Automotive Functional Safety Compliance Requirements with ISO 26262: HW Architectural Metrics with an Example

Abstract

The newly released automotive safety standard ISO 26262 entitled ‘Road vehicles—Functional Safety’ gives the guidelines to demonstrate safety compliance of a product design. The standard describes the safety implementation process considering the total product life cycle. Based on the hazard and risk analysis carried out on the functionality of an item, the functional safety requirements are derived. For each of these functional safety requirements the technical safety requirements are specified with respect to Hardware and Software design. The standard has several requirements in order to prove the safety compliance with respect to Hardware and software design. In this paper one of the requirements in the hardware design which is known as HW Architectural metrics and Probabilistic Metric for random Hardware Failures is discussed. This is a quantitative assessment of a design with respect to technical safety requirements. The merits of each of these calculations are demonstrated using a simple example of a solenoid valve driver control circuit. The paper also discusses certain challenges in carrying out these analyses.