P. R. Lorczak, A. K. Caglayan, and D. E. Eckhardt, "A Theoretical Investigation of Generalized Voters for Redundant Systems," Proc. IEEE Fault-Tolerant Comput. Symp., pp. 444-451, 1989.  Home/Search   Document Not in Database   Summary   Related Articles   Check

.... fail consistent failures where all fault free processors perceive P i s failure uniformly [4] A suitable agreement algorithm under this fault model is the median voter which selects a middle value from an odd number of residues by eliminating those residue pairs differing by the greatest amount [7]. At the end of phase 2, all fault free processors correctly identify A i s status. 2.3 Problem Statement The overall control and diagnosis approach shown in Fig. 3 is modeled as a directed acyclic task graph G i consisting of vertices and edges representing tasks and precedence constraints, ....

P. R. Lorczak, A. K. Caglayan, and D. E. Eckhardt, "A Theoretical Investigation of Generalized Voters for Redundant Systems," Proc. IEEE Fault-Tolerant Comput. Symp., pp. 444-451, 1989.

....multiple parameters, we hope to cover many of these. Examples include distance agreement protocols and distance decision [13] which involve voting in multidimensional space; the generalization of commonly used voting techniques such as Formalized Majority Voter, Generalized Median Voter, etc. in [23]; and the adjudicators and adjudication functions [16] which are generalized concepts of voters and voting algorithms. The Consensus Service is a technique for constructing agreement protocols [17] Our research is not a theoretical attempt to provide a generalized voting service or notation ....

P. R. Lorczak, A. K. Caglayan, and D. E. Eckhardt. A theoretical investigation of generalized voters for redundant systems. In Proc. 19th IEEE Int. Symp. on Fault-Tolerant Computing, pages 444--451, 1989.

....is used to produce a final output value. Because the values used in 24 the arbitration have been pre screened, the selection algorithm and the overall approach is likely to be more effective. Cross comparison of the available version outputs is usually performed by means of a voting algorithm. Lorczak 89] presents four generalized voters for use in redundant systems: Formalized Majority Voter, Generalized Median Voter, Formalized Plurality Voter, and Weighted Averaging Techniques. The proposed generalization of the voting techniques is based on a framework of metric spaces 1 . By assuming the ....

....and the application. When all the weights are equal this technique becomes a mean selection technique. The weights can also be selected dynamically based on the pair wise distances of the version outputs [Broen 75] or the success history of the versions measured by some performance metric ( Lorczak 89] Gersting 91] Other voting techniques have been proposed. For example, Croll 95] proposed a selection function that always produces an acceptable output through the use of artificial intelligence techniques. Specifically, the voting system would behave like a majority or plurality voter ....

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Paul R. Lorczack, et al, A Theoretical Investigation of Generalized Voters for Redundant Systems, Digest of Papers FTCS-19: The Nineteenth International Symposium on Fault-Tolerant Computing, 1989, pp. 444 - 451.

....known accuracy bound from its argument. As the voting convergence function is a primary building block for redundancy management operations, we mention some common voting techniques and convergence functions used in practice where approximate agreement is required. Examples of generalized voters [21] include: formalized majority voter, generalized median voter, formalized plurality voter, and weighted averaging technique. Since a faulty processor may send different values to different processors, it is quite possible that due to receiving widely ranging values, a processor may differ by ....

P.R. Lorczak, A.K. Caglaya, D.E. Eckhardt, "A Theoretical Investigation of Generalized Voters for Redundant Systems." Proc. of FTCS--19, pp. 444--451, 1989.

....Note that while we have carried out this discussion under the hypothesis that all modules are expected to produce the same output, a more realistic (and more general) hypothesis is to consider that they must be equivalent (in some sense) rather than equal. Brilliant et al. [6] and Lorczak et al. [19] have investigated forms of equivalence relation that are appropriate for this purpose, and their application to modular redundancy. Voter F F 0 F 00 Gamma Gamma Gamma Gamma Gamma Gamma Gamma Gamma Gamma Gamma Gamma Gamma Gamma Gamma L: Figure 1: An ....

P. R. Lorczak, A. K. Koglayan, and D. E. Eckhardt. A theoretical investigation of generalized voters for redundant systems. In The 19th International Symposium on Fault-Tolerant Computing (FTCS 19), pages 444--451, 1989.

....are equal if a and b differ by less than tolerance e. If NVP MV, NVP CV or MLV make decisions based on non transitive equality relations, ambiguities may appear and a wrong answer may be selected as the correct one, or there may not be a consistent agreement. In both cases the system fails [16]. This tolerance effect can cause even systems of statistically independent versions to fail more often than the classical software fault tolerance theory would suggest. This paper discusses voting techniques that are based on the concept of fuzzy sets, fuzzy equivalence relations, and the l ....

....the answer from the set x 1 , x 2 , x 5 . However, without further modification, this approach has a serious limitation. For example, when the outputs are equi distant to a given fixed tolerance (x, x e , x 2e , x Ne ) the transitive closure will declare all outputs to be identical [16]. This may negate any benefits of the voting approach In order to avoid this problem, Lorczak proposed two voting techniques, Formalized Majority Voting (FMV) and Formalized Consensus Voting (FCV) 16] For an N version system, these voting techniques create N output subsets which are not ....

[Article contains additional citation context not shown here]

P. R Lorczak,. A.K. Caglayan, D.E. Eckhardt, "A Theoretical Investigation of Generalized Voters for Redundant Systems", Proc. 19th FTCS, Chicago, Illinois, June 1989, pp. 444-451.

....have been implemented under a rather restricted voting possibility, which is the majority voting. Such a restriction is hard to justify when one needs an agreement on sensor data in real time systems. Indeed, agreement among sensor data usually calls for voting results other than majority ones [15]. It is then necessary to design and implement fault tolerant systems for realtime applications under a highly unrestricted voting. Furthermore, to prevent undeterminism in computation caused by the process replications, costly explicit messages reordering and clock synchronisation mechanisms ....

Paul R. Lorczak, Alper K. Caglayan, and Dave E. Eckhardt, " A theoretical investigation of generalized voters," Proceedings of the 19th International Symposium on Fault-tolerant Computing, 1989, pp. 444451.

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