A confidence-based software voter for safety-critical systems

Abstract

To tolerate software faults, N-Version Programming (NVP) and N-Modular Redundant (NMR) techniques are widely employed. In these techniques, N modules operate on the same data and send their outputs to a software voter. Since the voter is a single point of failure in the techniques, availability and safety are essential requirements. In this paper a confidence-based software voting technique is proposed. The proposed technique considers weight oscillation and confidence of each module to improve availability and safety of the voter. Evaluation results showed that availability and safety of confidence-based software voter in contrast with standard majority voter and adaptive majority voter has improved about 4.4%, 4.9%, and 5.8% for three error injection scenarios.

Coexistence of safety and security: Synchronized redundant system with security enhancements

“…Otherwise, when the voting is at a high level, the software voter is better, eg, connecting the voter to computers that will perform complex tasks . Generally, having a dedicated hardware to perform the voting is faster than a software voter is, but the software voter has more flexibility because it is easier to implement or change the voting method …”

“…Safety-critical systems need to tolerate faults and continue to operate normally; then errors must not occur, and faults should be masked to prevent the occurrence of errors. 4 Redundancy is used to hide the occurrence of failures from other processes. Moreover, the standard IEC-61508 3 mentions that redundancy is required to ensure safety.…”

“…7 Generally, having a dedicated hardware to perform the voting is faster than a software voter is, but the software voter has more flexibility because it is easier to implement or change the voting method. 4,8,9 According to the type of voting, the voter can be exact or inexact. The exact voter compares the inputs, and they must be equal to be considered as correct if one input is distinct not matter the difference the input is marked as incorrect.…”

“…To achieve reliability objectives in the system, the norms state that errors must not occur, and faults should be masked to prevent the occurrence of errors. 4 Redundancy is one of the masking techniques, which consists in performing the same task in multiple devices. The outputs of these devices are sent to the voter, and the voter FIGURE 1 Redundant system with distributed voters chooses the correct output.…”

Recursive Algorithm for Exhaustive Search of Possible Multiversion Software Realizations with the Choice of the Optimal Versions Set

“…The analysis is carried out by a decision-making unit. The process of decision-making is usually realized by a voting algorithm [11], [12]. During the implementation of N-version software, the voting algorithm is implemented after every modules versions implementation.…”