Help understanding something about the Kalman filter
Posted: Sat May 07, 2016 7:10 am
Hi guys,
I'm struggling right now, to understand why my copter sometime behaves incorrectly. It seems to go in 'divergence' and I have to switch immediately to manual mode to regain control over the copter.
At the very beginning I thought that that could be a problem with the GPS. Could be that sometime it gets some not valid information from satellites and get crazy. So I took a look at the log files and found something that I cannot really explain.
Look at the picture here:
In blue is the GPS height and marked in green is the estimation from the Kalman Filter (POSD) also the vertical position of the copter. They should match but it seems that during the progagation calculation the Kalman filter divergence a little bit and than converge after some time. The spikes on the picture are the calculated estimated of the altitude. It seems to me that the process noise of the system not really match what has been programmed in the code.
So I have few question for you experts
1) Are the spikes above a problem? Or could be the cause of the rapid loosing altitude of the copter?
2) Is there any possibility to change the process noise of the Kalman filter in the code, without recompiling it?
3) Do you experiment sometime the same thing?
I'm struggling right now, to understand why my copter sometime behaves incorrectly. It seems to go in 'divergence' and I have to switch immediately to manual mode to regain control over the copter.
At the very beginning I thought that that could be a problem with the GPS. Could be that sometime it gets some not valid information from satellites and get crazy. So I took a look at the log files and found something that I cannot really explain.
Look at the picture here:
In blue is the GPS height and marked in green is the estimation from the Kalman Filter (POSD) also the vertical position of the copter. They should match but it seems that during the progagation calculation the Kalman filter divergence a little bit and than converge after some time. The spikes on the picture are the calculated estimated of the altitude. It seems to me that the process noise of the system not really match what has been programmed in the code.
So I have few question for you experts
1) Are the spikes above a problem? Or could be the cause of the rapid loosing altitude of the copter?
2) Is there any possibility to change the process noise of the Kalman filter in the code, without recompiling it?
3) Do you experiment sometime the same thing?