Quote:
Originally Posted by Luiz12
So from what I understand is that I have to have a set point, which I assume would be zero since when the angle reaches zero
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Yes, but it's a bit more complicated than that. Keep in mind that the gyro measures yaw (change in angle) around an axis through the gyro itself, but your robot does not balance around this axis; it balances on the bridge. You may have issues because the yaw rate is not directly proportional to the bridge angle.
Quote:
Originally Posted by Luiz12
basically from what I've read the only thing that I would need to tune would be the proportional gain.
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As mentioned earlier, mechanical systems have momentum; for this reason, a proportional gain will almost always result in oscillation around the setpoint. Because of the double hinge setup for the bridge, however, it has a noticeable resistance to tipping, so an incredibly small P may allow you to successfully balance without tuning I or D, but your robot will be moving very slowly to the setpoint, which could possibly, depending on your wheels/drivetrain, be ineffective due to stalling or slipping. For a time-effective balancing mechanism, you will likely want to tune both P and I.
Searching the forums will yield a wealth of discussion on how to tune a PID loop; there are also a number of discussions about how to tune PI loops and ignore the D.