All posts for the month August, 2013

Oh! So the whole point of that little lecture on DC motor control was to point out this:


This sexy AutoDesk Inventor 3D simulation has motors bolted via the static face to the chassis, with a minimum of distance between the support and the wheel. Because that’s optimal, and because that’s normal for brushed motors. The motors have only just arrived, the simulation only has 4 parts *and it is already wrong* because it makes assumptions.

Which is not a big deal. But it’s a warning. “It worked in CAD” is an insidious trap for young players – the question is, when it fails to work in real life, do you change the part to match the drawing, or the drawing to match the part?

A non robots post! My friend Nathan, who is possibly more addicted to coffee than I am, and certainly more of a connoisseur, recently had a terrible experience – the handle on his coffee machine broke!

It is, I gather, a La Pavoni style lever machine, and this is the bit that broke:

2013-08-11 19.50.12_mid



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I think I now have all the parts for the tiny project I’ve had in mind.

It starts with the omniwheels:



These are smaller than I expected, but that’s fine, everything else is going to be small too. Omniwheels are slightly less useful than Mecanum wheels , because you can’t create the kind of sideways movement you can with Mecanum wheels, but that leads to some drive theory a little outside the standard “4 wheels and a gripper” paradigm.

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