• Smart Structures and Systems
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• 제16권2호
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• pp.329-345
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• 2015

As commonly known, sensor errors and faulty signals may potentially lead structures in vibration to catastrophic failures. This paper presents a new approach to deal with sensor errors/faults in vibration control of structures by using the Fault detection and isolation (FDI) technique. To demonstrate the effectiveness of the approach, a space truss structure with semi-active devices such as Magneto-Rheological (MR) damper is used as an example. To address the problem, a Linear Matrix Inequality (LMI) based fixed-order $H_{\infty}$ FDI filter is introduced and designed. Modeling errors are treated as uncertainties in the FDI filter design to verify the robustness of the proposed FDI filter. Furthermore, an innovative Fuzzy Fault Tolerant Controller (FFTC) has been developed for this space truss structure model to preserve the pre-specified performance in the presence of sensor errors or faults. Simulation results have demonstrated that the proposed FDI filter is capable of detecting and isolating sensor errors/faults and actuator faults e.g., accelerometers and MR dampers, and the proposed FFTC can maintain the structural vibration suppression in faulty conditions.

• 한국정보처리학회논문지
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• 제7권12호
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• pp.3848-3854
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• 2000

제어 시스템에서 요구되는 특성과 제공되는 하드웨어들의 기능을 유지하는 것은 만족할만한 제어기를 설계하는데 있어서 중요하다. 제어시스템의 하드웨어들 중에서 센서는 내·외부 외란에 가장 취약하지만, 정확하고 신뢰성있는 센서값을 유지하는 것은 좋은 제어기 성능을 위해 꼭 필요하다. 센서에 오류가 발생했을 경우, 센서 출려과 제어기 출력 같은 값을 사용하여 이를 검출하고, 오류 증상을 분석하여 오류 요인을 판단한다. 오류 요인에 따라 원래 센서값 대신 Self-Validating 센서값을 사용한다. 본 논문에서는 유연 링크 시스템에서 광센서 모듈의 오류 문제들에 Self-Validating 센서를 응용하여 이의 유효성을 보이고, 센서 오류가 발생하였을 때 만족할만한 성능을 제공할 수 있는 디지털 제어기를 제안한다.

• Journal of Power Electronics
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• 제14권5호
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• pp.967-979
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• 2014

This paper focuses on speed and current sensor fault detection and isolation (FDI) for induction motor (IM) drives. A new, accurate and high-efficiency FDI approach is proposed so that a system can continue operating with good performance even in the presence of speed sensor faults, current sensor faults or both. The proposed three paralleled adaptive observers are capable of current sensor fault detection and localization. By using observers, the rotor flux and rotor speed can be estimated which allows the system to run under the speed sensorless vector control mode when a speed sensor fault occurs. In order to detect speed sensor faults, a threshold-based scheme is proposed. To verify the feasibility and effectiveness of the proposed FDI strategy, experiments are carried out under different conditions based on a dSPACE DS1104 induction motor drive platform.

• Smart Structures and Systems
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• 제20권1호
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• pp.43-52
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• 2017

Structural health monitoring has drawn great attention in the field of civil engineering in past two decades. These structural health monitoring methods evaluate structural integrity through high-quality sensor measurements of structures. Due to electronic deterioration or aging problems, sensors may yield biased signals. Therefore, the objective of this study is to develop a fault detection method that identifies malfunctioning sensors in a sensor network. This method exploits the autoregressive modeling technique to generate a bank of Kalman estimators, and the faulty sensors are then recognized by comparing the measurements with these estimated signals. Three types of faults are considered in this study including the additive, multiplicative, and slowly drifting faults. To assess the effectiveness of detecting faulty sensors, a numerical example is provided, while an experimental investigation with faults added artificially is studied. As a result, the proposed method is capable of determining the faulty occurrences and types.

