Hi all,
I recently got my quad all set up (DIYdrones electronics, home made frame) and I've had a couple of very short, sometimes sucessful, flights.
One thin that's bothering me is there seems to be some yaw drift when in stable mode. When I apply throttle for takeoff one pair of motors will continue to accelerate and the other pair decelerate until they stop. If I apply more throttle however I still seem to be able to fly.
I've watched this happen in configurator. The right and left motor commands increase while the front and rear decrease. The yaw curve on the PID chart continuously increases. I've attached a screenshot of this.
In Acrobatic mode this doesn't happen. All the motor commands remain the same and all the PID curve stay at 0 (when stationary).
I've noticed that the Artificial Horizon reports a 0.1 - 0.2 degree/sec drift to the left. Why then is stable mode trying to compensate for this while acrobatic mode does not?
My magenetometer is off being repaired at the moment. Is it likely that this will resolve the issue?
Thanks for any suggestions,
Chris
Replies
Thanks for all the replies, they make sense. Like I said, it doesn't seem to effect flying. I thought I'd try and be clever and mount the quad in a rig to try and tune the pitch and roll PID values. However, because it's fixed in place it can't correct its yaw and two motors go to full while the other two go to nothing. Makes it impossible to do any tuning.
Perhaps if I set all the PID values for yaw to 0 it wouldn't try to correct its heading? Just for while it's in the rig of course.
Cheers,
Chris
your yaw is not drifting
disarm the motors and re-arm them, look at this char again, it should be a straight line
the point why it decreses it's command is, that it tries to get into a certain position, if it doesn't get there, it tries harder (like a human would do)
Chris,
the magnetometer should fix the yaw drift issue.
I suspect that the left+right engines increasing / front+back decreasing is because it's trying to do heading hold. Basically it's because that drift is building up between when you turn on the APM and when you finally take off. So as it takes off it's trying to correct for the built up yaw error all at once. I think a couple things to try would be:
- make sure your radio is centered and you've done the rx calibration in the configurator or CLI
- don't move the yaw stick at all between when you power up the APM and when you start flyign
- DO waggle the yaw stick just before taking off <-- i don't think this will help .. i think it will make it worse but maybe give it a try anyway..perhaps I've read the code incorrectly.
Sorry, I never use Acro mode (too dangerous!) so I can't help you as to why they act differently.
-Randy