Bob Anderson wrote:Once this is done, the two modules make excellent, stable gyros.
sebmadgwick wrote:Thanks for this info, this is of interest to a discussion we are having at: http://forum.sparkfun.com/viewtopic.php?p=86916#86916
My results (HP filter attached) suggest that gyroscope bias drift is shifted to a steady-state during motion (see plots in above link) by as much as 0.3rad/s in <1s. Point being that as a stead-state error, it is not solely the effect of the HP as you have described. Any input you may have on the discussion would be appreciated.
Can you provide some extra info on...Bob Anderson wrote:Once this is done, the two modules make excellent, stable gyros.
What I would like to know is:
- Do you have any software filtering or do you simply remove a constant pre-calculated bias-off-set?
I'm not using a software filter (Kalman or other). I determine a bias value by averaging readings taken over 1 second using a 12 bit A/D. I keep an extra bit, so the bias value is known to 13 bit resolution. Sitting on by bench, this bias value essentially does not drift. I can come back day after day and meaure the bias and get a result reproducible to with one bit. There is a small tempeature dependance -- if I put my finger on the device, the bias will change a few counts.
- The gyroscope bias must drift by some amount; can you quantify this in anyway? e.g. 1deg/s over 2mins
Bob Anderson wrote:....I integrate (output - bias)*calib to get degrees of rotation. Because there is noise in the output, the above value will "walk" (random walk). .....
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