• Title/Summary/Keyword: Observer algorithm

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Comparison of Control Performance according to the Injection Voltage Waveform of the Harmonic Voltage Injection Sensorless Technique (주입 전압파형의 형상에 따른 고조파 주입 센서리스 기법의 제어 성능 비교)

  • Moon, Kyeong-Rok;Lee, Dong-Myung
    • Journal of IKEEE
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    • v.26 no.1
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    • pp.43-49
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    • 2022
  • This paper compares the sensorless control performance according to the applied voltage waveform by injecting sinusoidal, triangular, and square waveform in the harmonic injection sensorless control method. By injecting various voltage shape waveform with a frequency of 1kHz, the error amount of the estimated angle for each waveform is compared and analyzed. For the experiment, the HILS(hardware in the loop simulation) system was used. The hardware is the control board, and the inverter and motor models implemented in Simulik are located in the real-time simulator. The control algorithm is implemented by the FPGA control board, which includes a PWM interrupt service routine with a frequency of 10 kHz, harmonic injection and position detection sensorless algorithm.

Objective and Quantitative Evaluation of Image Quality Using Fuzzy Integral: Phantom Study (퍼지적분을 이용한 영상품질의 객관적이고 정량적 평가: 팬톰 연구)

  • Kim, Sung-Hyun;Suh, Tae-Suk;Choe, Bo-Young;Lee, Hyoung-Koo
    • Progress in Medical Physics
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    • v.19 no.4
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    • pp.201-208
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    • 2008
  • Physical evaluations provide the basis for an objective and quantitative analysis of the image quality. Nonetheless, there are limitations in using physical evaluations to judge the utility of the image quality if the observer's subjectivity plays a key role despite its imprecise and variable nature. This study proposes a new method for objective and quantitative evaluation of image quality to compensate for the demerits of both physical and subjective image quality and combine the merits of them. The images of chest phantom were acquired from four digital radiography systems on clinic sites. The physical image quality was derived from an image analysis algorithm in terms of the contrast-to-noise ratio (CNR) of the low-contrast objects in three regions (lung, heart, and diaphragm) of a digital chest phantom radiograph. For image analysis, various image processing techniques were used such as segmentation, and registration, etc. The subjective image quality was assessed by the ability of the human observer to detect low-contrast objects. Fuzzy integral was used to integrate them. The findings of this study showed that the physical evaluation did not agree with the subjective evaluation. The system with the better performance in physical measurement showed the worse result in subjective evaluation compared to the other system. The proposed protocol is an integral evaluation method of image quality, which includes the properties of both physical and subjective measurement. It may be used as a useful tool in image evaluation of various modalities.

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A New Integral Variable Structure Regulation Controller for Robot Manipulators with Accurately Predetermined Output Performance (로봇 매니플레이터를 위한 정확한 사전 결정 출력 성능을 갖는 새로운 적분 가변구조 레귤레이션 제어기)

  • Lee, Jung-Hoon
    • Journal of IKEEE
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    • v.8 no.1 s.14
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    • pp.96-107
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    • 2004
  • In this paper, a new integral variable structure regulation controller(IVSRC) is designed by using a special integral sliding surface and a disturbance observer for the improved regulation control of highly nonlinear robot manipulators with prescribed output performance. The sliding surface having the integral state with a special initial condition is employed in this paper to exactly predetermine the ideal sliding trajectory from a given initial condition to origin without any reaching phase. And a continuous sliding mode input using the disturbance observer is also introduced in oder to effectively follow the predetermined sliding trajectory within the prescribed accuracy without large computation burden. The performance of the prescribed tracking accuracy to the predetermined sliding trajectory is clearly investigated in detail through the two theorems together with the closed loop stability. The design of the proposed IVSRC is separated into the performance design and robustness design in each independent link. The usefulness of the algorithm has been demonstrated through simulation studies on the regulation control of a two link manipulator under parameter uncertainties and payload variations, in view of no reaching phase, no overshoot, predetermined response with prescribed accuracy, easy change of output performance, separation of design phase, and so on.

