• Title/Summary/Keyword: Servo Filter

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KSR-III 김발엔진 구동장치 서보필터 설계

  • Sun, Byung-Chan;Jung, Ho-Lac
    • Aerospace Engineering and Technology
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    • v.1 no.2
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    • pp.105-112
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    • 2002
  • In this paper, a servo filter design for the gimbal engine actuator system of KSR-III(Korea Sounding Rocket-III) is considered. A reasonable filter structure is determined based on the actuator analytic models. The servo filter consists of a 2-nd order lowpass filter and a 1-st order compensator. The lowpass filter is required to protect the actuator from high frequency vibration, and the compensator to enhance the resulting stability. A Butterworth type servo filter is considered as the simplest one. The final servo filter type is determined by evaluating simultaneously both high frequency gain reduction performance and the corresponding KSR-III stability margin. Consequently it is revealed that a notch type servo filter located on the error between command signal and feedback signal in the control loop is very effective. Later, based on the proposed servo filter type, an onboard servo filter hardware of KSR-III will be designed and tested.

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Servo Filter Design for KSR-III Gimbal Actuation System (KSR-III 김발엔진 구동장치 서보필터 설계)

  • Sun, Byung-Chan;Park, Yong-Kyu;Choi, Hyung-Don
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.32 no.10
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    • pp.83-92
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    • 2004
  • This paper concerns servo filter design for KSR-III gimbal engine actuation system. When the actuator system is attached to engine mount frame, unexpected resonant modes in low frequency can occur and make the control system unstable. In order to prevent the resonance in the actuation system, a proper lowpass servo filter is designed. Based on the dynamic test data including the resonant effect, the shape of the servo filter is determined, and then the corresponding parameters are optimally designed. The best solution is finally selected via dynamic tests including the servo filter.

Ultra Precision Positining System for Servo Motor-piezo Actuator Using the Dual Servo Loop and Digital Filter Implementation (이중서보제어루프와 디지털 필터를 통한 서보모터-업전구동기의 초정밀위치결정 시스템 개발)

  • Lee, Dong-Sung;Park, Jong-Ho;Park, Heui-Jae
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.3 s.96
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    • pp.154-163
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    • 1999
  • In this paper, an ultra precision positioning system has been developed using dual servo loop control. For positioning system having long distance with ultra precision , the combination of global stage and micro stage was required. A servo motor based ball screw is used as a global stage and the piezo actuator as a micro stage. For the improvement of positional precision, the digital Chebyshev filter is implemented in the developed to dual servo system. Therefore, the positional repeatability has been achieved within ${\pm}$ 10 mm, and this technique can be applied to develop precision semiconductor equipments such as lithography steppers and probers.

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A Double Bi-Quad Filter with Wide-Band Resonance Suppression for Servo Systems

  • Luo, Xin;Shen, Anwen;Mao, Renchao
    • Journal of Power Electronics
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    • v.15 no.5
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    • pp.1409-1420
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    • 2015
  • In this paper, an algorithm using two bi-quad filters to suppress the wide-band resonance for PMSM servo systems is proposed. This algorithm is based on the double bi-quad filters structure, so it is named, "double bi-quad filter." The conventional single bi-quad filter method cannot suppress unexpected mechanical terms, which may lead to oscillations on the load side. A double bi-quad filter structure, which can cancel the effects of compliant coupling and suppress wide-band resonance, is realized by inserting a virtual filter after the motor speed output. In practical implementation, the proposed control structure is composed of two bi-quad filters on both the forward and feedback paths of the speed control loop. Both of them collectively complete the wide-band resonance suppression, and the filter on the feedback path can solve the oscillation on the load side. Meanwhile, with this approach, in certain cases, the servo system can be more robust than with the single bi-quad filter method. A step by step design procedure is provided for the proposed algorithm. Finally, its advantages are verified by theoretical analysis and experimental results.

Adaptive Suppression of Mechanical Resonance in High-Density Disk Drives (고밀도 디스크 드라이브의 적응형 공진 보상 알고리즘)

  • 강창익;김창환
    • Journal of Institute of Control, Robotics and Systems
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    • v.9 no.9
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    • pp.679-691
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    • 2003
  • The band-width of disk drive servo system is rapidly increasing for the robustness to external disturbance as the track density is increasing. The increase of the band-width may cause mechanical resonance of an actuator. In disk drive servo system, a notch filter is usually used to suppress the mechanical resonance of the actuator. However, the resonance frequency differs from drive to drive because of manufacturing tolerance and varies with temperature even within a single drive. The variation of resonance frequency degrades the suppression performance of the notch filter. In this paper, we present an adaptive digital notch filter that identifies the resonance frequency of the disk drive servo actutaor precisely and adjusts automatically its center frequency. For this, we design an adaptive FIR digital filter for the estimation of the resonance frequency. The estimation filter identifies the resonance frequency adaptively using the output signal generated from the servo system, which is excited with an excitation signal including all the expected resonance frequency components. We prove mathematically the convergence of the resonance frequency estimation filter. Furthermore, in order to demonstrate the practical use of our work, we present some experimental results using a commercially available disk drive.

