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Unread 26-01-2008, 18:09
eugenebrooks eugenebrooks is offline
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Re: Gyro inconsistencies...

Chris has it right here. The dead band is the source of the symmetry problem. We sample our gyro at 152 hz and compute the integral using the trapezoid rule in 256ths. We use the average of many 128 sample sums, hard coded in, for the bias. The result is a drift of only a tenth of a degree or two for the 15 second autonomous period, with good symmetry.

Eugene


Quote:
Originally Posted by Chris Hibner View Post
I will almost guarantee that the problem is caused by asymmetry in the ADC and being augmented by the dead band.

In general, any dead band on an integrator is not a good idea if you want accuracy in your results. See this whitepaper: http://www.chiefdelphi.com/media/papers/1449

It's been our experience that with a good bias routine you can expect less than 1/2 degree of heading drift over 15 seconds worth of autonomous operation. Just be sure to have a lot of resolution in your bias calculation.

Last edited by eugenebrooks : 26-01-2008 at 22:49.