#safety analysis

How I used Medini in the FuSa project

Today I had a chance to introduce Medini tool for FuSa. During my presentation, I thought that it would be a good to post Medini in this blog.

Medini is a very good tool that guide safety engineers/managers to follow functional safety methodology that the tool supports.

When I execute FuSa process, I tried to set up a few principles for FuSa Execution based on FuSa standard. These are as follows;

It is a framework for developing systematic system modeling, safety analysis and safety mechanisms. If you search the data, you will find several papers. Interested in the overall content of this framework, detailed data were not available, so that the whole was not understood.

For a complete picture, see the data at https://www.through-life-engineering-services.org/downloads/campean.pdf.

If you…

Let’s think about the order of system FMEA and HW/SW FMEA

I got inspired from ECSS-Q-ST-30-02C, and I post it regarding this topic.

I’m not sure how many FMEAs are required, but let’s assume that there are 3 kinds of FMEAs; System FMEA, HW FMEA and SW FMEA.

In this case, which FMEA should be performed at first ?

My conclusion is that System FMEA should be performed at last, and HW and SW FMEA should be  performed at first.

The reason is that FMEA is…

Two styles of FMEA

SAE J1739 is a FMEA standard, whose title is “Potential Failure Mode and Effects Analysis in Design (Design FMEA), Potential Failure Mode and Effects Analysis in Manufacturing and Assembly Processes (Process FMEA)”

If you look a structure of a FMEA sheet, then there is a column “cause”.  and if you proceed to follow, there is a column “prevention”, “detection”, or “recommended action”.

Sample…

How Do I determine quickly that FTA is poor?

I have some criteria to determine that it is not mature within 10 sec.

1) There are no AND gate

No AND gate means that there is no safety mechanisms. It also means that it is not complete. if any fault occurs, it can trigger to Top level event. It is not mature FTA. There is no remedy how to handle.

If you have time, please check cut-set analysis result. Generally SPF(single point fault) is not…

Useful AUTOSAR specifications for functional safety

Recently I had a chance to review AUTOSAR specifications, and I share useful documents for functional safety.

Engineering aspect, safety analysis is key task for functional safety. I recommend that they are insightful.

They are recommended not only for safety engineers in automotive domain but also for safety engineers in other domain.

Explanation of Error Handling on Application Level

Overview…

A Function Failure Approach to Fault Tree Analysis for Automotive Systems

If you consider that SW FTA is mandatory, then try to review this paper.

Then you will have a method to generate systematically from functions.

Of course, it is not full automatic. Fine-tuning depends on engineer’s knowledge

Prerequisite: functional decomposition

What are benefits from safety analysis?

Safety analysis should be derived from design. I prefer that FMEA or FTA should be derived systematically.

And what if there are nothing identified additional safety requirements from safety analysis?

It would be good news, because your design is safe even though you considered diverse failure conditions.

But what if there is no history to improve your system safety and there is nothing…