Quantitative analysis methodology in safety-critical microprocessor applications

In this paper, a quantitative methodology to be considered in safety-critic al microprocessor applications is proposed. Some important aspects that mus t be considered in safety analysis work are discussed. We discuss how to ev aluate the dangerous detectable and undetectable system failure rates in a single microprocessor board and the mean time to unsafe failure (MTTUF) of a critical system. The proposed methodology is finally applied to a practic al system which employs a triple modular redundancy (TMR) architecture. The results obtained by employing this methodology are extremely relevant, esp ecially to those aspects related to the impact of the computational blocks in the final safety integrity level (SIL) of a critical system. In this pap er, we also consider how the software can influence the evaluation of the f ault cover factor, another important aspect in safety analysis work. (C) 20 01 Elsevier Science Ltd. All rights reserved.