- Joined
- May 27, 2014
- Messages
- 105
- Reaction score
- 9
While flying today I noticed a horrible horizon change in the matter of seconds. Anyone know of a fix?
This is normal behavior for a small cheap IMU if you're flying in a long curve.
....
You cannot calibrate away this drift, but you can make it smaller with an IMU calibration at different temperatures.
They map how the gyros drift at different temperatures at steady state and then use this info to cancel out that error during flight to make the drift smaller.
.....
Cheers
Hakan
Very helpful analysis but also a bit disconcerting. Does that mean I should not expect any real improvement even though the camera module has been replaced? This issue does not appear to afflict everyone. I also own a P2 with the Zenmuse H3-3D gimbal and it remains level quite well. Does this mean they used better gyros on that gimbal? I guess I'll just have to hope I see some improvement when I get to fly. Installing the P3P 1.05.003 firmware now.This is normal behavior for a small cheap IMU if you're flying in a long curve.
IMU:
It has three gyros that requires constant adjustment against the accelerometers and heading sensor since they drift quite fast, 1° /sec maybe?
When the quad is making a turn they will stop updating the gyros with data from the accelerometers and rely on gyros alone, which means that things will start to drift.
During a long turn they have two choices, either continue to just use the gyros and let them drift or start using the accelerometers again, but when you fly in a curve the centrifugal acceleration will make the accelerometers point in the wrong direction which means that the gyros will be adjusted the wrong way.
The result of this will be a horizon that isn't level!
They use a Kalman filter to fuse data together from gyros, accelerometers compass but you can't solve this problem without good gyros, and they cost a lot!
A side effect of this is also that the compass will show the wrong heading since the IMU has the wrong idea of the horizon.
You cannot calibrate away this drift, but you can make it smaller with an IMU calibration at different temperatures.
They map how the gyros drift at different temperatures at steady state and then use this info to cancel out that error during flight to make the drift smaller.
You can minimize this problem by changing the way you fly the quad and have a good calibration.
Cheers
Hakan
This is normal behavior for a small cheap IMU if you're flying in a long curve.
IMU:
It has three gyros that requires constant adjustment against the accelerometers and heading sensor since they drift quite fast, 1° /sec maybe?
When the quad is making a turn they will stop updating the gyros with data from the accelerometers and rely on gyros alone, which means that things will start to drift.
During a long turn they have two choices, either continue to just use the gyros and let them drift or start using the accelerometers again, but when you fly in a curve the centrifugal acceleration will make the accelerometers point in the wrong direction which means that the gyros will be adjusted the wrong way.
The result of this will be a horizon that isn't level!
They use a Kalman filter to fuse data together from gyros, accelerometers compass but you can't solve this problem without good gyros, and they cost a lot!
A side effect of this is also that the compass will show the wrong heading since the IMU has the wrong idea of the horizon.
You cannot calibrate away this drift, but you can make it smaller with an IMU calibration at different temperatures.
They map how the gyros drift at different temperatures at steady state and then use this info to cancel out that error during flight to make the drift smaller.
You can minimize this problem by changing the way you fly the quad and have a good calibration.
Cheers
Hakan