Is your system architecture “Lego Legal”?

Sometimes, when you wander the web, you come across a story that makes you think about your job in a new way. This one, about “legal Lego builds” did just that.

Lambrecht describes “the model that forever changed LEGO,” an Audi TT that was difficult to put together, required the user to deform components for them to fit, and came with no instructions.

The article (or more accurately the linked PDF) is interesting for three reasons.

  1. Change came after failure: Lego’s are a famous brand and, having been around for 80+ years you would assume the have their bricks together(1). However, entering the brave new world of “build sets” the found that they needed to adopt standard building rules
  2. Unit test to find system problems: Some integration issues can only be detected in the full system, however upfront consideration of interfaces and tolerances can prevent large scale issues.
  3. Legal but on the boarder: The PDF shows legal / illegal and “boarder” cases. Sometimes the “boarder” is the only solution to the problem; but when you find yourself in a “it’s the only way” case, spend some time to figure out if that is really the only way.
Image result for legos
A large scale Lego build (2)

Small rules

With Model-Based Design what are the “small rules” that I would recommend following?

  1. Adopt a style guide: For MATLAB and Simulink Models consider the use of the M.A.A.B. Style Guidelines.
  2. Speed counts: A slow small function slows down your system. Each additional system slow system (or repeated instances of the same system) add up to a slow integration.
  3. Self contained: Models should be able to execute on their own, e.g. not requiring external infrastructure to execute. This is the distinction between a functional and an integration model.
  4. Swiss army knife: When I’m out hiking a Swiss army knife is a reasonable lightweight tool to bring to handle unexpected issues. Models should serve a purpose, not 100, that is why we have systems.
The 16999 Swiss Army Knife (3)


  1. No apologies for the bad play on words.
  2. Google image search can return things you would never expect
  3. Yes this is a real

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One thought on “Is your system architecture “Lego Legal”?

  1. I know I shouldn’t think like that, but I’m still fill wondered when I see people talking / advising / or arguing about modeling before coding and doing unit testing like a good thing. It could be obvious, but the majority of people ignore that. Conglatulation, I’m looking foward to seeying more articles like that.

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