SafeML Part-1 – Introducing “SafeML” for Safety-Critical Systems Development

Safety Information Management is a complex and difficult task.

Developing a safety-critical system requires managing large quantities of information describing the system’s hazards, risks and safety features. Manual approach currently used is a huge effort managing and tracing risks and safety requirements. Geoffrey Biggs from AIST proposes to apply a modeling technique to help this task by using “SafeML” – safety modeling language.

Geoffrey Biggs

Robot innovation researcher at AIST, Japan.
His research straddles the related areas of software development tools, processes, and architectures, and development of safety-critical systems (specifically, service robots).  See his profile, research, publications and more

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(Transcript the video Part-1 – 4min 14sec)

Hello everyone, I am Geoffrey Biggs from AIST(National Institute of Advanced Industrial Science and Technology). Today I am going to be talking to you about how you can use “SafeML” to improve traceability of your safety information. So I’m going to start with Part1 which explains the goals of what I am going to be talking about today and background about the work we’re doing.

  Current problems in managing safety information

The problem we’re dealing with is that safety information is extremely difficult to manage during the development of a safety-critical systems project.

This is due to various factors including the complexity of the information. It’s duplicative and in various different places, different formats and with different people.
Also there are communication problems between these people who are managing information.
For example, this information can be communicated during meetings or in text reports which is very time consuming and ambiguous.

And finally these factors mean that there is a large cost in terms of time and money to develop and maintain this information this means that overall safety information management is a very complex and difficult task.

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  Flow of safety information

Here’s an overview of the flow of safety information during the development of a safety-critical system.

In the middle, we have a system engineer. He is developing a system and going to be responsible for designing it, producing the requirements and so on.

Based on their requirements he produces, safety expert is going to produce safety analysis which is going to produce a list of the hazards and risks and so on involved to using this system.

And this is going to be combined into a system model which will hopefully take into account these hazards and risks, to the safety features and therefore make the system safe. Based on this, we need to produce report presentable to the certification agency. And this agency then tells us that the system is going to be guaranteed to be safe or not, and we can get the certification and begin starting that system.

So there are problems here where we’ve proven through real world experience that these manual text and voice based exchanges of information are very ambiguous and lead to errors on the safety information.

And furthermore, when any of this information changes, because it is stored in many places as you see here on the slide, it is very hard for us to update it in all of the places and maintain the consistency of the information. This makes judging the impact of the change in the system, such as a new hazard being identified or new safety features been added, it’s very time and resource intensive to get correct.

So our approach to solving this is to apply model-based methods.

In this case, we do use model-based methods to manage the safety information. So what we are doing is that we are adding the safety information that we produced into the system model and recording it there.
To achieve this, we’ve created a modeling language that we call “SafeML” for Safety Modeling Language.

  What is “SafeML”?

SafeML is a tool for communication of safety information amongst members of a development team and among agencies involved in safety certification.

It’s based on SysML, which means it can be integrated completely with system model.
And SafeML is based on both international standards for safety critical system development and on formal safety analysis methods.
So as you see on the slide here, you can see where SafeML is useful.

We have a model-based system done in SysML. And we have SafeML being used to model all our hazards and risks and so on that are produced from safety analysis.
So this is then integrated together into a single system model using SysML and SafeML which produces a system model including the safety information.

  Benefits of using “SafeML”

This has several benefits.

Benefit – 1 : Stores safety information in one place

First of all, the safety information is only stored in one place. This means  when anything needs to be updated, we only need to update it in one place.

Benefit – 2 : Being able to take an advantage of automated computer assistance

And because it’s a model-based, the computer can automatically update any other products produced from the model such as reports. You also gain the benefits of automated computer assistance because now we make computer understand the format of our information, we can use the computer to perform analyses. For example, we can perform an impact analysis to determine what parts of our system are impacted by change in the known hazards.

Or we can use it to generate the very large reports that are need to be delivered to the certification agencies reducing the time and manual work required when managing safety information.
We can even change how we display this information. When you have textual reports and tabular reports of safety information, it is very hard to change how that is formatted to suit to how you are using it.
So instead, with SafeML we can automatically change how the computer displays the information such as tabular views, matrix views and model views to suit to what we are doing with the information.

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