• Journal of Electrical Engineering and Technology
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• 제8권4호
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• pp.752-759
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• 2013

This paper proposes a method for fault diagnosis and fault-tolerant control of DC-link voltage sensor for two-stage three-phase grid-connected PV inverters. Generally, the front-end DC-DC boost converter tracks the maximum power point (MPP) of PV array and the rear-end DC-AC inverter is used to generate a sinusoidal output current and keep the DC-link voltage constant. In this system, a sensor is essential for power conversion. A sensor fault is detected when there is an error between the sensed and estimated values, which are obtained from a DC-link voltage sensorless algorithm. Fault-tolerant control is achieved by using the estimated values. A deadbeat current controller is used to meet the dynamic characteristic of the proposed algorithm. The proposed algorithm is validated by simulation and experiment results.

• 자동차안전학회지
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• 제14권2호
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• pp.26-38
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• 2022

This paper proposes multiple RLS and actuator performance index-based adaptive actuator fault-tolerant control and detection algorithms for longitudinal autonomous driving. The proposed algorithm computes the desired acceleration using feedback law for longitudinal autonomous driving. When actuator fault or performance degradation exists, it is designed that the desired acceleration is adjusted with the calculated feedback gains based on multiple RLS and gradient descent method for fault-tolerant control. In order to define the performance index, the error between the desired and actual accelerations is used. The window-based weighted error standard deviation is computed with the design parameters. Fault level decision algorithm that can represent three fault levels such as normal, warning, emergency levels is proposed in this study. Performance evaluation under various driving scenarios with actuator fault was conducted based on co-simulation of Matlab/Simulink and commercial software (CarMaker).

• 한국산업정보학회:학술대회논문집
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• 한국산업정보학회 1997년도 추계학술대회 발표논문집:21세기를 향한 정보통신 기술의 전망
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• pp.417-433
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• 1997

A real-time operating system has focused primary on techniques to minimize processing time, with a secondary emphasis on system reliability issues. Conversely, fault-tolerant system has concentrated on using recourse and information redundancy to maximize the availability and reliability of the system, with a lesser emphasis on performance. We have developed a fault-tolerant and real-time operations system which support a powerful concurrent runtime environment under the above requirements. In this paper, we present an overview of real-time systems, design and implementation of a duplex architecture using advanced concepts and technologies such as fast " fault detection", "fault isolation" and "fault recovery" Because the duplex architecture has two dentical hardware elements and has several recovery steps and hierarchy to facilitate a fast recovery which must be proceeded by a prompt fault detection and isolation. Thus it makes possible to minimize the overhead of the systems including hardware and software and guarantee the service continuity of he systems.

• Journal of Power Electronics
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• 제14권4호
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• pp.695-703
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• 2014

In this paper, a fault detection scheme for DC-link voltage sensor and its fault tolerant control strategy for three-phase AC/DC/AC PWM converters are proposed, where the Luenberger observer is applied to estimate the DC-link voltage. The Luenberger observer is based on a converter model, which is derived from the voltage equations of a grid-side converter and the power balance on a DC link. A fault of the voltage sensor is detected by comparing the measured value of the DC-link voltage with the estimated one. When a sensor fault is detected, a fault tolerant control strategy is performed, where the estimated DC-link voltage is used for the feedback control. The estimation error from the observer is about 1.5 V, which is sufficiently accurate for feedback control. In addition, it is shown that the observer performance is robust to parameter variations of the converter. The validity of the proposed method has been verified by simulation and experimental results.

• 전기학회논문지
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• 제64권5호
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• pp.718-725
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• 2015

This paper proposes a novel level-shifted PWM (LS-PWM) strategy for fault tolerant cascaded multilevel inverter. Most proposed fault-tolerant operation methods in many of studies are based on a phase-shifted PWM (PS-PWM) method. To apply these methods to multilevel inverter systems using LS-PWM, two additional steps will be implemented. During the occurrence of a single-inverter-cell fault, the carrier bands scheme is reconfigured and modulation levels of inverter cells are reassigned in this proposed fault-tolerant operation. The proposed strategy performs balanced three-phase line-to-line voltages and line currents when a switching device fault occurs in a cascaded multilevel inverter using LS-PWM. Simulation and experimental results are included in the paper to verify the proposed method.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제21권1호
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• pp.29-39
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• 2015

