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Unread 02-02-2009, 11:23
EricVanWyk EricVanWyk is offline
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Re: Noisy Accelerometer

Quote:
Originally Posted by mjcoss View Post
We're seeing the same kind of jitter in the accelerometer from this years KoP. In all directions (x, y and z) we are getting odd values for an at rest bot. The nominal values are suppose to be 1.5V at rest. X is 1.84, Y is 1.76, Z is 1.74.

I tried resting the accelerometer on the ground, away from the bot and no change. I swapped the accelerometer with one from 2005, and while there's a little jitter it's in the +/- .002 range.

Now the new on is more sensitive (300 mV/G) and it's possible that we need to replace the bandwidth filter on the board, and isolate the board better but I'm leaning more toward that the board is broke.
Your post is very informative, and a refreshing break from "It don't work". Thank You.

At rest, you shouldn't be able to see those values if everything is working - it corresponds to about 2.5g acceleration towards a corner. Something is wonky.

Do you have an oscilloscope? It could make debugging easier.

Can you plot the values over time? You may be able to see noise.

I would hold the accelerometer in each of the 6 basic positions (Z up, Z down, Y up, Y down, X up, X down) and record the values given. This may give you better insight into what is wrong.