Toward Effective Reliability Requirement Assurance for Automotive Functional Safety

Automotive functional safety requirement includes response time and reliability requirements learning from the functional safety standard ISO 26262. These two requirements must be simultaneously satisfied to assure automotive functional safety requirement. However, increasing reliability increases the response time intuitively. This study proposes a method to find the solution with the minimum response time while assuring reliability requirement. Pre-assigning reliability values to unassigned tasks by transferring the reliability requirement of the function to each task is a useful reliability requirement assurance approach proposed in recent years. However, the pre-assigned reliability values in state-of-the-art studies have unbalanced distribution of the reliability of all tasks, thereby resulting in a limited reduction in response time. This study presents the geometric mean-based non-fault-tolerant reliability pre-assignment (GMNRP) and geometric mean-based fault-tolerant reliability pre-assignment (GMFRP) approaches, in which geometric mean-based reliability values are pre-assigned to unassigned tasks. Geometric mean can make the pre-assigned reliability values of unassigned tasks to the central tendency, such that it can distribute the reliability requirements in a more balanced way. Experimental results show that GMNRP and GMFRP can effectively reduce the response time compared with their individual state-of-the-art counterparts.