke affect cerebral cortex activation by increasing efficiency of cortical networks. Therefore mapping of brain neural network activation is useful for plasticity and reorganization of cerebral cortex and cortico-spinal tract of motor recovery mechanisms after stroke.

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Validation of the Simplified Motor Score for the Triage after Traumatic Brain Injury (두부 외상 환자의 중증도 평가 시 단순운동점수의 유용성)

  • Lee, Sang Kyong;Ryoo, Hyun Wook;Park, Jung Bae;Seo, Kang Suk;Chung, Jae Myung
    • Journal of Trauma and Injury
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    • v.21 no.2
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    • pp.71-77
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    • 2008
  • Purpose: The Glasgow Coma Scale (GCS), though it is widely used for triage, has been criticized as being unnecessarily complex. Recently, a 3-point Simplified Motor Score (SMS, defined as obeys commands=2; localizes pain=1; withdrawals to pain or worse=0) was developed from the motor component of the GCS and was found to have a similar test performance for triage after traumatic brain injury when compared with the GCS as the criterion standard. The purpose of this study was to validate the SMS. Methods: We analyzed the patients who visited Kyungpook National University Hospital emergency center after traumatic brain injury from 2006 January to 2006 June. The test performance of the GCS, its motor component, and SMS relative to three clinically relevant traumatic brain injury outcomes (abnormal brain CT scans, Abbreviated Injury Scale $(AIS){\geq}4$, and mortality) were evaluated with areas under the receiver operating characteristic curves (AUCs). Results: Of 504 patients included in the analysis, 25.6% had an abnormal brain CT scans, 13.1% had $AIS{\geq}4$, and 5.0% died. The AUCs for the GCS, its motor component, and SMS with respect to the abnormal CT scans were 0.776, 0.715, and 0.716, and respectively, those for $AIS{\geq}4$ and mortality, were 0.969, 0.973, and 0.968, and 0.931, 0.909, and 0.909, respectively. Conclusion: The 3-point SMS demonstrated similar test performance when compared with the 15-point GCS score and its motor component for triage after traumatic brain injury in our populations.