• Title/Summary/Keyword: Precision Servo Control

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A Study on Precision Position Measurement Method for Analog Quadrature Encoder (정현파 엔코더를 이용한 정밀위치 측정방법에 관한 연구)

  • Kim Myong-Hwan;Kim Jang-Mok;Kim Cheul-U
    • The Transactions of the Korean Institute of Power Electronics
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    • v.9 no.5
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    • pp.485-490
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    • 2004
  • This paper presents a new interpolation algorithm for measuring high resolution position information which is prepared to a nino servo control motor using analog quadrature encoder. In the past, there are large capacity of memory(ROM or RAM) and two high price and resolution A/D(Analog-to-Digital Converter) for sensing two quadrature signals from a analog sinusoidal encoder interpolation. But high resolution of position from sinusoidal encoder can be obtained by using only small capacity of memory, one A/D converter and comparator. Experimental results show that the proposed algorithm is useful for measuring high resolution position.

Analysis of the Characteristics of the Feed motor Current for the Estimation of the Cutting Force in General Cutting Environment (일반적 상황에서 2차원 절삭력 추정을 위한 이송모터 전류의 거동분석)

  • Jeong, Young-Hun;Yun, Seong-Hyun;Cho, Dong-Woo
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.4
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    • pp.93-100
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    • 2002
  • The current from the feed motor of a machine tool contains substantial information about the machining state. There have been many researches that investigated the current as a measure for the cutting farces. However it has been reported that this indirect measurement of the cutting farces from the feed motor current is only feasible in low frequency. In this research, it was presented that the bandwidth of the current monitoring can be expanded to 130 Hz. And the unusual behavior of the current was examined in this bandwidth. The cross-feed directional cutting force influences the machined surface of the workpiece, which makes it necessary to estimate this force to control the roughness of the machined sulfate. The current exists in the stationary feed motor, and it can give the useful information on the quality of the machined surface. But the unpredictable behavior of the current prevents applying the current to prediction of the cutting state. Empirical approach was conducted to resolve the problem. As a result, the current was shown to be related to the accumulation of the accumulation of the infinitesimal rotation of the motor. rotation of the motor. Subsequently the relationship between the current and the cutting force was identified.

A New Current Control Algorithm for Torque Ripple Reduction of BLDC Motors (BLDC 전동기의 토크리플 저감을 위한 새로운 전류제어 알고리즘에 대한 연구)

  • 김태성;안성찬;현동석
    • The Transactions of the Korean Institute of Power Electronics
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    • v.6 no.5
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    • pp.416-422
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    • 2001
  • The BLDC(Brushless DC) Motor is characterized by linear torque to current and speed to voltage. It has low acoustic noise and fast dynamic response. Moreover, it has high power density with high proportion of torque to inertia in spite of small size drive. However, when armature current is commutated, the current ripple is generated by the motor inductance components in stator windings and back-EMF. This current ripple caused to torque ripple. Therefore, it is difficult to apply the BLDC motor to a precision servo drive system. In this paper, a new current control algorithm using fourier series coefficients is proposed. This proposed algorithm can minimize torque ripple due to the phase current commutation of BLDC motor. Simulation and Experimental results prove the effectiveness at the Proposed algorithm through comparison with the conventional unipolar PWM method.

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Development of a Controller for Variable-rate Application of Granular Fertilizer (입제 비료의 변량 살포를 위한 제어기 개발)

  • Yu J.H.;Kim Y.J.;Ryu K.H.
    • Journal of Biosystems Engineering
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    • v.31 no.2 s.115
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    • pp.108-114
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    • 2006
  • This study was conducted to design and fabricate a controller for variable-rate application of granular fertilizer based on physical and chemical information, to analyze the performance of the controller and characteristics of a discharger. The result of the study are summarized as follows: 1. The charge ratios of discharger by accumulation heights of fertilizer in hopper were examined, and the variations in charge ratio were $72.58{\sim}93.33%$ and $63.14{\sim}94.42%$ for the fertilizers Super 21 and Sinsedae, respectively. The charge ratio also decreased as the rotational speed of discharger increased. 2. The coefficient of variation of discharge amount by rotational speed and discharge time of discharger were in the range of $2.94{\sim}11.23%$ and $2.82{\sim}10.80%$ for the fertilizer of Super 21 and Sinsedae. Except the rotational speed of 12 rpm, the coefficient of variation for discharge amount were relatively small with 4% more or less 3. In order to evaluate the rotational speed of discharger, the control signal in the range of $0{\sim}5V$ was subdivided into the 50 steps by 0.1V. The regression equation for the rotational speed of discharger was Y=55.984X-79.174(X: input voltage, V, Y: discharger speed, RPM) and the $R^2$ was 0.99. 4. In order to evaluate the performance of the controller for variable-rate application of granular fertilizer, settling time to unit step input was examined. The settling time varied from 0.8sec to 1.4 sec.