• 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.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.411-413
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• 1997

This paper presents the problem of fault-tolerant robust supervisory control of timed discrete event systems (DESs). First the concept of faults is quantitatively defined in timed DESs and fault tolerable event sequences are presented as a desired legal language. Given a timed DES with model uncertainty, the conditions for the existence of a supervisor which always guarantees fault tolerable event sequences embedded in the system are derived.

• Journal of Power Electronics
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• 제15권4호
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• pp.974-986
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• 2015

A novel inverter fault-tolerant control scheme is proposed to drive brushless DC motor. A fault-tolerant inverter and its three fault-tolerant schemes (i.e., phase A fault-tolerant, phase B fault-tolerant, and phase C fault-tolerant) are analyzed. Eight voltage vectors are summarized and a voltage vector selection table is used in the control scheme to improve the midpoint current of the split capacitors. A stator flux observer is proposed. The observer can improve flux estimation, which does not require any speed adaptation mechanism and is immune to speed estimation error. Global stability of the flux observer is guaranteed by the Lyapunov stability analysis. A novel stator resistance estimator is incorporated into the sensorless drive to compensate for the effects of stator resistance variation. DC offset effects are mitigated by introducing an integral component in the observer gains. Finally, a control system based on the control scheme is established. Simulation and experiment results show that the method is correct and feasible.

• 대한기계학회논문집
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• 제18권11호
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• pp.2846-2859
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• 1994

This work deals with kinematic analysis of fault-tolerant 3 degree-of-freedom spherical modules which have force redundancies in its parallel structure. The performance of a redundantly actuated four-legged module with no actuator failure, a single actuator failure, partial and half failure of dual actuator are compared to that of a three-legged module, in terms of maximum force transmission ratio, isotropic characteristics, and fault-tolerant capability. Additionally, a system with an excess number of small floating actuators is considered, and the contribution of these small actuators to the force transmission and fault-tolerant capability is evaluated. This study illustrates that the redundant actuation mode allows significant saving of input actuation effort, and also delivers a fault tolerance.

• 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.

• 대한전자공학회논문지
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• 제24권1호
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• pp.28-34
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• 1987

As a means of improving the reliability of a process control system, a FTCS(Fault Tolerant Control System) is designed and applied to the boiler controller of a thermal power plant. The proposed FTCS has capabilities of fault detection and diagnosis as well as back-up control and bumpless switching. A prototype of FTCS is implemented on an IBM PC as an add-on system and it is experimentally verified by using a boiler process simulator together with simplified analog controllers and a switching unit that an one-fold fault is detected in real time and back-up controller takes over the role of the original controller, controlling the faulty loop.

• 정보처리학회논문지A
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• 제12A권5호
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• pp.421-426
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• 2005

대규모 병렬 연산에 있어서, 계산 노드 혹은 이들을 연결한 통신 네트워크의 장애는 연산 실패로 끝나며, 소중한 계산 시간이 낭비된다. 그러나 현재의 MPI 표준은 이에 대한 대안을 제시하지 않고 있다. 본 논문에서는, 비표준의 무정지형 MPI 라이브러리가 아닌 MPI 표준 함수들만을 사용하여, MPMD 방식의 비동기 연산을 도입한 응용 수준의 무정지형 선형 시스템의 해법을 제안한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 심포지엄 논문집 정보 및 제어부문
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• pp.297-299
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• 2006

Many distributed applications is developed in various environment such as operating system, software platform. So, they exhibit different types of system behavior, status, during the course of their operation. Each such behavior may have different functional and non-functional requirements. Therefore, many distributed application need to fault-tolerance solution. Personal robot provide various service or application. Because personal robot has many application or service, it need to fault-tolerance architecture. A flexible architecture is required to provide dependability. In this paper, it is suggested a fault-tolerant architecture for module-based personal robot with module fault-tolerance, service fault-tolerance.

• Journal of Power Electronics
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• 제16권1호
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• pp.57-65
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• 2016

Reverse matrix converters, which can step up voltages, are suitable for applications with source voltages that are lower than load voltages, such as generator systems. Reverse matrix converter topologies are advantageous because they do not require additional components to conventional matrix converters. In this paper, a detection method and a post-fault modulation strategy to operate a converter as close as possible to its desired normal operation under the open-switch fault condition in the rectifier stage are proposed. An open-switch fault in the rectifier stage of a reverse matrix converter causes current distortions and voltage ripples in the system. Therefore, fault-tolerant control for open-switch faults is required to improve the reliability of a system. The proposed strategy determines the appropriate switching stages from among the remaining healthy switches of the converter. This is done based on reference currents or voltages. The performance of the proposed strategy is experimentally verified.

• 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.