I'm running a 2014 RTF 3DR Quad with 3.12 (yea, I've been told to upgrade).
I noticed yesterday that in stable hover on a windless day, my motor (RCOUT) outs are not the same. The logs clearly shows that motors 1 and 4 are sort of in sync while 2 always runs high and 3 low. See jpg below.
What's interesting is that I looked back on some original logs (no changes since then) and the 4 motors were very together in windless stable hovers. Then beginning (maybe after a crash?), they diverged.
I decided to try an experiment and placed the quad on a table and X/Y leveled the Pixhawk (using a bubble level). I powered it only using the USB, armed it and raised the throttle. I moved the quad around a bit to make sure everything was working and being logged okay.
I pulled the log and graphed RCOUT again:
Notice all motors were together as expected before I moved the quad. Also note I graphed the Gyros to see if the Pixhawk thought the quad was tilted and had to compensate. After I placed the quad back down note that the motors remain unaligned/synced with motor 2 clearly getting more input from Pixhawk which is obviously trying to compensate for something even though the gyros are still along with the accels.
Any idea what the Pixhawk is trying to accomplish here? In addition to discovering more about how to read the logs and figuring out how this whole thing works, I'm also looking to see if I might have an issue with 1 or 2 of my motors. i.e., being a little preemptive to fixing an issue before it dies in flight. :-)
Any ideas or answers greatly appreciated!
Tim
Replies
I wonder if the motor RCOUT differences are the result of some tuning that APM does as it observes stable flight? e.g., adds in known trims of some sort. In my case, I know my quad is weight biased to the rear a little (because that's where 3DR put the battery straps for some reason).