3 Key Concepts and Principles of Automotive Functional Safety

Automotive Functional Safety is one of the most critical aspects of modern automotive engineering. This process refers to the ability of an electronic system or component to perform the intended function in a safe manner. This includes systems that control braking, steering, and other safety critical functions. Functional Safety is a process that involves the identification of potential hazards in a vehicle, the assessment of the risks associated with these hazards, and the design and development of the safety measures to mitigate these risks. The safety measures developed are aimed at reducing the likelihood of accidents or injuries caused by the vehicle or systems and functions of the vehicle.

Automotive Functional Safety is based on a set of concepts and principles, including:

Hazard and Risk Analysis (HARA): HARA is the process of identifying potential hazards and assessing the associated risks in the design and development of vehicles. HARA helps to identify potential failure modes and potential consequences, and to determine the appropriate measures to mitigate the associated risks.

Safety Requirements: These are the systems level requirements that must be met by a safety function to achieve the required Safety Integrity Level. Safety requirements are derived from the HARA and are used to guide the design and development of safety functions.

Safety Functions: These are the functions within a vehicle that are critical to safe operation. Safety functions are designed to prevent or mitigate the consequences of a potential hazard in the event of a system failure.

Automotive Safety Integrity Level (ASIL): ASIL is a risk classification scheme as defined by the Automotive Functional Safety Standard ISO 26262 for road vehicles. As per ISO26262 Part 3, ASIL is determined by the Severity (S), Exposure (E), and the Controllability (C). Severity has four classes ranging from no injuries (S0) to life-threatening injuries (S3). Exposure has five classes ranging from incredibly unlikely (E0) to the highly probable (E4). Controllability also has four classes ranging from controllable in general (C0) to uncontrollable (C3). A combination of the highest hazards (S3 + E4 + C3) can result in an ASIL D classification for that hazardous event. There are four ASIL levels: ASIL A, ASIL B, ASIL C, and ASIL D, where ASIL A is the lowest safety integrity level and ASIL D is the highest one.

Automotive systems like Electric Power Steering (EPS) or Integrated Brake Control (IBC) systems are required to be an ASIL D functions due to the risks associated with their failure. Conversely, brake lights or headlights are generally an ASIL A function.

Verification and validation: These are the processes of testing and validating the safety mechanisms to confirm that the mechanisms meet the safety requirements to achieve the required Safety Integrity Level.

Historically, the automotive industry has relied on mechanical systems to provide the vehicle safety. However, as vehicles become more and more complex and interconnected, the use of electronic and software-based systems becomes more prevalent. These electronic and software-based systems can be more effective and efficient, but the systems also present unique challenges in terms of addressing Functional Safety.