EVENODD 방법 기반 결함허용 사물인터넷 시스템 개발

우민우,박기현,안동혁 사단법인 인문사회과학기술융합학회 2017 예술인문사회융합멀티미디어논문지 Vol.7 No.3

The concept of Internet of Things (IoT) has been increasingly popular these days, and its areas of application have been broadened. However, if the data stored in an IoT system is damaged and cannot be recovered, our society would suffer considerable damages and chaos. Thus far, most of the studies on fault-tolerance have been focused on computer systems, and there has not been much research on fault-tolerance for IoT systems. In this study, therefore, a fault-tolerance method in IoT environments is proposed. In other words, based on the EVENODD method, one of the traditional fault-tolerance methods, a fault-tolerance storage and recovery method for the data stored in the IoT server is proposed, and the method is implemented on an oneM2M IoT system. The fault-tolerance method proposed in this paper consists of two phases – fault-tolerant data storage and recovery. In the fault-tolerant data storage phase, some F-T gateways are designated and fault-tolerant data are distributed in the F-T gateways’ storage using the EVENODD method. In the fault-tolerant recovery phase, the IoT server initiates the recovery procedure after it receives fault-tolerant data from non-faulty F-T gateways. In other words, an EVENODD array is reconstructed and received data are merged to obtain the original data. 사물인터넷의 개념은 계속 발전하고 있으며, 그 웅용 분야를 넓히고 있다. 그러나, 만약에 사물인터넷 시스템에 저장된 중요한 데이터가 손상되고 복구할 수 없다면, 우리 사회는 상당한 피해와 혼란을 겪게 될 것이다. 지금까지의 결함허용에 대한 연구는 주로 컴퓨터시스템에 대해서 대부분 이루어졌으며, 사물인터넷에 관한 연구는 극히 적었다. 따라서, 본 연구에서는, 사물인터넷 환경에서의 결함허용 방법을 제안한다. 즉, 기존의 EVENODD 결함 허용 방법에 기초하여, IoT 서버의 원본 데이터에 대한 결함허용 저장 및 복구 방법을 제안하고, 이를 oneM2M 기반 사물인터넷 시스템에 구현하였다. 본 연구의 결함 허용 방법은 두 단계(결함 허용 저장과 복구)로 나뉜다. 결함 허용 저장 단계에서는 F-T 게이트웨이를 지정하고 결함 허용 데이터를 F-T 게이트웨이들에게 EVENODD 방식으로 분산 저장한다. 결함 복구 단계에서는 정상적인 F-T 게이트웨이들로부터 결함허용 관련 데이터를 수신한 IoT 서버는 복구 절차를 수행한다. 즉, EVENODD 배열을 재구성하고 분할된 데이터들을 합병하여 원본 데이터를 생성하여 복구한다.

Fault-Tolerance Techniques in Cloud Storage : A Survey

Seyyed Mansur Hosseini,Mostafa Ghobaei Arani 보안공학연구지원센터 2015 International Journal of Database Theory and Appli Vol.8 No.4

In recent years, cloud computing is highly embraced and more organizations consider at least some type of cloud strategy and apply theming their business process. Since failure is probable in cloud data centers and access to cloud resources available is fundamental, evaluation and application of different fault-tolerance methods is inevitable. On the other hand, the increasing growth of cloud storage users motivated us to study fault-tolerance techniques, and their strengths and weaknesses. In this paper, after introducing the concept off ault-tolerance in the context of cloud computing, the fault-tolerant techniques are presented, and after introduction of some measures, a comparative analysis is provided.

서비스로봇의 신뢰성 향상을 위한 OPRoS 기반 Fault-tolerance 기법

안희준(Heejune Ahn),이동수(Dongsu Lee),안상철(Sang Chul Ahn) 제어로봇시스템학회 2010 제어·로봇·시스템학회 논문지 Vol.16 No.6

For commercial success of emerging service robots, the fault tolerant technology for system reliability and human safety is crucial. Traditionally fault tolerance methods have been implemented in application level. However, from our studies on the common design patterns in fault tolerance, we argue that a framework-based approach provides many benefits in providing reliability for system development. To demonstrate the benefits, we build a framework-based fault tolerant engine for OPRoS (Open Platform for Robotic Services) standards. The fault manager in framework provides a set of fault tolerant measures of detection, isolation, and recovery. The system integrators choose the appropriate fault handling tools by declaring XML configuration descriptors, considering the constraints of components and operating environment. By building a fault tolerant navigation application from the non-faulttolerant components, we demonstrate the usability and benefits of the proposed framework-based approach.

