SysML: From idea to simulation in 30 minutes

Experts in modeling understand that a SysML model is much more than its representation in the form of a diagram. With a little experience, we can quickly create impressive models that demonstrate this. For example, we can bring a model to life through simulation. I will show you how this can be realized with Dassault Cameo and where the pitfalls lie in a 30-minute video of "MBSE Execution".

A flashing light simulation in SysML

MBSE-Execution is a channel on YouTubewhere there are a number of other videos. This channel is an insider tip for modelers and it's worth browsing through the list of videos. Some of the videos are "unlisted", so they won't show up in a normal YouTube search!

First, here is the actual video, which shows the path from an empty model to an executable simulation with SysML in half an hour. If you don't want to watch the whole video, here are a few highlights:

• The actual modeling begins with 1:15.
• With 3:14 the block definition diagram (bdd) is ready and modeling of the internal block diagram (ibd) begins.
• The modeling of behavior begins with 3:58.
• Be careful, after the modeler has finished modeling the behavior (13:28), he arranges the state machines in the ibd. At first glance, this is a nice picture, which is also important: after all, it is also about good communication. However, this is a clean model whose advantages are not immediately apparent from the diagram.
• With 13:28 the simulation of the flashing light also begins.
• In the rest of the video, from 20:10it's just a matter of configuring the simulation. Depending on how realistic you want it to look, more or less effort is required. For example, the modeler looks for suitable images for the animation of the lamp.

It's easy, isn't it...?

When an expert performs an activity, everything always seems so incredibly easy. But the easier it looks - acrobatics, juggling, magic tricks or modeling - the more difficult it actually is. It takes years to model as shown in the video.

Nevertheless, it is comparatively easy to follow the video and understand what is happening. And that's why it's so important to differentiate clearly between authors and readers of the model when modeling. Not every stakeholder needs to be able to model, but all stakeholders should be able to understand (read) models.

Only a few stakeholders need to be good at modeling. But all stakeholders should Being able to read models!

The question of "why"

The title of the video already answers the question of "why": It is about creating a SysML model that is to be used for a simulation. But this is only one of at least 18 things we can do with a model. But a model is an abstraction for a purpose. Therefore, when modeling, we should be clear in advance what this purpose is.

Without a clear purpose, modeling can quickly become an end in itself. Here it is worth thinking about one of the most important purposes of a model: Communication. Incidentally, communication corresponds to the first stage of the SYSMOD Maturity Models. If not even this level is reached, the models usually fall into one of the following two categories:

The dangers of aimless modeling: spaghetti models and ivory tower models

Spaghetti models are similar to what we call in programming Spaghetti code denote. It is a model where conventions are missing, language features are used inconsistently, and so on. As a result, nobody understands the model, not even the author.

Ivory tower models: Unlike the spaghetti model, the author understands this model - but nobody else does! An ivory tower model is usually well thought out and could even be useful. However, it can usually do far too much, which makes it incomprehensible to all mere mortals. Even if such a model has value, it stands and falls with the author. A wonderful way to make yourself indispensable as an employee. But it misses the point of modeling.

Conclusion

The MBSE Execution Channel is an inspiration to invest in modeling. The video shows impressively how quickly results can be achieved with modeling.

However, it is important not to be fooled by the ease of the video. A bit of preparatory work, planning and training are necessary to ensure that there is added value for the team. But if this is taken into account and common sense is used, a lot can be achieved with SysML modeling.

Image source: Youtube video