Quote:
Originally Posted by Dale
One of the biggest problems to overcome with this kind of system is gyro drift. The more turns and bumps a robot encounters the more the gyro and the code tends to drift in its understanding of where "North" (not magnetic north, just a consistent orientation) is. Noise on the analog line will also add to this...there's always noise.
When we tried doing this a few years back, with the old IFI system, we could only get good results for the first 20 seconds or so before the errors accumulated so badly as to cause the system to need recalibration. Have you noticed that to be a problem with the cRIO and it's better A/Ds? Is there a way for the driver to reset the definition of "North" if the gyros loose their way?
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The combination of the 12-bit ADC on the cRIO (versus 10-bit on the older IFI system) and the faster polling rate make gyros much less susceptible to noise.
Quote:
Originally Posted by PVCMike
From what I understand through testing Brendan and Brian also discovered that through out the 2 minutes and especially going over the bump the robot would lose its calibration. To solve this they have used some additional sensors (other than the gyro) to automatically re-calibrate the gyro every so often on its own. They have also programmed in a button on the joystick so you can position the robot and click the button to recalibrate which seems to work well too. Feel free to come by our pit at GSR (Team 1058 the PVC Pirates) and ask for Brian or Brendan and they'll be able to tell you all about it!
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What the degree/second rating of your gyro chip? If it's already a 300 deg/sec, you could measure the drift over time. Sometimes the noise is biased in one direction, and you can offset this just by adding/subtracting a coefficient at your software at regular intervals.