I'm pretty new to quadcopters and APM and have been mostly learning as I go. So far I have my quad flying decently in stabilize mode and altitude hold but I am still working on loiter, then RTH. I think I have narrowed down my issues with loiter not working but wanted to check with somebody who knows more about it than me. I briefly had a good loiter the other night (quad stayed within a 5m x 5m x 5m box for about 10 seconds.. the only time loiter has really done what it's supposed to) but haven't been able to replicate it.
I'm pretty sure it has to do with my compass but I am still trying to work that out. I get about 33% interference in compassmot, I have my APM 2.5 board mounted on the top level as far away from battery/ESC as possible (about 3 inches from both). When trying to loiter, is it correct in assume it basically makes an instant waypoint for it's current location and then basically tries to be inside that waypoint? So if I look at the NTUN data for while it is loitering, the WPBrg should be the bearing to the loiter waypoint? Or is this parameter continually refreshing to point to home as the waypoint bearing? Also, can anyone confirm the unit of measurement is in radians?
Lastly I noticed something with my motor output, it looks like motor 4 is consistently lower than the other three motors. Is this bad? In flight it is pretty stable and no notable pitch/roll in the direction of motor 4. I was just curious why it seems to be under performing compared to the others.
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Just in case anyone google's this post with a similar problem, it was complete lack of attention to detail on my part. Turns out motor 1-3 are all the same, 770kv motors. Replaced motor 4 after a crash and put on the wrong motor, an 880kv motor. They look identical.