Modular TMR multiprocessor system

Chande, P.K.; Ramani, A.K.; Sharma, Pramod

doi:10.1109/41.20342

Cited by 20 publications

(6 citation statements)

References 8 publications

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“…TMR is one of the most popular hardware fault-tolerance methods. Errors generated by any single faulty module are masked using a simple voter [6], [15]. The TMR is useful for tolerating a single permanent fault or ITF.…”

Section: Ctfmentioning

confidence: 99%

“…The TMR is useful for tolerating a single permanent fault or ITF. Research on TMR systems is documented in many papers [6], [8]- [10], [15]. In [3], [4], [6], retry techniques using time redundancy are introduced in TMR to tolerate ITF more effectively.…”

Section: Ctfmentioning

confidence: 99%

“…Research on TMR systems is documented in many papers [6], [8]- [10], [15]. In [3], [4], [6], retry techniques using time redundancy are introduced in TMR to tolerate ITF more effectively. To tolerate CTF, [2] suggests task staggering and resynchronization in a 0018-9529/00$10.00 © 2000 IEEE TMR system.…”

Section: Ctfmentioning

confidence: 99%

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Task-scheduling strategies for reliable TMR controllers using task grouping and assignment

Kwak

Kim

2000

IEEE Trans. Rel.

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and Conclusions-Real-time computers are often used in embedded, life-critical applications where high reliability is important. A common approach to make such systems dependable is to vote on redundant processors executing multiple copies of the same task. The most popular redundant structure is Triple Modular Redundancy (TMR). The processors that make up such systems are subject not only to independently occurring permanent & transient faults, but to correlated transient faults, such as electromagnetic interference (EMI) caused by the operating environment. This paper proposes two new scheduling strategies for TMR computer-controllers. Both strategies can tolerate correlated faults as well as independent faults. These strategies, TMR-R (TMR with Rotated task group) and TMR-Q (TMR with Quintuple computation), are developed using task grouping and assignment. To evaluate the reliability of these strategies, a discrete-time Markov model for control systems is devised. Reliability equations for the TMR-R and TMR-Q are derived from state transitions of sampling intervals based on the Markov model. The reliability of these TMR is proved by comparing them with a conventional TMR, using numerical analysis. These proposed strategies are anticipated to be useful for control systems operating in harsh environments, such as controllers of airplanes or nuclear power plants.

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Section: Ctfmentioning

confidence: 99%

Section: Ctfmentioning

confidence: 99%

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Task-scheduling strategies for reliable TMR controllers using task grouping and assignment

Kwak

Kim

2000

IEEE Trans. Rel.

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“…In [22], an optimal TMR structure to recover from a transient fault was shown to extend significantly the lifetime of a small system in spite of its requirement of reliable voter circuits. The authors of [3] propdsed a modular TMR multiprocessor to increase reliability and availability by using a retry mechanism to recover transient faults, and switching between TMR and dual-processor modes to isolate a permanent fault. A simple multiple-retry policy (retry a pre-specified number of times)-also' used to discriminate a permanent fault-was employed there.…”

Section: Introductionmentioning

confidence: 99%

A time redundancy approach to TMR failures using fault-state likelihoods

Shin

Kim

1994

IEEE Trans. Comput.

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Failure to establish a majority among the processing modules in a triple modular redundant (TMR) system, called a TMR failure, is detected by using two voters and a disagreement detector. Assuming that no more than one module becomes permanently faulty during the execution of a task, Re-execution of the task on the Same Hardware (RSHW) upon detection of a TMR failure becomes a cost-effective recovery method, because 1) the TMR s p e m can mask the effects of one faulty module while RSHW can recover from nonpermanent faults, and 2) system reconfiguration-Replace the faulty Hardware, reload, and Restart (RHWR)-i s expensive both in time and hardware. We propose an adaptive Wovery method for TMR failures by "optimally" choosing eithp RSHW or RHWR based on the estimation of the costs involved. We apply the Bayes theorem to update the likelihoods of all possible states in the TMR system with each voting result. Upon detection of a TMR failure, the expected cost of RSHW is derived with these likelihoods and then compared with that of RHWR. RSHW will continue either until it recovers from the TMR failure or until the expected cost of RSHW becomes larger than that of RHWR. As the number of unsuccessful RSHW's increases, the probability of permanent fault@) having caused the TMR failure will increase, whicli will, in turn, increase the cost of RSHW. Our simulation results show that the proposed method outperforms the conventional reconfiguration method using only RHWR under various conditions.

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“…Fault tolerant systems have been studied for a long time, and many solutions have been proposed such as the insertion of codes for error correction [3] and the use of software [4] or hardware [5] redundancy. However, none of these solutions is able to cope with simultaneous faults and, when they are able to do so, the cost increase makes the solution impractical, or at least very expensive.…”

Section: Introductionmentioning

confidence: 99%

Evaluating Sigma-Delta Modulated Signals to Develop Fault-Tolerant Circuits

Schüler

Farenzena

Carro

Eleventh IEEE European Test Symposium (ETS'06)

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As microelectronics evolves smaller into the nanometric scale, external interferences starts to be harmful to the system expected behavior. As classical systems do not handle adequately faults caused by such sources, new topologies are proposed. Our present work proposes a solution for this problem consisting on the use of sigma-delta modulation in order to obtain a faulttolerance even in presence of multiple faults. This paper provides the mathematical analysis and demonstration to support the proposed approach.

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Modular TMR multiprocessor system

Cited by 20 publications

References 8 publications

Task-scheduling strategies for reliable TMR controllers using task grouping and assignment

Task-scheduling strategies for reliable TMR controllers using task grouping and assignment

A time redundancy approach to TMR failures using fault-state likelihoods

Evaluating Sigma-Delta Modulated Signals to Develop Fault-Tolerant Circuits

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