[tech360]

I'm (finally) back to working on my quad again after being away from it for about 6 months. I've upgraded to 16.09 and have rock-solid flights using Basic, Complementary+Mag, and Complementary+Mag+GPSOutdoor for the Attitude Estimation algorithms.

I wanted to try the Autotune function and so I read the documents carefully, configured my flight modes and tried it out. Well... the quad takes off (climbs) very quickly once the testing begins and I have to cut back to FM 1 to bring it home. It's not a gentle climb, it gets up to 70' or 80' in just a few seconds.

I read the Autotune docs and know about the 50% throttle rule for hover, but I'm not sure what to do here. Do I add weight to the quad? Do I swap out props to reduce lift? What does everyone else do to prevent fly-aways during AT?

Thanks in advance for any tips you can give me!

[f5soh]

Vehicle has tendency to climb during Autotune procedure, you just need to reduce the Throttle to reduce / stabilize the climbing.
If you add weight or change props, the Autotune results (PID) are not the same and not valid anymore for the normal vehicle's configuration.

If you use autonomous modes like velocityroam or GpsAssist i do not recommend Complementary+Mag+GPSOutdoor, please use INS13 instead.

[tech360]

Thanks for the info. I *think* I tried reducing throttle but it caught me off guard and I might have panicked and switched back to FM 1 too soon.

I can see what you mean about PIDs being off if I change the vehicle characteristics. I'll wait for the next good day and try it again, this time being a little more prepared for the behaviour.

As for the modes, I've been gradually working up to INS13. I wanted to be sure that the quad was stable in the other modes first and that GPS reception was good. I've tried it a few times but I seem to get some wandering and instability (hence why I was trying out Autotune). The HUD shows a constant tilt to the right even after calibration so I'm guessing that I have to play around with the "Rotate Virtual attitude relative to board" or "Auxiliary Magnetometer Orientation".

[f5soh]

You should hover and stabilize the altitude first, switch to Autotune and reduce the Throttle.

You have direct control to the Thrust using Throttle stick so you can control the altitude.
Nothing related to the 50% throttle for hover.

[TheOtherCliff]

The reason this happens is that your ESCs don't have "light damping (BLHeli)" or "COMP_PWM (SimonK)"

Without this, the ESC will use power to make the prop spin faster, but will only use air drag to make it slow down.  AutoTune makes the props spin faster and slower many times.  Props get faster very quickly but it takes a longer time for the props to slow down, so on the average the props will be spinning faster when they should average out to be "no change in throttle".

[tech360]

TheOtherCliff, that makes perfect sense, thanks for the info.

I've not programmed my ESCs (SimonK 30A), they're running with stock settings. Perhaps I should learn how to do that...