Stable hover but wobbles and falls on large inputs

At this point in time I want to avoid having to buy any new parts. The only reason I revived this project again now was because of the current lockdown and apart from that I don’t get to spend much time flying RC stuff lately. I replaced my old APM1 controller back in July 2018 with a Pixhawk and only got as far as doing one or two test flights and that’s where I left it.

Hi guys,

Please see below my latest BIN file:

I managed to get one flight in before the battery alarm went off and the wind started to pick up. No wobbles and falls this time so it looks like we’re making progress :slight_smile:

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I managed to get a few more flights in today and even did some alt_hold tests. It holds altitude way better than what I’m able to do manually but the motors do pulsate occasionally for a few seconds.

I lowered the Throttle Accel values down from 0.125 to 0.1 but it still does it. The Pixhawk itself is enclosed so I don’t believe it to be air flowing over the baro or sunlight hitting it.

That’s looking pretty good. A bit of final tuning and you should be there. Out of curiosity why are you using Save Trim?

I had a little bit of a drift and I found the SaveTrim method easy and quicker to do repeatedly compared to the AutoTrim (at least based upon the instructions I read). I initially had AutoTune programmed on ch7 and I was afraid that I might enable it by accident so I replaced it with something else that could do less harm for now. :laughing:

Do you have any other recommendations perhaps? If the weather is nice tomorrow I want to see how it goes with Loiter and once I’m comfortable with that then I’ll move onto AutoTune perhaps.

I think its a a waste of time and battery to trim to a condition that changes all the time with either Auto Trim or Save Trim. Center the Tx trim sliders on the Transmitter, perform a proper accelerometer calibration and that’s it. Use the sticks for wind drift in Stabilize and AltHold.

What I’ve found is it’s important to get the level horizon done very accurately, and get all the motor mounts (and props) perfectly straight and level.
Don’t assume the surface you are on is level, and don’t level just the flight controller - level the whole frame from motor to motor using a light weight spirit level (easily made) and wedges or something under the landing gear to lift up the low sides before hitting the “Level” button in Mission Planner.
If you get all that right you can even find AltHold and Stabilise wont be affected much by a bit of wind.

I wasn’t planning on redoing the trim for each flight though. I did the level calibration on two different surfaces but it was still a bit off so that’s why I used SaveTrim. Now that its done any other drifting will be corrected with stick inputs yes.