I’m trying to get a new F450/Pixhawk quad flying. As soon as it takes off, the quad spins on its axis at a rate of roughly one revolution per second. Pushing the yaw stick in either direction doesn’t have any effect that I can notice. The PIDs are at default values, but even so, the quad shouldn’t be this unstable, right?
I’ve calibrated and re-calibrated everything, including the radio. I’m using the u-blox external GPS/compass on a mast. Radio is FrSky Taranis/Delta-8. I’ve tried the compass interference test which seems to be OK.
I’m attaching a log of my short test ‘flights’. In the first flight I applied no yaw. In some of the subsequent flights I tried applying full left/right yaw. I also very briefly tried switching to Alt Hold mode which didn’t seem to have any effect on the yaw. Pitch and roll just added to the instability which I guess would be expected.
Examining the log, the only strange thing I’ve noticed is that desyaw oscillates along with yaw. Shouldn’t desyaw remain constant, seeing as I have the yaw stick centered?
If anyone can spot any clues as to what might be going wrong I’d be very grateful.
Can you enable RCin and RCout logs and try again please?
des yaw is chasing yaw , so I think looks like its not a radio demand issue. If des yaw was leading then it would look like a radio command. des yaw will chase if the yaw can not be maintained, that’s how it is coded. I think it is so if anything outside causes an un-commanded yaw that copter doesn’t try to spring back and fight itself.
are you sure all motors and props are correct direction?
The yaw is not oscillating. That pattern is actually because the compass ends at 360°, and starts at 0° again. It’s just showing it spinning around. And Stu rightly points out, DesYaw gets dragged along by Yaw, anytime Yaw is ahead by 10 degrees.
I think the problem is that you have your motors spinning the wrong way.
Thanks very much for taking a look. I had suspected a gyro issue as I had experienced some gyro health messages. But I re-checked the motors one more time…
…well, I like to think the motors and props were going in the correct direction, just not in the right place on the frame! I’ve switched the CW and CCW motors and now the quad is flying stable. Beginner’s mistake. Thanks again.