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I am simulating a NAO robot that has published physical properties for its links and joints (such as dimensions, link mass, center of mass, mass moment of inertia about that COM, etc). The upper torso will be static, and I would like to get the lumped physical properties for the static upper torso. I have the math lined out (inertia tensors with rotation and parallel axis theorem), but I am wondering what the best method is to structure the data.

Currently, I am just defining everything as rules, a method I got from looking at data Import[]'d from struct's in a MAT file. I refer to attributes / properties with strings so that I don't have to worry about symbols being defined. Additionally, it makes it easier to generate the names for the different degrees of freedom.

Here is an example of how I am defining this: http://pastebin.com/VNBwAVbX

I am also considering using some OOP package for Mathematica, but I am unsure of how to easily define it.

Brian Tompsett - 汤莱恩
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eacousineau
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  • I just realized that I could find an OOP package and then use something like MathOO and define it all using constructors... I will be trying this out too. – eacousineau Jul 10 '11 at 22:01
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    Although the couple of OOP packages for Mma are interesting, I don't think that they really work performance-wise... I think that just using `DownValues` is easiest - it's what Mma is optimized for. Daniel Lichtblau and others have given talks about [data structures in Mma](http://library.wolfram.com/infocenter/Conferences/321/). – Simon Jul 11 '11 at 08:14

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For this task, I had taken a look at Lichtblau's slides but could not figure out a simple way to apply it towards defining my data structure. I ended up using MathOO which got the job accomplished since efficiency was not too much of a concern and it was more or less of a one-time deal.

eacousineau
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