Active Fault Tolerant Control Scheme for Satellite Attitude Systems: Multiple Actuator Faults Case

Zhi-Feng Gao,Zepeng Zhou,Guoping Jiang,Mo-Shu Qian,Jin-Xing Lin 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.4

In this paper, an active fault tolerant control (FTC) design approach is proposed for the satellite attitude systems with exogenous disturbance and multiple actuator faults. Firstly, the nonlinear attitude system model of rigid satellite with multiple actuator faults is given. Next, an actuator fault diagnosis scheme, including a fault detection module and a fault estimation module, is given so as to detect the time of unknown actuator faults occurred and obtain their estimation values. Then, a terminal sliding mode-based fault tolerant attitude controller is designed using backstepping control technique, which guarantees that the closed-loop attitude systems of rigid satellite are asymptotically stable in the presence of multiple actuator faults. Numerical simulations illustrate the good performance of active FTC proposed in this study.

Fault-tolerant Trajectory Tracking Control of a Quadcopter in Presence of a Motor Fault

Davood Asadi,Karim Ahmadi,Seyed Yaser Nabavi 한국항공우주학회 2022 International Journal of Aeronautical and Space Sc Vol.23 No.1

As a part of emergency landing architecture for multi-rotor, a fault-tolerant trajectory tracking control strategy is proposed in this paper to control a quadcopter in case of a partial motor fault. The introduction of fault-tolerant strategy includes a lightweight fault detection and identification algorithm and a three-loop tracking controller. The lightweight fault detection and identification algorithm identifies the fault based on the controller outputs and the angular rates calculated by a discrete extended Kalman filter. The three-loop controller comprises a cascade structure of a discrete nonlinear adaptive algorithm in the inner-loop and a PID algorithm in the outer-loops of the controller structure. To have more realistic simulations, the gyroscopic effects of rotors and the airframe drag terms are considered in modeling as the model uncertainty. The simulation results demonstrate that the proposed fault-tolerant controller can effectively control the quadcopter in presence of partial motor fault, model uncertainties, and sensor noises. The results also demonstrate the effect of fault detection time delay on the overall control performance.

Integration of Fault Detection, Isolation and Switching Control for Fault Tolerant Control of Nonlinear Systems

In Soo Lee,Gordon K. Lee 한국정보기술학회 2007 한국정보기술학회논문지 Vol.5 No.2

This paper presents a fault tolerant control architecture using fault diagnosis and switching functions. The fault tolerant control system consists of a fault detection part to sense the faults, a fault isolation part to identify the types of faults that have occurred and a bank of compensators with switching for the control part. In the proposed method, the fault is detected when the errors between the nonlinear system and the neural network (NN) nominal system output cross a predetermined threshold. Once a fault in the system is detected, the fault classifier based on the NN isolates the fault. These results are fed into a controller block that selects an appropriate compensation scheme to handle the fault. Simulation results demonstrate the effectiveness of the proposed fault tolerant control method for nonlinear systems.

Fault-Tolerant Design for Advanced Diverse Protection System

오양균,정진권,이창재,이윤희,백승민,이상정 한국원자력학회 2013 Nuclear Engineering and Technology Vol.45 No.6

