• KSTLE International Journal
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• 제4권2호
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• pp.37-42
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• 2003

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 a fault-tolerant magnetic bearing system for a turbo-molecular vacuum pump. The system can cope with the actuator/amplifier faults which are the most common faults in a magnetic bearing system. We implemented the existing fault-tolerant algorithms to experimentally prove the adequacy of the algorithms for industrial applications. As it turns out, the system can operate even with three simultaneously failing poles out of eight actuator poles.

• 동력기계공학회지
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• 제8권1호
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• pp.62-68
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• 2004

This paper describes a fault tolerant control in distributed PLC(Programmable Logic Controller) system to ensure reliability of controllers which have some faults simultaneously. First, the behavior of PLC is modeled as discrete expressions using Galois field. Then, we design the control laws for additional spare controllers to generate parity code with two dimensions. Finally, the algorithm for estimating normal output instead of abnormal output from the controllers with fault is suggested. Comparing to the traditional duplication method, the suggested method can reduce the number of spare controllers significantly to ensure control reliability. This method will be applied to an automatic system in order to increase reliability. Also, it can improve cost performance of the system.

• ETRI Journal
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• 제33권1호
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• pp.50-59
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• 2011

In the current very deep submicron technology era, fault tolerant mechanisms perform an essential function to cope with the effects of soft errors. To evaluate the effectiveness of the fault tolerant mechanism, reliability engineers use simulated fault injections using either saboteur modules or mutants in the simulation model. However, the two methods suffer from both inefficiency in the simulation mechanism and difficulties with the experimental setups. To overcome these inefficiencies, we propose the Verilog-based simulated fault injection (VFI) technique. VFI has the following advantages. First, modification of the design model is unnecessary. Second, the fault injection simulation procedure is simple and efficient. Third, various types of fault injection experiments can be performed. To evaluate the effectiveness of the proposed methodology, we developed a VFI environment using the ICARUS Verilog Simulator. From the experimental results, we were able to qualitatively evaluate the reliability of the target simulation models and to assess the effectiveness of the employed fault-tolerance mechanisms.

• 대한전기학회논문지:시스템및제어부문D
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• 제51권6호
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• pp.241-251
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• 2002

The effect of sensor faults in direct torque control(DTC) based induction motor drives is analyzed and a new Instrument fault detection isolation scheme(IFDIS) is proposed. The proposed IFDIS, which operated in real-time, detects and isolates the incipient fault(s) of speed sensor and current sensors that provide the feedback information. The scheme consists of an adaptive gain scheduling observer as a residual generator and a special sequential test logic unit. The observer provides not only the estimate of stator flux, a key variable in DTC system, but also the estimates of stator current and rotor speed that are useful for fault detection. With the test logic, the IFDIS has the functionality of fault isolation that only multiple estimator based IFDIS schemes can have. Simulation results for various type of sensor faults show the detection and isolation performance of the IFDIS and the applicability of this scheme to fault tolerant control system design.

• 제어로봇시스템학회논문지
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• 제19권9호
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• pp.822-826
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• 2013

In this paper, we propose an AFDO (Adaptive Fault Diagnosis Observer) and a fault tolerant controller for a class of nonlinear continuous-time system under the nonlinear abrupt actuator faults. Together with its estimation laws, the AFDO which estimates that the actuator faults is designed by using the Lyapunov analysis. Then, based on the designed AFDO, an adaptive sliding mode controller is proposed as the fault tolerant controller. Using Lyapunov stability analysis, we also prove the uniform boundedness of the state, the output and the fault estimation errors, and the asymptotic stability of the tracking error under the nonlinear time-varying faults. Finally, we illustrate the effectiveness of the proposed diagnosis method and the control scheme thorough computer simulations.