• Journal of information and communication convergence engineering
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• 제18권3호
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• pp.201-206
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• 2020

This paper presents a new method for controlling the current of lighting LEDs without current sensors. This method can be used as backup against LED current sensor faults. LED lighting requires a circuit with a constant current in order to maintain the same brightness when the ambient temperature changes. Therefore, we propose a new current estimation method to provide backup in case of current sensor faults based on the calculation of the inductor current. In the fabricated circuit, the average current changes from 144.03 mA to 155.97 mA when the ambient temperature changes from 0℃ to 60℃. The application of this study can enable the fabrication of a driving IC for LEDs in the form of a single chip without sensing resistors. This is expected to reduce the complexity of the peripheral circuit and enable precise feedback control.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.760-765
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• 2004

One of the obstacles for a magnetic bearing to be used in the wide range of industrial applications is the failure modes associated with magnetic bearings, which we don't expect for conventional passive bearings. These failure modes include electric power outage, power amplifier faults, position sensor faults, and the malfunction of controllers. Fault-tolerant magnetic bearing systems have been proposed so that the system can operate in spite of some faults in the system. In this paper, we designed and implemented a fault-tolerant magnetic bearing system for a turbo-molecular vacuum pump. The system can cope with the actuator/amplifier faults as well as the faults in position sensors, which are the two major fault modes in a magnetic bearing system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2357-2360
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• 2002

For the satisfying performance of a oil lubricator, design of a oil controller for the system which meets the required specifications and its supporting hardware that keep their functioning is important. Among the hardware of a control system, oil system are most vulnerable to malfunction. Thus it is necessary to keep track of accurate and reliable oil readings for good fusion oil lubricator performance. In case of oil lubricator, data loss, ssr trigger error faults, they are detected by examining the data system output values and the major values of the system, and then the faults are recognized by the analysis of symptoms of faults. If necessary electronic-sensor values are synthesized according to the types of faults, and then they are used for the controller instead of the raw data. In this paper, a fast-32bit cpu microprocessor applied to the control of flexible link system with the sensor fault problems in the error modulo for exact positioning to show the applicability. It is shown that the fusion oil lubricator can provide a satisfactory loop performance even when the sensor faults occure.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계합동학술대회 논문집
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• pp.137-140
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• 2002

For the satisfying performance of a oil lubricator, design of a oil controller for the system which meets the required specifications and its supporting hardware that keep their functioning is important. Among the hardware of a control system, oil system are most vulnerable to malfunction. Thus it is necessary to keep track of accurate and reliable oil readings for good fusion oil lubricator performance. In case of oil lubricator, data loss, ssr trigger error faults, they are detected by examining the data system output values and the major values of the system, and then the faults are recognized by the analysis of symptoms of faults. If necessary electronic-sensor values are synthesized according to the types of faults, and then they are used for the controller instead of the raw data. In this paper, a fast-32bit cpu micorprocessor applied to the control of flexible link system with the sensor fault problems in the error module for exact positioning to show the applicability. It is shown that the fusion oil lubricator can provide a satisfactory loop performance even when the sensor faults occure

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.97-104
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• 2008

Most of engine control systems for helicopter turboshaft engines are equipped with dual sensors. For the system with dual redundancy, analytic methods are used to detect faults based on the system dynamical model. Helicopter engine dynamics are affected by aerodynamic torque induced from the dynamics of the main rotor. In this paper an engine model including the rotor dynamics is constructed for the T700-GE-700 turboshaft engine powering UH-60 helicopter. The singular value decomposition(SVD) method is applied to the developed model in order to detect sensor faults. The SVD method which do not need an additional computation to generate residual uses the characteristics that the system outputs in direction of the left singular vector if an input is applied in direction of the right singular vector. Simulations show that the SVD method works well in detecting and isolating the sensor faults.

• 전기학회논문지
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• 제58권8호
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• pp.1532-1537
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• 2009

Nowadays the diversity and large-capacity of electric appliances are strong effect on electrical fires augment in an alarming way. But, as the inactive response characteristics of the existing RCD (Residual Current protective Device) used on low voltage power distribution lines, so control of overload and electric short circuit faults, major causes of electrical fires, are not enough. Therefore this paper is confirmed the unreliability of the existing RCD by electrical faults simulation and is proposed a auxiliary trip device of RCD by using a high precision current sensor (namely, reed switch) for the prevention of electrical disasters in low voltage power distribution lines caused by overload or electric short circuit faults. The sensitive reed switch in the proposed ATD (auxiliary trip device) exactly detects the increased magnetic flux with the overload or the short current caused by a number of electrical faults, and then rapidly cuts off the existing RCD. The proposed auxiliary trip device of RCD is confirmed the excellent characteristics in response velocity and accuracy in comparison with the conventional circuit breaker through various operation performance analysis. The proposed ATD can also prevent electrical disaster, like as electrical fires, which resulted from the malfunction and inactive response characteristics of the existing RCD.