• ETRI Journal
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• v.33 no.1
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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.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.1
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• pp.59-70
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• 2022

In this paper, we proposed an active fault tolerant control (AFTC) method for the position control of a quadrotor with complete loss of effectiveness of one motor. We obtained the dynamics of a quadrotor using Lagrangian equation without small angle assumption. For detecting the fault on a motor, we designed a fault detection module, which consists of the fault detection and diagnosis (FDD) module and the fault detection and isolation (FDI) module. For the FDD module, we designed a nonlinear observer that observes the states of a quadrotor based on the obtained dynamics. Using the observed states of a quadrotor, we designed residual signals and set the appropriate threshold values of residual signals to detect the fault. Also, we designed an FDI module to identify the fault location using the designed additional conditions. To make a quadrotor track the desired path after detecting the fault of a motor, we designed a fault tolerant controller based on the multiple sliding surface control (MSSC) technique. Finally, through simulations, we verified the effectiveness of the proposed AFTC method for a quadrotor with complete loss of effectiveness of one motor.

• Journal of KIISE:Information Networking
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• v.31 no.3
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• pp.335-346
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• 2004

In this paper, we present a high-performance fault-tolerant switching networks using a deflection self-routing scheme, and present fault-diagnosis method for the network. We use the facts: 1) Each stage of the Banyan network is arrayed as the sequences of a Cyclic group of SEs. 2) There is the homomorphism between adjacent stages from a view of self-routing, so that all of each Cyclic group is the subgroup of the Cyclic group in the next stage, and there are factor groups due to such subgroup and homomorphism. We provide high-performance fault-tolerant switching networks of which the all links including augmented links are used as the alternate links detouring faulty links. We also present the fault diagnosis scheme for the proposed switching network that provide multiple paths for each input-output pair.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.732-732
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• 2006

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.6
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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.

• 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 the Korean Society for Aeronautical & Space Sciences
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• v.33 no.12
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• pp.54-60
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• 2005

In this paper, fault tolerant control for aircraft is being discussed. The authors propose a fault tolerant control algorithm based on time delay control. Time delay control is an effective method to deal with unknown dynamics. The proposed algorithm has no parameter to be updated and needs no prior information of faults. These are the primary advantages of the proposed method. The algorithm uses output feedback. The design and the stability condition are presented by following the existing proof. The proposed algorithms are verified by simulation examples.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1B
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• pp.22-30
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• 2007

In this paper, to achieve consistency maintenance as well as stable service execution, we build a Fault-Tolerant Object Group framework that provides both of the group management service and the load scheduling service. The group management service supports the object management such as registration and authentication, and provides two schemes for failure recovery using the service priority and the checkpointing. In the load scheduling servile, we improve the effectiveness of service execution through the reasoning process of object loads based on the ANFIS architecture. The effectiveness in the performance of the developed framework is validated through a virtual home-network simulation based on the FTOG framework.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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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.

• International Journal of Control, Automation, and Systems
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• v.6 no.3
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• pp.351-363
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• 2008

This paper is concerned with tasking and guidance of networked airborne sensors to achieve fault-tolerant sensing. The sensors are coordinated to locate hostile transmitters by intercepting and processing their signals. Faults occur when some sensor-carrying vehicles engaged in target location missions are lost. Faults effectively change the network architecture and therefore degrade the network performance. The first objective of the paper is to optimally allocate a finite number of sensors to targets to maximize the network life and availability. To that end allocation policies are solved from relevant Markov decision problems. The sensors allocated to a target must continue to adjust their trajectories until the estimate of the target location reaches a prescribed accuracy. The second objective of the paper is to establish a criterion for vehicle guidance for which fault-tolerant sensing is achieved by incorporating the knowledge of vehicle loss probability, and by allowing network reconfiguration in the event of loss of vehicles. Superior sensing performance in terms of location accuracy is demonstrated under the established criterion.