Automotive functional safety ISO26262

Quite often, Safety Engineers are confused between Functional Safety requirements (FSR) and Technical safety requirements (TSR).  What level of details are to be provided in both the requirements and where exactly to cut the boundaries between these two is unclear. We will discuss the same in this post. Requirements Hierarchy Functional Safety Requirements (FSR) are derived from Item definition, HARA and Safety goals and are traced back to Safety Goals. Each Safety goal shall have a minimum of one FSR associated with it. Technical Safety Requirements (TSR) are mainly derived from FSRs. Each FSR shall have a minimum of one TSR associated with it. The below image provides a hierarchical view of requirements/activities flow from ISO26262 Part 3 – Item definition to Part 5 Hardware Safety Requirements (HSR) and Part 6 Software Safety Requirements. Also visit our YouTube video which explains the flow of Functional Safety requirements. Difference between FSR and TSR This table gives the...

This is a recording of our Functional Safety Systems Webinar that was conducted on 10-November-2021. Click on the image below to download the webinar slides

This is a recording of our Functional Safety Systems Webinar that was conducted on 10-November-2021.

In this blog, we present a simple yet comprehensive approach of how to write a high-quality Technical Safety Requirement (TSR) document, which considers all the Safety relevant aspects of the System and sets the right direction for the Software and Hardware teams. To begin with, it is important to understand what is the difference between an FSR and TSR. FSR (Functional Safety Requirements) describe the WHAT , i.e., WHAT must be done to achieve Safety Goals. TSR describes the HOW . i.e., How the Safety requirements should be achieved. It describes the technical realization of the Functional Safety Requirements of the project. TSR is the starting point for SW and HW Safety. For a specific item, there are 8 topics that TSR should cover. The topics are: 1. Intended Functionality 2. Fault Handling 3. Graceful degradation and Safe State 4. Freedom from Interference and Independence 5. HW Metrics 6. Special cases 7. Production and Service 8. Fault Injection Testing 1. Intended Functionalit...