Is there a parameter that hard codes in a constant pitch offset?
I got the board installed to what I thought was level and find out that my plane actually flies straight and level when the nose is slightly pointed down.
So this results in the plane wanting to climb when I got to stabilize mode because what the board thinks is level is actually a climb attitude for the plane.
The short term solution I have come up with is to raise the tail of the plane when I first power on so that the sensors initialize with a slight pitch down. It's very hard to re-create the exact same down pitch between flights.
Is there a parameter already in the config that will fix this?
Or do I have to just tweak the code?
Other ideas?
Replies
I had pretty much the same issue today. It was the first time flying with my new APM in stabilization mode and I found that I kept having to use quite a bit of elevator and trimmed my elevator control almost all the way down to keep a level attitude. So I just extended my pushrod one turn to compensate. I expect that the next time I fly I'll be able to push my elevator trim up to almost level on my transmitter. We'll see how it goes. Stabilization worked great, though! I was very happy with it. Nice smooth landings.
A simple tweak to the code will cause issues as there is coupling between the pitch, roll, and yaw axes. That is why it is not a standard feature, as it has to be done at a low level by rotating the accelerometer and gyro vectors (to do it properly), and no-one has felt it is a big enough priority to deal with.
For small angles, you could get away with a simple tweak in the code, but it will introduce some errors into the attitude solution. The easy solution (and recommended) is to just hold the plane in the proper flying attitude during IMU calibration.