• Journal of Power Electronics
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• v.6 no.1
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• pp.8-17
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• 2006

In this paper, we propose a fault-tolerant control system for the position control and vibration suppression of a flexible arm robot. The proposed control system has a strain gauge sensor signal observer based on a reaction force observer and detects a fault by monitoring an estimated error. In order to improve the estimation accuracy, the plant parameters included in the sensor signal observer are updated by using the strain gauge sensor signal in normal time through the adaptive law. After fault detection, the proposed control system exchanges the faulty sensor signal for the estimated one and switches to a fault mode controller so as to maintain the stability and the control performance. We confirmed the effectiveness of the proposed control system through several experiments.

• Journal of Information Processing Systems
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• v.18 no.6
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• pp.755-762
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• 2022

The existing electrical engineering design method and the dynamic objective function in the application process of automatic control system fail to meet the unbounded condition, which affects the control tracking accuracy. In order to improve the tracking control accuracy, this paper studies the electrical engineering design method based on neural network and the application of automatic control system. This paper analyzes the structure and working mechanism of electrical engineering automation control system by an automation control model with main control objectives. Following the analysis, an optimal solution of controllability design and fault-tolerant control is figured out. The automatic control power coefficient is distributed based on an ideal control effect of system. According to the distribution results, an automatic control algorithm is based on neural network for accurate control. The experimental results show that the electrical automation control method based on neural network can significantly reduce the control following error to 3.62%, improve the accuracy of the electrical automation tracking control, thus meeting the actual production needs of electrical engineering automation control system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.9
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• pp.46-53
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• 2007

The link-fault recovery in the normal Ethernet bridged networks has relied on the Spanning Tree Protocol(STP) or Rapid STP. However, STP can not offer fast error recovery which is needed real-time services such as aircraft. In this paper, we compare automatic protection switching(APS) providing fault-tolerant function in the BcN back bone system with Avionic Full Duplex Switched Ethernet(AFDX) which is recently equipped in the A380 for Airbone Databuses. Also, we propose a link-bypass scheme for improving fault-tolerant performance of the AFDX by connecting switches and bypass fault section when a fault is originated on the link. For comparing and verifying the performance of proposed scheme, we simulated Ethernet, AFDX, APS and proposed AFDX with link-bypass scheme using NS-2. The proposed AFDX with link-bypass scheme can be applied to aircrafts, BcN backbone networks and industrial automatic networks.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.1341-1344
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• 2006

임베디드 시스템의 신인도(Dependability)를 확보하기 위해 하드웨어적으로 여분을 두는 결함 허용(Fault-tolerant) 기법을 적용하는 것은 임베디드 시스템의 설치공간, 비용 및 전원 공급의 부족 등의 이유로 무리가 있다. 본 논문에서는 소프트웨어 결함 허용 기법의 일종인 시간 여분(Time-redundancy) 개념을 적용한 Extended Temporal Error Detection (E-TED) 기법을 연구하였으며, 실험을 통해 제안한 E-TED 기법이 기존의 TED 기법에 비해 데이터 오류의 감지 확률이 높은 것을 확인하였다.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.665-667
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• 1999

An adaptive algorithm is presented for diagnosis of actuator faults. The concept of unknown input decoupling is combined with an adaptive observer, leading to an adaptive diagnostic observer, which has the robustness property in the presence of an unmeasurable term such as uncertainties. The observation error equation for the adaptive diagnostic observer does not depend on the effect of uncertainties and used to construct an adaptive diagnostic algorithm that provides the estimates of the gains of actuators, which can be obtained directly via the use of the augmented error technique. The simulation results indicate that the proposed algorithm is more realistic in the sense that better robustness properties can be assured without knowledge about uncertainties and is potentially useful in the development of a fault tolerant control system.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.572-578
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• 2008

As the railway transportation is getting faster and its operation speed has increased rapidly, its signal control has been complicated. For real time signal processing it is very important to prohibit any critical error from causing the system to malfunction. Therefore, handling complicated signals effectively while maintaining fault-tolerance capability is highly expected in modern railway transportation industry. In this paper, we suggest an SoC (Sytem-on-Chip) design method to integrate these complicated signal controlling mechanism with fault tolerant capability in a single chip. We propose an SoC solution which contains a high performance 32-bit embedded processor, digital filters and a PWM unit inside a single chip to implement ATO's, ATC's, ATP's and ATS's digital signal-processing units. We achieve an enhanced reliability against the calculation error by adding fault tolerance features to ensure the stability of each module.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.674-677
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• 2009

반도체 기술에 발달로 SoC, MPSoC와 같은 기술이 주목을 받고 있다. 이와 함께 soft error의 증가, 설계복잡도와 같은 문제점이 나타나고 있다. 본 논문은 FT_ARM(Fault Tolerant ARM)을 설계하여, soft error에 대응 하고자한다. 또한 오류주입 시뮬레이션을 통해 설계한 FT_ARM의 성능을 비교한다.

• Journal of KIISE:Software and Applications
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• v.29 no.1_2
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• pp.20-29
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• 2002

The composite stock cutting problem is to allocate rectangular and/or irregular patterns onto a large composite stock sheet of finite dimensions in such a way that the resulting scrap will be minimized. In this paper, the distributed simulated annealing with the new cost error tolerant spatial decomposition is applied to the composite stock cutting problem in MPI environments. The cost error tolerant scheme relaxes synchronization and chooses small perturbations on states asynchronously in a dynamically changed stream length to keep the convergence property of the sequential annealing. This paper proposes the efficient data structures for representation of patterns and their affinity relations and also shows how to determine move generations, annealing parameters, and a cost function. The spatial decomposition method is addressed in detail. This paper identifies that the final quality is not degraded with almost linear speedup. Composite stock shapes are not constrained to convex polygons or even regular shapes, but the rotations are only allowed to 2 or 4 due to its composite nature.

• Journal of Satellite, Information and Communications
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• v.12 no.4
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• pp.42-49
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• 2017

Delay- and Disruption-Tolerant Network (DTN) has been considered as a key technology to overcome main challenges in interplanetary communications such as an intermittent connectivity and high bit error rates. The lack of end-to-end connectivity between source and destination results in long and variable delays and data loss, hence the Internet Protocols cannot operate properly in such environments because it requires an end-to-end connectivity. The DTN, which utilizes 'store-and-forward' message passing scheme between nodes, can overcome the lack of end-to-end connectivity in Interplanetary Network (IPN). In this paper, DTN is applied to 3-hop relay IPN, where messages are transmitted from Earth ground station to Lunar lander through Earth satellite and Lunar orbiter. ONE simulator is used to reflect the real environment of IPN and an efficient resource management method are analyzed to guarantee the message delivery by optimizing a message TTL (Time to Live), buffer size and message fragmentation.

• Journal of KIISE:Information Networking
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• v.29 no.5
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• pp.562-572
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• 2002

Distributed object technologies have become popular in developing distributed systems. Although such middleware platforms as DSOM, DCOM, CORBA and Java RMI ease the development of distributed applications, they do not directly improve the reliability and the availability of these applications. Because the task of developing fault-tolerance techniques for distributed object paradigms is often complicated and error-prone, there is a great need for a development toolkit that enhances the reliability and the availability of distributed objects. In this paper, we propose a fault-tolerant distributed middleware system based on RMI, called IMMORTAL. We use a log-based rollback-recovery mechanism for supporting reliable distributed computing. Through a series of experiments, we observe that benchmark applications on the IMMORTAL tolerate hardware and software failures and evaluate its performance and scalability.