• Title/Summary/Keyword: Variable Parameter

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Velocity Control of an Electro-hydraulic Servo System with Integral Variable Structure Controller (적분 가변구조제어기를 갖는 전기유압 서보시스템의 속도제어)

  • Huh, J.Y.
    • Journal of Drive and Control
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    • v.18 no.4
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    • pp.52-58
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    • 2021
  • The variable structure controller is designed such that in sliding mode, the system moves along the switching plane in the vicinity of the switching plane, thus it is robust because it is not affected by the parameter fluctuations of the plant. However, a controller based on a variable structure may not meet the desired performance when it is commanded to track any input or is exposed to disturbances. This study proposes a sliding mode controller that follows the IVSC (Integral Variable Structure Control) approach with ELO (Extended Luenberger observer) to solve this problem. The proposed sliding mode control is applied to the velocity control of the hydraulic motor. The sliding plane was determined by the pole placement, and the control input was designed to ensure the existence of the sliding mode. The feasibility of modeling and controller are reviewed by comparing with conventional proportional-integral control through computer simulation using MATLAB software and experimenting on the cases of significant plant parameter fluctuations and disturbances.

Analysis of a Modified Stochastic Gradient-Based Filter with Variable Scaling Parameter (가변 축척 매개변수를 가진 변형 확률적 경사도 기반 필터의 해석)

  • Kim, Hae-Jung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.12C
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    • pp.1280-1287
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    • 2006
  • We propose a modified stochastic gradient-based (MSGB) filter showing that the filter is the solution to an optimization problem. This paper analyzes the properties of the MSGB filter that corresponds to the nonlinear adaptive filter with additional update terms, parameterized by the variable scaling factor. The variably parameterized MSGB filter plays a role iii connecting the fixed parameterized MSGB filter and the null parameterized MSGB filter through variably scaling parameter. The stability regions and misadjustments are shown. A system identification is utilized to perform the computer simulation and demonstrate the improved performance feature of the MSGB filter.

Position error compensation of the multi-purpose overload robot in nuclear power plants

  • Qin, Guodong;Ji, Aihong;Cheng, Yong;Zhao, Wenlong;Pan, Hongtao;Shi, Shanshuang;Song, Yuntao
    • Nuclear Engineering and Technology
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    • v.53 no.8
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    • pp.2708-2715
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    • 2021
  • The Multi-Purpose Overload Robot (CMOR) is a key subsystem of China Fusion Engineering Test Reactor (CFETR) remote handling system. Due to the long cantilever and large loads of the CMOR, it has a large rigid-flexible coupling deformation that results in a poor position accuracy of the end-effector. In this study, based on the Levenberg-Marquardt algorithm, the spatial grid, and the linearized variable load principle, a variable parameter compensation model was designed to identify the parameters of the CMOR's kinematics models under different loads and at different poses so as to improve the trajectory tracking accuracy. Finally, through Adams-MATLAB/Simulink, the trajectory tracking accuracy of the CMOR's rigid-flexible coupling model was analyzed, and the end position error exceeded 0.1 m. After the variable parameter compensation model, the average position error of the end-effector became less than 0.02 m, which provides a reference for CMOR error compensation.

Structural Change and Stability in a Long-Run Parameter (장기모수의 구조변화와 안정성)

  • Kim, Tae-Ho
    • Communications for Statistical Applications and Methods
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    • v.18 no.4
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    • pp.495-505
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    • 2011
  • This study performs statistical tests for stability of a long-run relationship in the telecommunication market system by identifying the time path of a recursively estimated cointegration parameter. A dummy variable is used to recover stability for the period that the hypothesis of stable cointegration is rejected, and then a proper cointegrating relation is derived. A dummy variable appears to reflect the structural change in the cointegrating relation according to the analytical results for the error correction term.

A Study on Time-Varying Sliding Regime of VSC System (가변구조제어계의 시변 슬라이딩 레짐에 관한 연구)

  • Kim, Joong-Wan;Lee, Man-Hyung
    • Journal of the Korean Society for Precision Engineering
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    • v.6 no.2
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    • pp.30-39
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    • 1989
  • Variable structure control (VSC) systems control the state vectors using sliding regime (SR) constructed switching logic, switching plane and control law. Saturation function switching logic is used to improve the drawback which occurs in traditional sign function switching logic. Switching plane with time-varying parameter is proposed to improve the drawback which occurs in switching plane with constant parameter and it is suggested the control law which has time-varying parameter. The stability of VSC system controlled by proposed time-varying SR is discussed, and the good control behavior was shown through computer simulation using proposed SR.

