What is functional safety?
Implementing Safety Principles for Electrical/Electronic Systems to avoid the absence of unreasonable risk due to hazards caused by malfunctioning behaviour of E/E systems.
An Electrical/Electronic system can be broken down into three parts, of which functional safety is a critical component. It consists of three categories.
- Reliability, in that the system should work as it was designed to respond to a command and not fail.
- Availability, so that response time is quick.
- Safety means the system will respond to a failure in such a way as to not cause any injuries. While it is impossible to guarantee absolute safety, it is designed to bring the risk down as much as possible.
The safety principles for electronics are first practised in the aerospace, medical nuclear and rail industries.
Why ISO 26262?
- Expanding on IEC1508, ISO 26262 defines four Automotive Safety Integrity Levels (ASIL) of A, B, C or D, with D having the most safety-critical processes and strictest testing regulations.
- ASIL Quality Management (QM) refers to components that just require standard quality management processes. As you can see from the diagram above, different components inside a vehicle require different levels, depending on applications.
- The standard also differs from IEC1508 in that it understands that not all errors will lead to an accident, but there must be a way to recognize a failure and move to a ‘fail safe’ operation. For example, let us consider a windshield wiper system. The safety analysis will determine the effects that loss of wiper function can have on the visibility of the driver. The ASIL gives guidance for choosing the adequate methods for reaching a certain level of integrity of the product. This guidance is meant to complement current safety practices. Current automobiles are manufactured at a high safety level and ISO 26262 is meant to standardize certain practices throughout the industry.
– Article contributed by Jaleel Ahamad