VOTING ALGORITHMS IN MULTIPLE ERROR SCENARIOS FOR REAL-TIME CONTROL APPLICATIONS
G. Latif-Shabgahi*, S. Bennett^ and J. M. Bass+
* Telematics Dept, Technology Faculty, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK
^ Automatic Control and Systems Eng. Department, The University of Sheffield Mappin Street, Sheffield, S1 3JD, UK
+ Chordiant Software International Inc., London, UK
Voting algorithms are used to arbitrate between the variant results in fault tolerant systems. Traditional voters produce incorrect outputs in multiple error conditions. This paper introduces a class of voters, called predictor voters, which can resolve some of the multiple error conditions. They use execution-time information of the system to select the most likely correct variant result as the voter output. Different versions of predictor voters are explained and their safety and availability performance in triple error scenarios are investigated. The experimental results show that predictor voters give safety behaviour between majority and median voters. Predictor voters with order three and above give higher availability than the median voter. Predictor voters are suitable for use in systems in which some incorrect outputs can be tolerated in order to maitain functionality over long period of time.
Keywords: Fault-Tolerance, Real-time System, Reliability Analysis, Safety Analysis, Prediction methods, and Transient errors
Session slot T-Th-M13: Real-Time Systems Issues/Area code 9d : Algorithms and Architectures for Real-Time Control

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