Compass variace & in-flight yaw alignment

(S) #1


I just finished building my hexa with the cube 2.1 and the here 2 GPS (running UAVCAN).
However I have some issues:

  1. I get loads of “compass invariance” errors. I did the compass calibration more than 10 times now but still it seems to be funky. Also the orientation of both the external compass and the internal cube 2.1 compass are the same: both point exactly to the front of the craft.
  2. The copter does not track well. When I just pitch forward the copter tends to fly to the right and also looses some height. (I do not mind this issue cause I can fly racequads too. however it defenitly should not be like that. something is wrong here and I do not want to risk loosing my gear.)
  3. Is the in-flight yaw alignment somehow connected with the problem I get from number 2? can this be the reason that the copter does not track well?

I also recorded some videos with a little bit of information:
Flight one:

Flight two:

Overview of the craft:

Log flight 1 (4,2mb is too big for the direct upload thus the dropbox link):

Log flight 2:
filght2.BIN (944.7 KB)
(AMV) #2


Did you set your PIDs? ESC calibration? Motor Calibration? remote calibration?


(S) #3

yes PID’s are auto tuned, ESC’s, motors and remote is calibrated as well.

(AMV) #4

In general, you dont stay with the autotune PID, you use them like a start point to give a final tune. As you say in the first video, the takoff vibrations its a sign of “PID Autotune”, very common on the autotune on big copter i think, could be a miss of D on the pitch or roll if the shake dissapear after takeoff

Did you do the CompassMotor calibration?


(S) #5

No i did not do the compass mot calibration yet. I‘m gonna test it this week.
are there any other options you can think of? it seems weird to me that the copter does actually fly not too bad while still getting these errors. I mean I assume the errors only appear when I use a lot of yaw input and thus changing the heading of the copter. am I right?
would you recommend only using one compass? so only the internal or only the external? is there any other way I can check if both of the compasses are actually alright or if their somehow damaged?

(Tan Pham) #6

I have same problem with my hexacopter. did you fix it?