• Title/Summary/Keyword: Multiple observer

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Improved Estimation Method for the Capacitor Voltage in Modular Multilevel Converters Using Distributed Neural Network Observer

  • Mehdi Syed Musadiq;Dong-Myung Lee
    • Journal of IKEEE
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    • v.27 no.4
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    • pp.430-438
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    • 2023
  • The Modular Multilevel Converter (MMC) has emerged as a key component in HVDC systems due to its ability to efficiently transmit large amounts of power over long distances. In such systems, accurate estimation of the MMC capacitor voltage is of utmost importance for ensuring optimal system performance, stability, and reliability. Traditional methods for voltage estimation may face limitations in accuracy and robustness, prompting the need for innovative approaches. In this paper, we propose a novel distributed neural network observer specifically designed for MMC capacitor voltage estimation. Our observer harnesses the power of a multi-layer neural network architecture, which enables the observer to learn and adapt to the complex dynamics of the MMC system. By utilizing a distributed approach, we deploy multiple observers, each with its own set of neural network layers, to collectively estimate the capacitor voltage. This distributed configuration enhances the accuracy and robustness of the voltage estimation process. A crucial aspect of our observer's performance lies in the meticulous initialization of random weights within the neural network. This initialization process ensures that the observer starts with a solid foundation for efficient learning and accurate voltage estimation. The observer iteratively updates its weights based on the observed voltage and current values, continuously improving its estimation accuracy over time. The validity of proposed algorithm is verified by the result of estimated voltage at each observer in capacitor of MMC.

Optimal Control for Multiple Serial Sampling Systems (다중시리얼 샘플링 시스템의 최적제어)

  • Yeon Wook Choe
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.28B no.10
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    • pp.771-782
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    • 1991
  • In industrial multivariable plants, it is ofte the case that the plant outputs are measured in similar components not simultaneously but serially. In this paper, the problem of estimating the state vector of the plant based on the data obtained from such a measuring scheme is considered, and a special type of observer(referred to as a $'$multiple serial-sampling$'$ type observer) which renews its internal states whenever a new group of data is obtained is proposed. It is proved that such an observer can be constructed for almost every sampling period if the palnt is observable as a continuous-time multivariable system, and that the poles of the closed-loop system using the multiple serial-sampling type observer consist of the poles of the observer and those of the state feedback system. The behaviors of the observer and the closed-loop system are studied by simulation. The results of simulation indicate that a multiple serial-ampling type observer can estimate the state of the plant more accurately than the ordinary type observers and improve the closed-loop performance, especially, in the existence of measuring noise.ng noise.

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A Study for the Design of Multiple Serial-Sampling Type Observer (다중시리얼샘플링형 관측기의 설계를 위한 연구)

  • Yeon Wook Choe
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.31B no.3
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    • pp.47-52
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    • 1994
  • In industrial multivariable plants, it is often the case that all of plant outputs are measured not simultaneously, but seriallu. While Reference 1 proposed a special type of observer (referred to as "serial-sampling" type obserrversL. which was provento be very effective in this situation, it alsopointed out that the observer may have some minor problems in case of practical applications. In this paper, it isshown that these kind of problems can be resolved by proving the existence of the solution of the simultaneous equations (35) of Reference 1.

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Fault Detection of Gantry Crane System By using Observation Technique (관측기법을 이용한 갠트리 크레인의 고장 진단)

  • 김환성;김명규;유삼상
    • Journal of Advanced Marine Engineering and Technology
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    • v.25 no.4
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    • pp.880-888
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    • 2001
  • This paper presents a fault detection asnd isolation algorithm for highly reliable gantry crane system. The algorithm is constructed by multiple PI observer technique, and the magnitude of actuator fault can be estimated by using integrated estimated output error. Also, the complex actuator and /or sensor fault can be detected and isolated by monitoring the integrated error and the estimated state error. Considering the actuator and/or the sensor fault, we verify that these fault can be detected and isolated through simulation. Lastly, we show a simple reliable control method by using the detected fault signal and an added observer.

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A New Dynamic Residual Generator for Process Fault Detection (프로세스고장검출을 위한 새로운 잔차발생기구)

  • 이기상;이상문
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.52 no.10
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    • pp.575-582
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    • 2003
  • A new FDOs (fault diagnostic observers) and the residual generation schemes using the FDOs are suggested for the process fault detection and isolation of linear (control) systems. The design method of the FDO is described, first, for the full measurement systems. Then it is extended for the systems with unmeasurable state variables. An unknown input observer is proposed and applied for the extension. The size of the observer bank may be the smallest, specially in full measurement systems, because the order of the proposed FDO is very low. In spite of the simplicity, the scheme provides the same information for the detection and isolation of the anticipated faults as the conventional multiple observer based schemes. The residuals may be structured so that fault isolation can be performed by pre-selected logic. An FDIS using the proposed scheme is constructed for the model of the four-tank system. Simulation results show the practical feasibility of the proposed scheme.

