[chuck-users] Bluetooth and Wiimote: a long-term feature request

Kassen signal.automatique at gmail.com
Mon Apr 21 12:24:02 EDT 2008


On 21/04/2008, Luigi Rensinghoff <luigi.rensinghoff at freenet.de> wrote:
>
>
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> nope..sorry....
>


Hmmm, I couldn't quickly find a good one either.

The trick is that if we have some signal representing a "position" then the
first derivative will be "movement". If we sense the gravity acting on the
Wiimote as it's "position" (orientation, in this case) then any changes in
that will represent the forces acting on the Wiimote. For one thing; it's
clear the thing won't move unless some force is acting on it, right?

Ok, I'm not the greatest digital filter wizzard but if we have this signal
and pull it through a SVF we know for sure that the DC component of the
signal and other very low ones (representing the orientation of the object
at rest) will end up on the LP output. Once the orientation starts changing,
assuming the change is in the range of the filter's frequency, this will
make the change in the value appear in some way on the other outputs.

Where it gets hazy for me too is how that results in the derivative and
that's where I hope somebody like Perry will help us but that's the rough
outline of how I understand it works. Admittedly a vague outline in
dimly-lit smoke but filters are hard stuff (at least for me). Maybe I can
re-find that printout I had.


Apologies to the real filter wizards around here that are no doubt gnashing
their teeth in frustration at this crude explanation :¬).


Kas.
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