Complete disagreement in redundant real-time control applications

摘要

Redundant application algorithm "variants" are used to minimise errors in fault-tolerant real-time control systems. Voting algorithms arbitrate between variant results to select a single, hopefully correct, output. Both variants and voting algorithms can be implemented in either hardware or software. The behaviour of voting algorithms in multiple error scenarios is considered in this paper. Complete disagreement is defined as those cases where no two variant results are the same. A novel algorithm for real-time control applications, the smoothing voter, is introduced and its behaviour compared with previously published algorithms. Software implemented error-injection tests, reported here, show that the smoothing voter achieves a comromise between the result selection capabilities of the median voter and the safety features of the majority voter.