• 한국정보처리학회논문지
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• 제6권12호
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• pp.3662-3674
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• 1999

본 논문에서는 대용량 병렬처리를 위한, 결함허용 다중칩을 이용해서 제조된 어레이시스템에서 여분장치 최적화와 관련된 설계문제를 다룬다. 수율과 신뢰성을 고려한 최적의 비용효과적인 다중칩 설계를 위한 새로운 계량적 방법을 제안하고 결함허용 다중칩의 운영신뢰성에 미치는 잠재여분의 효과를 분석한다. 특히 불완전한 지원회로, 칩조립수율과 어레이위상의 문제들에 대하여 논한다. 광범위에 걸친 분석결과에 따르면 제안한 방법은 수율과 신뢰성을 고려한 대용량 병렬처리 응용분야에 사용되는 다중칩 어레이 설계에 기존방법보다 매우 효율적으로 적용 가능하다.

• 산업공학
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• 제23권1호
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• pp.68-77
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• 2010

Digital reactor protection system which consists of many identical modules, is fault- tolerant to provide high safety. The modules themselves including DSP(digital signal processing) card are also fault-tolerant in nature. This paper assesses the safety for being-designed digital reactor protection system of 2-out-of-4 G structure with lockout. Some interesting design alternatives are compared. Fault tree analysis for assessing system safety is performed by Relex software. The selected reactor protection system fully satisfies EPRIURD stipulation of mean failure time of 50 years.

• 한국항공우주학회지
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• 제33권12호
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• pp.54-60
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• 2005

본 논문에서는 비행체의 내고장 제어 기법을 다루고 있으며, 시간 지연 제어 이론에 근거한 내고장 제어 알고리듬을 제시한다. 시간 지연 제어는 부정확한 동특성을 다루는데 효과적인 방법이다. 내고장성을 위해 제안한 알고리듬의 가장 큰 장점은 실시간으로 갱신해야할 파라미터가 없으며 또한 고장에 대한 선행적인 정보를 필요로 하지 않는다. 제안한 기법은 출력 되먹임을 이용한다. 이에 따른 설계조건 및 안정성 조건을 제시하였다. 마지막으로 시뮬레이션을 통해 제시한 기법의 유효성을 검증하였다.

• 한국통신학회논문지
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• 제32권1B호
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• pp.22-30
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• 2007

본 논문에서는 분산 객체 관리의 편의성을 제공하고, 고장 발생시에도 안정된 서비스를 가능케 하는 고장포용 객체그룹(Fault-Tolerant Object Group, FTOG) 프레임워크를 제안한다. FTOG 프레임워크는 서비스 우선순위와 체크포인트 방법을 이용하여 두 가지의 고장 회복 방안을 제공하며 퍼지 기반의 부하 추론 과정을 통한 부하 분산을 수행하여 서비스 실행에서의 효율성을 높인다. 또한 가상의 홈네트워크 환경을 구성하고 FTOG 프레임워크를 적용하여 시뮬레이션을 통해 분산되어 있는 객체들의 관리 및 부하 분산 등 본 모델의 안정성 및 신뢰성을 검증하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.756-760
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• 2005

By development of a robot technology, personal robot is being developed very actively. Various infra-technologies are accumulated in hardware and software how by internal a lot of research and development efforts, and it is circumstance that actual commodity is announced. But, personal robot is applied to be acting near human, and takes charge of safety and connected directly a lot of works of home security, gas-leakage, fire-warning facilities, or/and etc. So personal robot must do safe and stable action even if any unexpected accidents are happened, important functions are always operated. In this paper, we are wished to show design structures for supporting fault-tolerant operation from our real-time robot middleware viewpoint. Personal robot, in being developed, was designed by module structure to do to interconnect and to interoperate among each module that is mutually implemented by each research facilities or company. Also, each modules can use appreciate network system that is fit for handling and communicating its data. To guarantee this, we have being developed a real-time network middleware, for especially personal robot. Recent our working is to add and to adjust some functions like connection management, distributed routing mechanism, remote object management, and making platform independent robot application execution environment with self-moving of robot application, for fault-tolerant personal robot.