For those of you who have read the comments in my other thread: http://www.diydrones.com/forum/topics/yadiya-yet-another-diy , I'm considering using two dual axis gyroscopes from ST Micro. I need a gyro for each of the axis: Roll, Yaw, and Pitch. So, they have combined Pitch+Yaw and Pitch+Roll gyros, and a single Yaw gyro chip. I could just get the Roll+Pitch and the single Yaw gyro and call it a day. However, I noticed that the prices for the dual and single axis chips are comparable, so I thought why not use the Pitch+Yaw, and the Pitch+Roll - so as to have 2 readings for pitch?

Heck, why not go all out and have differential measurements for each axis? I could get two Pitch+Roll gyros, and two Yaw gyros. Mount two of them on the top of the board, and two of them upside down and rotated 180deg on the bottom of the board - and I would get differential measurements for each axis - similar to the uber expensive ADXRS300 gyros - which are $50+ each. A set of 3 of those would cost $150+ and it would not be a flat board. I can get differential measurements for each axis using 4 ST Micro gyro chips for 8.7*4 = $35 , and the board would be flat! Even if I need a separate ADC to handle it, decent 8/10 channel adc's are for $10 or so.

Any comments on this approach? Are vibration problems serious enough an AHRS to warrant such measures? Will it work (better)? Is it worth chewing up an extra 3 ADC inputs?

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Hello,
the problems with the ST-MEMS gyros is the low resonator frequency oft 4 kHz. Iit is just the frequency of the vibration generated by the propellers. So ST sensors have problems with vibrations. The ADXRS work over 20kHz and do not have this problem. Also the piezo gyros from tolkin work above 20kHz.

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