A novel family of weighted average voters for fault-tolerant computer control systems

Fault masking is a widely used strategy for increasing the safety and reliability of computer control systems. The approach uses some form of voting to arbitrate between the results of hardware or software redundant modules for masking faults. Several voting algorithms have been used in fault tolerant control systems; each has different features, which makes it more applicable to some system types than others. This paper introduces a novel family of weighted average voters suitable for redundant sensor (and other inertial measurement unit) planes, at the interface level, of control systems. It uses two tuneable parameters, each with a ready interpretation, to provide a flexible voting performance when using the voter in different applications. The weight assignment technique is transparent to the user because the impact of the degree of agreement between any voter input and the other inputs is directly reflected in the weight value assigned to that input. The voter can be tuned to behave as the well-known inexact majority voter that is generally used in safety-critical control systems at different voting planes. We evaluated the performance of four versions of the novel voter through a series of fault injection experiments, and compared the results with those of the well-known Lorczak´s weighted average voter. The experimental results showed that the novel voter gives more correct outputs (1%–12% higher reliability) than the Lorczak´s voter in the presence of small permanent and transient errors. With large errors, lower-order versions of the novel voter give better performance than the ones with higher orders.