• Journal of the Korean Society for Precision Engineering
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• v.14 no.2
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• pp.41-47
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• 1997

Fault diagnosis problem is currently a subject of extensive research in the control field. Although there are several works on the fault detection and isolation observers and the residual generators, those are con- cerned with only the detection of actuator failures or sensor failures. So, the perfect detection and isolation for the actuator and sensor failures is strongly required in the field of the practical applications. In this paper, a strategy of fault diagnosis using multiple proportional integral (PI) observers including the magnitude of actuator failures is provided. It is shown that actuator failures are detected and isolated perfectly by monitoring the integrated error between actual output and estimated output by a PI observer. Also in presence of complex actuator and sensor failures, these failures are detected and isolated by multiple PI observers.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1440-1443
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• 1997

The optimal residual generator based on parity relation approach for the fault detection and isolation of a arge diesel engine actuator position servo system is presented. The closed-loop residual generator is designed to have robustness against modeling errors and noise. Main purpose of the fault detection and isolation system in the process is to detect and isolate two important faults, i.e., actuatro fault and fault of speed sensor, that, if not detected and compensated, degrade the overall control system performance. Simulation results are give to show the practical applicability of the fault detecrtion and isloation scherme.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.174-176
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• 2007

Because of accident or leak of electricity, high voltage electricity can be conducted to vehicle chassis and damage human. Therefore the unit for detecting ground fault is necessary to minimize loss of life or equipment damage. Isolation resistance must be monitored for detecting ground fault. GFD(Ground Fault Detection) unit continually generate the pulse voltage between high voltage network and chassis. This will be sensing the returned current, calculate the isolation resistance and make decision the ground fault. This paper describes the method detecting ground fault.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.3
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• pp.244-251
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• 1997

In this paper, we propose a fault diagnosis algorithm to detect and isolate multiple faults in a system. The proposed fault diagnosis algorithm is based on a multiple fault classifier which consists of two ART2 NN(adaptive resonance theory2 neural network) modules and the algorithm is composed of three main parts - parameter estimation, fault detection and isolation. When a change in the system occurs, estimated parameters go through a transition zone in which residuals between the system output and the estimated output cross the threshold, and in this zone, estimated parameters are transferred to the multiple faults classifier for fault isolation. From the computer simulation results, it is verified that when the proposed diagnosis algorithm is performed successfully, it detects and isolates faults in the position control system of a DC motor.

• International Journal of Control, Automation, and Systems
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• v.5 no.2
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• pp.155-160
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• 2007

A fault detection and isolation (FDI) problem is considered for inertial sensors, such as gyroscopes and accelerometers and a new FDI method for double faults is proposed using reduced-order parity vector. The reduced-order parity vector (RPV) algorithm enables us to isolate double faults with 7 sensors. Averaged parity vector is used to reduce false alarm and wrong isolation, and to improve correct isolation. The RPV algorithm is analyzed by Monte-Carlo simulation and the performance is given through fault detection probability, correct isolation probability, and wrong isolation probability.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2183-2187
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• 2005

In this paper we propose a new fault detection and isolation (FDI) method for those faults of parameter change type. First, we design a residual generator based on the ${\delta}$-operator model of the plant by using the stable pseudo inverse system. Second, the parameter change is estimated by using the property of the block Hankel operator. Third, reliability with respect to stability is quantified. Fourth, the limitations for the meaningful diagnosis in our method are given. The numerical examples demonstrate the effectiveness of the proposed method.

• 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.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.106-107
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• 2019

This paper propose a new 3D SVM method for three-phase four wire inverter for fault isolation at a single line ground fault. The available switching combination for isolation of a single line ground fault was analyzed. Using this method, voltage vector diagrams according to each switching combination were classified according to various ground fault situations, and 3D SVM method was performed by generating command for fault isolation. The proposed methods are mathematically analyzed and verified by PSIM simulation.

• 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.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.32.4-32
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• 2002

We consider inertial navigation system (INS) sensor redundancy and propose a method which uses singular value decomposition to detect and isolate faults when even two sensors have faults simultaneously. When redundant sensor configuration is given, such as symmetric configuration in INS, the range space and null space of configuration matrix are determined. We use null space of configuration matrix and define 21 reference fault vectors which include 6 one-fault vectors and 15 two-fault vectors. Measurements are projected into null space of measurement matrix and compared with 21 normalized reference fault vectors, which determines fault detection and isolation.