An Instrument Fault Detection Scheme using Function Observers (함수관측자를 이용한 장치고장검출 기법)

  • Lee, Sang-Moon;Lee, Kee-Sang
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.55 no.3
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    • pp.91-97
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    • 2006
  • A major difficulty with the practical application of the multiple observer based IFDI schemes is the computational burden of the residual generation. In this paper, a new residual generator that employs function observers is proposed to reduce the computational burden, and the design methods of the IFDIS, equipped with the residual generator, are presented. The function observers employed in the residual generator can be considered as a dual of the unknown input (function) observer And it can be designed to estimate the measurement errors that are due to sensor faults. The error estimates are further processed to generate the residuals by which reliable fault detection/isolation result car be obtained. The proposed scheme is more useful, in real-time application, than any other multiple state observer based IFDISs. It can be effectively applied to fault tolerant control because the failure effects can be compensated by the use of the estimates of measurement errors. The proposed IFDI scheme is applied to an inverted pendulum control system for the IFDI of failed sensor and fault compensation.

Motion Control of an Uncertain robotic Manipulator System via Neural Network Disturbance Observer (신경회로망 외란 관측기를 이용한 불확실한 로봇 시스템의 운동 제어)

  • Kim, Eun-Tai;Kim, Han-Jung
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.39 no.4
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    • pp.6-15
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    • 2002
  • A neural network disturbance observer for a robotic manipulator is derived in this paper. The neural network used as the disturbance observer is a feedforward MLP(multiple-layered perceptron) network. The uniform ultimate boundness(UUB) of the proposed neural disturbance observer and the control error within a sufficiently small compact set is guaranteed. This neural disturbance observer method overcomes the disadvantages of the existing adaptive control methods which require the tedious analysis of the regressor matrix of the given manipulator. The effectiveness of the proposed neural disturbance observer is demonstrated by the application to the three-link robotic manipulator.

A Fuzzy Model Based Sensor Fault Detection Scheme for Nonlinear Dynamic Systems (퍼지모델을 이용한 비선형시스템의 센서고장 검출식별)

  • Lee, Kee-Sang
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.2
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    • pp.407-414
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    • 2007
  • A sensor fault detection scheme(SFDS) for a class of nonlinear systems that can be represented by Takagi-Sugeno fuzzy model is proposed. Basically, the SFDS may be considered as a multiple observer scheme(MOS) in which the bank of state observers and the detection & isolation logic are included. However, the proposed scheme has two great differences from the conventional MOSs. First, the proposed scheme includes fuzzy fault detection observers(FFDO) that are constructed based on the T-S fuzzy model that provides very good approximation to nonlinear dynamic systems. Secondly, unlike the conventional MOS, the FFDOS are driven not parallelly but sequentially according to the predetermined sequence to avoid the massive computational burden, which is known to be the biggest obstacle to the practical application of the multiple observer based FDI schemes. During the operating time, each FFDO generates the residuals carrying the information of a specified fault, and the corresponding fault detection logic unit performs the logical operations to detect and isolate the fault of interest. The proposed scheme is applied to an inverted pendulum control system for sensor fault detection/isolation. Simulation study shows the practical feasibility of the proposed scheme.

A GPU based Rendering Method for Multiple-view Autostereoscopic Display (무안경식 다시점 입체 디스플레이를 위한 GPU기반 렌더링 기법)

  • Ahn, Jong-Gil;Kim, Jin-Wook
    • Journal of the HCI Society of Korea
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    • v.4 no.2
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    • pp.9-16
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    • 2009
  • 3D stereo display systems gain more interests recently. Multiple-view autostereoscopic display system enables observers to watch stereo image from multiple viewpoints not wearing specific devices such as shutter glasses or HMD. Therefore, the Multiple-view autostereoscopic display is being spotlighted in the field of virtual reality, mobile, 3D TV and so on. However, one of the critical disadvantages of the system is that observer can enjoy the system only in a small designated area where the system is designed to work properly. This research provides an effective way of GPU based rendering technique to present seamless 3D stereo experiences from an arbitrary observer's view position.

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On the Fault Detection and Isolation Systems using Functional Observers (함수 관측자를 이용한 고장검출식별기법에 관한 연구)

  • Lee, Kee-Sang;Ryu, Ji-Su
    • Journal of Institute of Control, Robotics and Systems
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    • v.9 no.11
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    • pp.883-890
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    • 2003
  • Two GOS (Generalized Observer Scheme) type Fault Detection Isolation Schemes (FDIS), employing the bank of unknown input functional observers (UIFO) as a residual generator, are proposed to make the practical use of the multiple observer based FDIS. The one is IFD (Instrument Fault Detection) scheme and the other is PFD (Process Fault Detection) scheme. A design method of UIFO is suggested for robust residual generation and reducing the size of the observer bank. Several design objectives that can be achieved by the FDI schemes and the design methods to meet the objectives are described. An IFD system is constructed for the Boeing 929 Jetfoil boat system to show the effectiveness of the propositions. Major contributions of this paper are two folds. Firstly, the proposed UIFO approaches considerably reduce the size of residual generator in the GOS type FDI systems. Secondly, the FDI schemes, in addition to the basic functions of the conventional observer-based FDI schemes, can reconstruct the failed signal or give the estimates of fault magnitude that can be used for compensating fault effects. The schemes are directly applicable to the design of a fault tolerant control systems.