As more and more types of high-tech products are becoming ubiquitous, analysts and journalists can’t seem to get enough of reporting on the many ways technology is changing our lives. One often overlooked aspect of this change, however, is the increasing focus on functional safety and what it means for product developers.
With the convergence between health-related lifestyle products and medical devices, and the fast development of autonomous and assisted driving, it is safe to say that we’re placing our lives in the hands of technology more than ever. Governments and other regulatory bodies are following up on this change by tightening requirements on product safety, reliability, and security. Functional safety is becoming a crucial aspect for developers of all sorts of products worldwide.
A growing number of companies are starting to understand the competitive advantage that expertise in functional safety means, while others are new to these requirements and are struggling to build functional safety into their product engineering activities that so far lacked this aspect.
What is Functional Safety?
In the context of functional safety in product development, safety is defined as the absence of unreasonable risk. While some risk will always be present and cannot be eliminated, developers are applying a systematic approach to functional safety throughout product engineering, development & manufacturing to minimize hazardous situations and the risk of accidents or other incidents.
Therefore, they implement elaborate functional safety activities to execute preventive action, and to ensure the availability, reliability, safety, and security of their products.
In safety-critical industries, safety requirements are laid out in standards or other guidance documents. For instance, the safety-related aspects of automotive systems development is governed by ISO 26262, which is a derivative of the general safety standard IEC 61508. Developers of medical technology have to adhere to the safety-related requirements of IEC 62304, ISO 14971, and other regulations, and the list goes on. Functional safety, however, is increasingly becoming a requirement even in the case of certain products that are not yet required by law to comply with these standards.
An ISO 26262 Functional Safety Lifecycle
Automotive development is a great example to showcase the anatomy of a sound functional safety lifecycle, as it’s a crucial topic in the industry and there are established and mature best practices to ensuring functional safety in automotive products.
An automotive functional safety lifecycle begins with hazard analysis and risk assessment. At this stage, the developer will analyze the faults, failures, and resulting hazardous situations that could pose harm to users of the end products. For each vehicle state, driving situation, and environmental condition, they will evaluate hazards based on their Severity, Exposure, and Controllability values. This helps prioritize hazards by assigning a Safety Integrity Level (ASIL) to them based on those three values. ASIL defines the necessary actions and measures to be taken during development and after the start of production.
Safety information will serve as input to requirements engineers who will embed safety aspects into the product’s design. They will specify Functional Safety Requirements that shall be traceable to the documented items verifying them. Functional Safety Requirements are broken down into Technical Safety Requirements, and it is made sure that they are addressed adequately during development.
After this comes the verification and validation stage. The difference between these is most easily explained by the following questions:
- Verification: Did we build the system right?
- Validation: Did we build the right system?
During this process, hardware and software components will be tested and integrated. This will be followed by the integration of these product components to form a complete system, which in turn will be integrated in the vehicle at the end of the process. The goal of this integration process is to ensure compliance with the specified safety requirements, and to verify that the overall system design actually covers all safety requirements. Verification, of course, is its own complex set of planning, specification, and execution processes, but this article will not attempt to cover all of these.
Throughout development, safety analyses are carried out to ensure all potential failures are identified and managed. Failure Mode and Effects Analysis (FMEA), Fault Tree Analysis (FTA), Dependent Failure Analysis (DFA), and the Markov model are all techniques used in product safety analysis processes.
Once development is done, various audits, assessments and confirmation reviews are carried out to ensure and document the correct execution of functional safety processes and their success. To learn more about these, as well as all the other processes of a functional safety lifecycle, join Intland's Functional Safety Summer Academy, and click below to watch the first session of this webinar series!