The word 'safety' is subject to various different interpretations. However, when applied to modern automobile design it can generally be categorized using the following structure:
- Passive safety: Assuming that an accident is effectively inevitable, the aim of passive safety mechanisms is to minimize the severity of that accident. The passive safety elements found within a vehicle include seatbelts, crumple zones, etc.
- Active safety: The systems that are concerned with active safety (based on the knowledge of the current state of the vehicle) will aim to avoid accidents altogether in addition to the minimization of its effects if an accident occurs. Seatbelt pre-tensioning, airbag deployment, predictive emergency braking, anti-lock braking systems and traction control are all examples of this.
- Functional safety: This focusses on ensuring that all of the electrical and electronic systems (such as power supplies, sensors, communication networks, actuators, etc), including (but not limited to) all active safety related systems, function correctly. Functional safety is dealt with by the ISO-26262 standard (published in November 2011).
It is important to state from the beginning that functional safety does not mean that there is no risk of a malfunction taking place - instead, functional safety implies the absence of unacceptable risk due to hazards caused by malfunctioning behavior of electrical and electronic systems.
Fig. 1: Translation from functional safety goals to hardware design, with associated validation & verification. For higher resolution click here .
Origins of ISO-26262
The basis of the ISO-26262 standard resides in the more generic IEC- 61508, which has a broad field of application (industrial process, control and automation, as well as oil/gas, nuclear, etc). ISO-26262 has been built on the IEC-61508, but is totally dedicated to the automotive sector - more precisely its application is limited to safety-related electrical and electronic systems installed in series production passenger cars with a maximum gross weight of 3.500 kg. The first draft release surfaced in 2009, resulting in