For the improvement of APR1400 Diverse Protection System (DPS) design, the Advanced DPS (ADPS) has recently beendeveloped to enhance the fault tolerance capability of the system. Major fault masking features of the ADPS compared withthe APR1400 DPS are the changes to the channel configuration and reactor trip actuation equipment. To minimize the faultoccurrences within the ADPS, and to mitigate the consequences of common-cause failures (CCF) within the safety I&Csystems, several fault avoidance design features have been applied in the ADPS. The fault avoidance design features includethe changes to the system software classification, communication methods, equipment platform, MMI equipment, etc. Inaddition, the fault detection, location, containment, and recovery processes have been incorporated in the ADPS design. Therefore, it is expected that the ADPS can provide an enhanced fault tolerance capability against the possible faults withinthe system and its input/output equipment, and the CCF of safety systems. For the improvement of APR1400 Diverse Protection System (DPS) design, the Advanced DPS (ADPS) has recently been developed to enhance the fault tolerance capability of the system. Major fault masking features of the ADPS compared with the APR1400 DPS are the changes to the channel configuration and reactor trip actuation equipment. To minimize the fault occurrences within the ADPS, and to mitigate the consequences of common-cause failures (CCF) within the safety I&C systems, several fault avoidance design features have been applied in the ADPS. The fault avoidance design features include the changes to the system software classification, communication methods, equipment platform, MMI equipment, etc. In addition, the fault detection, location, containment, and recovery processes have been incorporated in the ADPS design. Therefore, it is expected that the ADPS can provide an enhanced fault tolerance capability against the possible faults within the system and its input/output equipment, and the CCF of safety systems.

Fault-Tolerant Steer-By-Wire 제어 시스템의 개발

김재석(Jaesuk Kim),황운기(Woongi Hwang),이운성(Woon-Sung Lee) 한국자동차공학회 2006 한국 자동차공학회논문집 Vol.14 No.5

The Steer-By-Wire (SBW) system replaces complex mechanical linkages of the current steering system with electric motors, sensors, and electronic control units. However, the SBW system should guarantee its safety and reliability before commercialization, and therefore, a reliable and robust fault-tolerant technology has to be implemented. This paper proposes a fault-tolerant control algorithm for the SBW system. Based on careful analysis on propagation effects of sensor faults, a reliable fault-tolerant control strategy has been developed. The fault-tolerant controller consists of a fault detection part that monitors and detects faults in the steering wheel and road wheel sensors, and a reconfiguration part that switches to normal sensor signal based on fault detection information. It has been demonstrated by simulation that the proposed algorithm detects sensor faults accurately and enables reliable steering control under various dynamic fault situations.

Fault-weighted quantification method of fault detection coverage through fault mode and effect analysis in digital I&C systems

Cho, J.,Lee, S.J.,Jung, W. North-Holland Pub. Co 2017 Nuclear engineering and design Vol.316 No.-

<P>The one of the most outstanding features of a digital I&C system is the use of a fault-tolerant technique. With an awareness regarding the importance of thequantification of fault detection coverage of fault-tolerant techniques, several researches related to the fault injection method were developed and employed to quantify a fault detection coverage. In the fault injection method, each injected fault has a different importance because the frequency of realization of every injected fault is different. However, there have been no previous studies addressing the importance and weighting factor of each injected fault. In this work, a new method for allocating the weighting to each injected fault using the failure mode and effect analysis data was proposed. For application, the fault-weighted quantification method has also been applied to specific digital reactor protection system to quantify the fault detection coverage. One of the major findings in an application was that we may estimate the unavailability of the specific module in digital I&C systems about 20-times smaller than real value when we use a traditional method. The other finding was that we can also classify the importance of the experimental case. Therefore, this method is expected to not only suggest an accurate quantification procedure of fault-detection coverage by weighting the injected faults, but to also contribute to an effective fault injection experiment by sorting the importance of the failure categories. (C) 2017 Elsevier B.V. All rights reserved.</P>

Fault tolerance for PWM rectifiers based on basic voltage space vector model

Chao Sun,Yingning Qiu 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.7

A new basic voltage space vector model-based fault tolerance method from new perspective of vector reconstruction for generator side converter open circuit faults is proposed in this paper. In the space vector model, changes of voltage space vectors under single and multiple switch open-circuit fault conditions are summarized in mathematical expressions. The corrected voltage space vectors under fault conditions are essentially linear superpositions of normal voltage space vectors and the changes introduced by their corresponding faulty switches. The new fault tolerance method, which is developed based on a basic voltage vector model, uses reconstructed basic voltage space vectors to compensate the reference voltage vector. It realizes full-scale fault-tolerant compensation. The feasibility and superiority of the proposed fault-tolerant method are tested and compared on an experimental platform. The achieved superior system performance of the proposed fault tolerance method sufficiently demonstrates its effectiveness as well as the voltage vector deviation principle presented in this paper. It provides important insights into the fault tolerance control of power converters.