What is Functional Safety?

Every modern automobile is equipped with airbags system to protect you and your passengers in an event of a car crash. Now, if a sensor in the system fails? Would you expect this malfunctioning behaviour of a single sensor to cause the airbags to deploy inadvertently. Most likely, your answer is no! To design a system that performs its functions as intended and at the same time, any malfunction in the system does not lead to safety hazards is the goal of the engineers.

The question is, how do engineers design systems to ensure they perform their intended functions. In this brief explainer, we’ll delve into what functional safety is in the context of the automotive industry.

Functional Safety in Automotive Systems

Functional safety, as defined by ISO 26262, is the absence of unreasonable risks due to hazards caused by malfunctioning behaviour of the electrical/electronic systems (including electrical, electronic or programmable electronic elements). It ensures that systems are free from unacceptable risk of injury or damage. The system functions must be developed to an acceptable level of safety integrity by implementing additional design measures such as architectural constrains, diverse hardware (or software) implementation, additional monitoring etc.

Understanding ISO 26262

ISO 26262 is intended to be applied to safety-related systems that include one or more electrical and/or electronic (E/E) systems. It focuses on preventing hazards caused by system malfunctions and ensuring that systems perform their functions safely even when faults occur.

ISO 26262 is a standard ensuring the functional safety of electronic and electrical systems in vehicles, amid the push for automation and efficiency. ISO 26262 is a functional safety standard derived from the parent standard IEC 61508, like many others such as: ISO 14971 (Medical Devices), EN 5021x (Railway Systems), IEC 61511 (Process Industry) etc.

ISO 26262 also defines Management of Functional Safety that establishes essential requirements to ensure automotive systems are systematically designed, managed, and maintained for functional safety throughout their lifecycle. Part 2 of the ISO 26262 addresses both project-independent safety management and project-specific management activities across all development phases (from concept and design to production, operation, and finally decommissioning).

Part 2 guides organizations in implementing structured processes, emphasizing a strong safety culture, including requirements specification, design, integration, and validation, to mitigate potential safety risks in real-world applications of the product and achieve functional safety.

Functional Safety Life-Cycle

A typical functional safety lifecycle, when ISO 26262 is followed, starts with a thorough Hazard Analysis and Risk Analysis (HARA) to identify potential malfunctions and their impact on safety to derive safety goals. These goals are the top-level safety requirements for the intended/designed functions of the system to ensure the vehicle stays in a safe operating state.

The development process should follow a V-model approach, integrating safety requirements throughout the product’s lifecycle. Detailed technical safety requirements are then derived, such as a sensor‘s accuracy and response times. Followed by rigorous verification and validation processes, including hardware and software testing. Integrating the safety life-cycle process early in the vehicle’s development is key to achieving functional safety. This ensures compliance with ISO 26262, thereby meeting the state of the art safety standards, minimising the risk of harm, and enhancing passenger protection.

Functional Safety Assessment based on ISO 26262 | 2018

Conclusion

Functional safety ensures that electrical and electronic systems in vehicles have safety measures in place to mitigate potential risks of damage or injuries. By adhering to ISO 26262, automotive engineers can design systems with high safety integrity to prevent harm in the event of failures. This meticulous approach to safety is what keeps us secure on the road, making functional safety a critical aspect of modern automotive design.

If you have been following, ISO 26262 and IEC 61508 considers only electrical/electronic (E/E) systems. What if the function and system implementation is not only through E/E elements, rather by diverse elements ranging from electro-mechanical elements to ones that involve human intervention? The safety process then falls under the broader framework of System Safety, you can find more details in our post on "What is System Safety?"