The State Estimator Design for Servo system with Delayed Input (지연 입력을 가진 서보시스템의 상태 추정자 설계)

  • Shin, Doo-Jin;Kong, Jeong-Ja;Huh, Uk-Youl
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.5
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    • pp.607-614
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    • 1999
  • This paper deals with the design problem of the state estimator for servo system. The servo system has input time delay which depends on the computational time of control algorithm. The delayed input is a factor that brings out the state estimation error. So in order to reduce the state estimation error of the system, we propose a state estimator in which the delayed input of the system is considered. For this purpose, discrete time state space model is established accounting for the delayed input and a state estimator is designed based on this model. Kalman filter algorithm is employed in the design of the state estimator. The proposed estimator is used in the speed control of servo system with delayed input. Performance of the proposed state estimator is exemplified via simulations and experiments for servo system. Also, robustness of the proposed estimator to modeling error by variation of the system parameters is also shown in simulations.

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A High Performance Permanent Magnet Synchronous Motor Servo System Using Predictive Functional Control and Kalman Filter

  • Wang, Shuang;Zhu, Wenju;Shi, Jian;Ji, Hua;Huang, Surong
    • Journal of Power Electronics
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    • v.15 no.6
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    • pp.1547-1558
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    • 2015
  • A predictive functional control (PFC) scheme for permanent magnet synchronous motor (PMSM) servo systems is proposed in this paper. The PFC-based method is first introduced in the control design of speed loop. Since the accuracy of the PFC model is influenced by external disturbances and speed detection quantization errors of the low distinguishability optical encoder in servo systems, it is noted that the standard PFC method does not achieve satisfactory results in the presence of strong disturbances. This paper adopted the Kalman filter to observe the load torque, the rotor position and the rotor angular velocity under the condition of a limited precision encoder. The observations are then fed back into PFC model to rebuild it when considering the influence of perturbation. Therefore, an improved PFC method, called the PFC+Kalman filter method, is presented, and a high performance PMSM servo system was achieved. The validity of the proposed controller was tested via experiments. Excellent results were obtained with respect to the speed trajectory tracking, stability, and disturbance rejection.

Kalman Filter Estimation of the Servo Valve Effective Orifice Area for a Auxiliary Power Unit (보조 동력장치용 서보밸브 유효 오리피스 면적의 칼만필터 추정)

  • Zhang, J.F.;Kim, C.T.;Jeong, H.S.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.4 no.4
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    • pp.1-7
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    • 2007
  • Flow rate is one of the important variables for precise motion control and detection of the faults and fluid loss in many hydraulic components and systems. But in many cases, it is not easy to measure it directly. The orifice area of a servo valve by which the fluid flows is one of key factors to monitor the flow rate. In this paper, we have constructed an estimation algorithm for the effective orifice area by using the model of a servo valve cylinder control system and Kalman filter algorithm. Without geometry information about the servo valve, it is shown that the effective orifice area can be estimated by using only displacement and pressure data corrupted with noise. And the effect of the biased sensor data and system parameter errors on the estimation results are discussed. The paper reveals that sensor calibration is important in accurate estimation and plausible parameter data such as oil bulk modulus and actuator volume are acceptable for the estimation without any error. The estimation algorithm can be used as an useful tool for detecting leakage, monitoring malfunction and/or degradation of the system performance.

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Design of an Estimator for Servo Systems using Discrete Kalman Filter (이산형 칼만 필터를 이용한 서보 시스템의 추정자 설계)

  • Shin, Doo-Jin;Huh, Uk-Youl
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.8
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    • pp.996-1003
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    • 1999
  • This paper propose a position-speed controller with an estimator which can estimate states and disturbance. The overall control system consists of two parts: the position-speed controller and an estimator. The Kalman filter applied as state-feedback controller is an optimal state estimator applied to a dynamic system that involves random perturbations and gives a linear, unbiased and minimum error variance recursive algorithm to optimally estimate the unknown state. Therefore, we consider the error problem about the servo system modeling and the measurement noise as a stochastic system and implement a optimal state observer, and enhance the estimate performance of position and speed using that. Using two-degree-of freedom(TDOF) conception, we design the command input response and the closed loop characteristics independently. The servo system is to improve the closed loop characteristics without affecting the command imput response. The characteristics of the closed loop system is improved by suppressing disturbance torque effectively with the disturbance observer using a inverse-transfer matrix. Therefore, the performance of overall position-speed controller is enhanced. Finally, the performance of the proposed controller is exemplified by some simulations and by applying the real servo system.

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Indirect Cutting Force Measurement in Milling Process using Kalman Filter by Sensing Servo motor Current (카만필터와 이송모터의 전류 감지를 이용한 밀링공정시의 설삭력 간접측정)

  • 김종원;김태용;이원희
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1994.10a
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    • pp.3-8
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    • 1994
  • This paper presents a practical method of measuring the cutting force milling process by sensing the feed-drive servo motor current,avoiding the use of a dynamomenter. The relation between the cutting force and the servo motor currents is obtained after the feed-drive system of machining center is modelled. In order to measure the cutting force indirectly, the cutting force in the feed-drive system is regrared as a disturbance, and a disturbance estimator is designed using Kalman filter. A horizontal type machining center is used in the experimental study. A comparison is made between the cutting force measured from the dynamometer and the servo motor current.

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