무인기 항법 시스템의 개발 및 실험에는 위험 요소가 많아 가벼운 하중을 유지하면서도 고장 감내를 지원하는 시스템이 요구된다. 본 논문에서는 CPU 시간과 메모리를 독립적으로 사용하는 파티션을 기반으로, 단일 및 복수 개의 FCC(Flight Control Computer)에서 항법용 주 및 보조 OFP(Operational Flight Program) 파티션들을 독립적으로 수행하는 고장 감내 무인기 항법 시스템에 대해 기술한다. 개발된 시스템은 이중화된 두 개의 FCC를 사용하고, 각 보드에서는 OFP 파티션을 이중화하여 개발 중인 OFP 및 검증된 OFP 시스템을 독립적으로 수행한다. 이러한 고장 감내 시스템은 감내 하중이 작은 무인기의 경우에 하나의 FCC만 사용하여도 S/W 이중화에 따른 고장 감내가 가능하며, H/W 고장 감내도 필요한 중대형 무인기의 경우, 이중화 파티션을 수행하는 보조 FCC까지 사용한다. 이와 같은 파티션 기반 고장 감내 항법 시스템은 그 개발 단계에서 실험의 많은 위험 요소를 제거할 것이다.

• 전자공학회논문지SC
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• 제42권3호
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• pp.1-10
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• 2005

본 논문에서는 기구학적 구속조건을 고려한 육각 보행 로봇의 새로운 내고장성 걸음새를 제안한다. 본 논문에서 고려하고 있는 고장은 관절고착고장으로 로봇 다리의 관절 하나가 어떤 위치에 고착되어서 보행이 끝날 때까지 움직일 수 없는 상태를 말한다. 본 논문에서는 먼저 육각 보행 로봇의 직선 보행을 위한 기존의 내고장성 걸음새가 고장 난 다리의 기구학적 구속조건에 따라서 교착 상태에 빠질 수도 있음을 해석적으로 증명한다. 그런 다음 이러한 교착 상태를 회피하기 위해서 새로운 내고장성 걸음새 계획을 제안한다. 제안하는 내고장성 걸음새는 다리의 궤적을 변경함으로써 고장 난 다리가 야기하는 교착 상태에서 벗어날 수 있으며, 기존 내고장성 걸음새의 다리 움직임 순서와 보폭을 그대로 유지한다. 제안한 걸음새 계획의 우수성을 입증하기 위해서 평탄 지형에서 정상적인 걸음새로 걷고 있는 육각 보행 로봇이 고장이 일어난 후 제안한 걸음새 계획을 이용하여 교착 상태에서 벗어나 내고장성 걸음새로 전이하는 사례 연구도 기술한다.

• 한국정보과학회논문지:시스템및이론
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• 제30권3_4호
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• pp.160-167
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• 2003

정적 shuffle-exchange 네트워크는 여러 응용 알고리듬에 적용되고 현재 많이 사용되는 다중 단계 네트워크에 비해 적은 하드웨어를 사용하는 등 많은 장점이 있으나 아직까지 어떤 병렬처리 컴퓨터에도 채택된 없었다. 그 이유 중에 하나는 결함 내성 기능이 없었기 때문이다. 본 논문에서는 다중 결함 포용 정적 shuffle-exchange network를 소개한다. 본 논문에서 제시되는 결함 포용 정적shuffle-exchange 네트워크는 k 결함을 제어하기 위해서 최소 2k의 추가 처리 요소들과 각 처리 요소들은 최대 4k의 추가 shuffle 링크를 필요로 한다. k 결함 내성을 가진 정적 shuffle-exchange 네트워크를 m개의 동일한 모듈로 분리하여 네트워크의 신뢰성을 증가시키는 것을 보였다.

• International Journal of Automotive Technology
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• 제7권6호
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• pp.729-739
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• 2006

This paper describes an active fault-tolerant control system for an induction motor drive that propels an Electrical Vehicle(EV) or a Hybrid one(HEV). The proposed system adaptively reorganizes itself in the event of sensor loss or sensor recovery to sustain the best control performance given the complement of remaining sensors. Moreover, the developed system takes into account the controller transition smoothness in terms of speed and torque transients. In this paper which is the sequel of (Diallo et al., 2004), we propose to introduce more advanced and intelligent control techniques to improve the global performance of the fault-tolerant drive for automotive applications(e.g. EVs or HEVs). In fact, two control techniques are chosen to illustrate the consistency of the proposed approach: sliding mode for encoder-based control; and fuzzy logics for sensorless control. Moreover, the system control reorganization is now managed by a fuzzy decision system to improve the transitions smoothness. Simulations tests, in terms of speed and torque responses, have been carried out on a 4-kW induction motor drive to evaluate the consistency and the performance of the proposed fault-tolerant control approach.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.239-243
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• 1993

In this paper, a fault-tolerant controller using duplex processors has been designed and implemented. The PI controller is adopted as the control algorithm and the fault-tolerant control system is implemented by two single chip processors(MCS-96). Performances of the control system designed here have been shown via a simulation with application to a pitch channel autopilot.