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Development of Digital 3D Real Object Duplication System and Process Technology (디지털 3차원 실물복제기 시스템 및 공정기술 개발)

  • Kim D.S.;An Y.J.;Lee W.H.;Choi B.O.;Chang M.H.;Baek Y.J.;Choi K.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.732-737
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    • 2005
  • Distal 3D Real Object Duplication System(RODS) consists of 3D Scanner and Solid Freeform Fabrication System(SFFS). It is a device to make three-dimensional objects directly from the drawing or the scanning data. In this research, we developed an office type SFFS based on Three Dimensional Printing Process and a industrial SFFS using Dual Laser. An office type SFFS applied sliding mode control with sliding perturbation observer(SMCSPO) algorithm for control of this system. And we measured process variables about droplet diameter measurement and powder bed formation etc. through experiments. Also, in order to develop more elaborate and speedy system for large objects than existing SLS process, this study applies a new Selective Multi-Laser Sintering(SMLS) process and 3-axis dynamic Focusing Scanner for scanning large area instead of the existing $f\theta$ lens. In this process, the temperature has a great influence on sintering of the polymer. Also the laser parameters are considered like that laser beam power, scan speed, scan spacing. Now, this study is in progress to eveluate the effect of experimental parameters on the sintering process.

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A High-Performance Position Sensorless Motion Control System of Reluctance Synchronous Motor with Direct Torque Control (직접토크제어에 의한 위치검출기 없는 릴럭턴스 동기전동기의 위치 제어시스템)

  • 김동희;김민회;김남훈;배원식
    • The Transactions of the Korean Institute of Power Electronics
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    • v.7 no.5
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    • pp.427-436
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    • 2002
  • This paper presents an implementation of high-dynamic performance of position sensorless motion control system of Reluctance Synchronous Motor(RSM) drives for an industrial servo system with direct torque control(DTC). The problems of high-dynamic performance and maximum efficiency RSM drives controlled by DTC are saturation of stator linkage flux and nonlinear inductance characteristics with various load currents. The accurate estimation of the stator flux and torque are obtained using stator flux observer of which a saturated inductance $L_d$ and $L_q$ can be compensated by adapting from measurable the modulus of the stator current and rotor position. To obtain fast torque response and maximum torque/current with varying load current, the reference command flux is ensured by imposing $I_{ds} = I_{qs}$. This control strategy is proposed to achieve fast response and optimal efficiency for RSM drive. In order to prove rightness of the suggested control algorithm, the actual experiment carried out at $\pm$20 and $\pm$1500 rpm. The developed digitally high-performance motion control system shown good response characteristic of control results and high performance features using 1.0kW RSM which has 2.57 Ld/Lq salient ratio.

A Study on the Design of the Optimal Control System for Electric Driving Digital Governor (전기구동방식 디지털 가버너의 최적제어계 설계에 관한 연구)

  • Kim, Seong-Hwan;Ra, Jin-Hong;Yang, Ju-Ho
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.26 no.1
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    • pp.88-100
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    • 1990
  • Since sea state changes engine load instantaneously, the speed governing apparatus is essential for marine engine to maintain constant speed regardless of the load. As governing apparatuses, mechanical, pneumatic, and electric governors have been employed. But, recently, according to the introduction of low speed-ling stroke engines to increase thermal efficiency, the development of governor which has better response characteristics is requisite. In this paper, to design the governor that meets above requirement, author made a performance test for the existing PID control digital governor with the aid of computer simulation, and investigated digital governor applying the optimal control algorithm, then, executed computer simulation by the same way. As the result of simulations, found that the former let engine have large overshoot and long settling time at low speed, on the other hand, the latter made engine have better response. If we design and invent a good observer for delay time element so that the optimal control theory can be applied, better governor will be expected.