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A Study on the Performance Improvement of a Nonlinear Fuzzy PID Controller (비선형 퍼지 PID 제어기의 성능 개선에 관한 연구)

  • 김인환;이병결;김종화
    • Journal of Advanced Marine Engineering and Technology
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    • v.27 no.7
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    • pp.852-861
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    • 2003
  • In this paper, in order to improve the disadvantages of the fixed design-parameter fuzzy PID controller. a new fuzzy PID controller named a variable design-parameter fuzzy PID controller is suggested. The main characteristic of the suggested controller is to adjust design-parameters of the controller by comparing magnitudes between fuzzy controller inputs at each sampling time when controller inputs are measured. As a result. all fuzzy input partitioned spaces converge within a time-varying normalization scale. and the resultant PID control action can always be applied precisely regardless of operating input magnitudes. In order to verify the effectiveness of the suggested controller. several a computer simulations for a nonlinear system are executed and the control parameters of the variable design-parameter fuzzy PID controller are throughly analyzed.

Optimal Design of c Control Chart using Variable Sampling Interval (가변추출간격을 이용한 c 관리도의 최적설계)

  • Park, Joo-Young
    • Journal of the Korea Safety Management & Science
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    • v.9 no.2
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    • pp.215-233
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    • 2007
  • Even though the ad hoc Shewhart methods remain controversial due to various mathematical flaws, there is little disagreement among researchers and practitioners when a set of process data has a skewness distribution. In the context and language of process control, the error related to the process data shows that time to signal increases when a control parameter shifts to a skewness direction. In real-world industrial settings, however, quality practitioners often need to consider a skewness distribution. To address this situation, we developed an enhanced design method to utilize advantages of the traditional attribute control chart and to overcome its associated shortcomings. The proposed design method minimizes bias, i.e., an average time to signal for the shift of process from the target value (ATS) curve, as well as it applies a variable sampling interval (VSI) method to an attribute control chart for detecting a process shift efficiently. The results of the factorial experiment obtained by various parameter circumstances show that the VSI c control chart using nearly unbiased ATS design provides the smallest decreasing rate in ATS among other charts for all experimental cases.

Multiparameter CUSUM charts with variable sampling intervals

  • Im, Chang-Do;Cho, Gyo-Young
    • Journal of the Korean Data and Information Science Society
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    • v.20 no.3
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    • pp.593-599
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    • 2009
  • We consider the problem of using control charts to monitor more than one parameter with emphasis on simultaneously monitoring the mean and variance. The fixed sampling interval (FSI) control charts are modified to use variable sampling interval (VSI) control charts depending on what is being observed from the data. In general, approaches of monitoring the mean and variance simultaneously is to use separate charts for each parameter and a combined chart. In this paper, we use three basic strategies which are separate Shewhart charts for each parameter, a combined Shewhart chart and a combined CUSUM chart. We showed that a combined VSI CUSUM chart is comparatively more efficient than any other chart if the shifts in both mean and variance are small.

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A Study on Dynamic Parameter Design Procedure Considering the Signal Factor and the Quality Characteristics with Continuous Variable (신호인자와 특성치가 연속형 변수인 경우를 고려한 동적파라미터 설계 절차에 관한 연구)

  • 배홍석;이만웅;송서일
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.19 no.39
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    • pp.243-254
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    • 1996
  • In this study, a model and an analysis method for parameter design is presented a linear relation between the input signal and the ideal value of a performance characteristic. Furthermore, There presented a new performance measure, expected quality loss after adjustment, which is proved to be equivalent to Taguchi's SN ratio approximately. On the basis of this, a two-step optimization procedure is proposed for parameter design considering the signal factor and the quality characteristics with continuous variable. Proposed procedure and Taguchi two-stage procedure are compared.

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Digital current control for BLDC motor using variable structure controller and artificial neural network (가변구조제어기와 인공 신경회로망에 의한 BLDC모터의 디지털 전류제어)

  • 박영배;김대준;최영규
    • 제어로봇시스템학회:학술대회논문집
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    • 1997.10a
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    • pp.504-507
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    • 1997
  • It is well known that Variable Structure Controller(VSC) is robust to parameters variation and disturbance but its performance depends on the design parameters such as switching gain and slope of sliding surface. This paper proposes a more robust VSC that is composed of local VSC's. Each local VSC considers the local system dynamics with narrow parameter variation and disturbance. First we optimize the local VSC's by use of Evolution Strategy, and next we use Artificial Neural Network to generalize the local VSC's and construct the overall VSC in order to cover the whole range of parameter variation and disturbance. Simulation on BLDC motor current control shows that the proposed VSC is superior to the conventional VSC.

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