Operational failure experience of fault-tolerant digital control systems

Paula, H.M.; Roberts, M.W.; Battle, R.E.

doi:10.1016/0951-8320(93)90004-i

Cited by 2 publications

(2 citation statements)

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“…The study also includes operator error and power supply failure as causes for system failure; since many robotic applications also require input from a human operator, these data were deemed appropriate for demonstration purposes. As in [2] we have separated the failure modes of the FT-DCS into five categories: output module failure (basic event output), failures caused by operator error (basic event operator), failures caused by software error (basic component software), power supply failures, and hardware failures (basic event hardware).…”

Section: System Analyzedmentioning

confidence: 99%

“…In order to make the system analysis more complete, we have included here a fault-tolerant digital control system necessary for the operation of the robot. Failure rates and coverage information for the controller are extrapolated from 112 [2], one of the few studies available which uses actual failure data as its source. Our figures come from the data on dualredundant processorltriple-redundant input module logic @UAL/TRIML) controllers.…”

Section: System Analyzedmentioning

confidence: 99%

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Analysis of robots for hazardous environments

Harpel

Dugan

Walker

et al.

Annual Reliability and Maintainability Symposium

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& CONCLUSIONS Reliability analysis of fault tolerant systems often ignores the small probability that a failure might not be detected or, if detected, may not be properly handled. The probability that the failure is detected and properly handled is called coverage. Inclusion of coverage in reliability analysis is especially important when analyzing critical systems, systems: which for some reason are not easily reparable, or systems whose failure can result in serious damage to the system or its surroundings. One example of a system which can cause such damage is a robot manipulator arm. Robots are being increasingly employed in remote and hazardous environments such as in space and in nuclear waste cleanup, and can exhibit a wild response to subsystem failure, damaging themselves and/or their surroundings. Addition of redundancy to such systems can increase their reliability by allowing continued operation in the presence of faults (provided that the fault is covered), an advantage in a system where repair is difficult or impossible. Coverage models have been used to analyze the behavior of fault-tolerant computer systems in the presence of faults, providing an estimate of the relative probability of an uncovered vs. a covered component failure (given that a fault has occurred) [l]. This paper extends the use of coverage models to the basic components of the joint of a robot and presents data utilizing the calculated coverage for a three-joint robot manipulator arm designed to operate in the plane.

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Section: System Analyzedmentioning

confidence: 99%

Section: System Analyzedmentioning

confidence: 99%