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Visualization of The Three Dimensional Information Using Stereo Camera (스테레오 카메라를 이용한 3차원 정보의 가시화)

  • Lee, Nam-Oh;Park, Soon-Yong;Lee, Seung-Min
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.47 no.4
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    • pp.15-20
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    • 2010
  • The three dimensional information is extracted and visualized using by stereo images of the object and the method for a 3D stereoscopic image is presented by the vergence control algorithm. The matching, which is applied a undistortion of lens and the energy function, is executed for the efficient extraction three dimensional information. Especially, applying the optimized method of matched line to the multi direction of the disparity imges. The disadvantages of multi directional method and reliability expansion method is collected. The matched interesting range of the three dimensional information is visualized using by VRML and more 3D stereoscopic image is visualized through the vergence control according to distance of the object. more improved three dimensional information is provided to observer by visualizing both of them at the same time.

Gaze Detection System by IR-LED based Camera (적외선 조명 카메라를 이용한 시선 위치 추적 시스템)

  • 박강령
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.4C
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    • pp.494-504
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    • 2004
  • The researches about gaze detection have been much developed with many applications. Most previous researches only rely on image processing algorithm, so they take much processing time and have many constraints. In our work, we implement it with a computer vision system setting a IR-LED based single camera. To detect the gaze position, we locate facial features, which is effectively performed with IR-LED based camera and SVM(Support Vector Machine). When a user gazes at a position of monitor, we can compute the 3D positions of those features based on 3D rotation and translation estimation and affine transform. Finally, the gaze position by the facial movements is computed from the normal vector of the plane determined by those computed 3D positions of features. In addition, we use a trained neural network to detect the gaze position by eye's movement. As experimental results, we can obtain the facial and eye gaze position on a monitor and the gaze position accuracy between the computed positions and the real ones is about 4.2 cm of RMS error.

A Rotor Position Estimation of Brushless DC Motors using Neutral Voltage Compensation Method (중성점전압보상 방식을 이용한 브러시리스직류전동기의 회전자위치 추정)

  • Song Joong-Ho
    • The Transactions of the Korean Institute of Power Electronics
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    • v.9 no.5
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    • pp.491-497
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    • 2004
  • This paper presents a new rotor position estimation method for brushless DC motors. It is clear that the estimation error of the rotor position provokes the phase shift angle misaligned between the phase current and the back-EMF waveforms, which causes torque ripple in brushless DC motor drives. Such an estimation error can be reduced with the help of the proposed neutral voltage-based estimation method that is structured in the form of a closed loop observer. A neutral voltage appearing during the normal mode of the inverter operation is found to be an observable and controllable measure, which can be dealt with for estimating an exact rotor position. This neutral voltage is obtained from the DC-link current, the switching logic, and the motor speed values. The proposed algorithm, which can be implemented easily by using a single DC-link current and the motor terminal voltage sensors, is verified by simulation and experiment results.

Correction on Current Measurement Errors for Accurate Flux Estimation of AC Drives at Low Stator Frequency (저속영역에서 교류전동기의 정확한 자속추정을 위한 전류측정오차 보상)

  • Cho, Kyung-Rae;Seok, Jul-Ki
    • The Transactions of the Korean Institute of Power Electronics
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    • v.12 no.1
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    • pp.65-73
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    • 2007
  • This paper presents an on-line correction method of current measurement errors for a pure-integration-based flux estimation down to 1-Hz stator frequency. An observer-based approach is taken as one possible solution of eliminating the dc offset and the negative sequence component of unbalanced gains in the synchronous coordinate. At the same time, the positive sequence component estimation is performed by creating an error signal between a motor model reference and an estimated q-axis rotor flux established by a permanent magnet (PM) in the synchronous coordinate. The compensator utilizes a PI controller that controls the error signal to zero. The proposed technique further contains a residual error compensator to completely eliminate miscellaneous disturbances in the estimated flux. The developed algorithm has been implemented on a 1.1-kW permanent magnet synchronous motor (PMSM) drive to confirm the effectiveness of the proposed scheme.