[Solved] Bad altitude hold with 3.4-rc5

ArduCopter Copter 3.4
1

Hi, I have strange altutide hold behavior with 3.4-rc5. (genuine pixracer, ZMR250, 4S, 2204 motors, 5045 props, ~20% hover throttle).

With sticks at 50%, the copter moves up/down by 2-3 meters.

(i have other issues, like compass not calibrated after restart; ekf anomalies; but those are already reported on other topics.)

Here are my logs and the full param list:
https://drive.google.com/drive/folders/0Bzz1m9D3igS9YXdHTFBfT2R4aUU?usp=sharing

Can you please help? I cant use any of the modes like this, except stabilize and acro. Would be nice to have a reliable RTL/Land and AltHold.

2

Hi

There must be something strange with your setup. Although I+m not using 4S batteries my small PixRacer quad behaves fantastically in all modes. I’m using 2204-2300kV with 6040 propellers on 3SRobocat parameter 9-10-2016.param.zip (4.0 KB)

I’m attaching my parameters ONLY to serve as guidance.

Flight performance is quite reasonable, although I haven’t done auto-tune. These videos were made mostly on either Stab or AltHold, with brief excursions to PosHold.

The Throw tests were done also but the GoPro battery was dead :slight_smile:

3

Hi, thanks for the params, im going to compare them. Im using hand calibrated PIDs.
Good to hear this should work.
I moved from 3s because my quad is quite heavy (around 700g with batt) and i wanted a bit more power. I had good results with alt hold on 4.3-rc 2-3 but had other issues.
Thanks again :slight_smile:

4

The Quad you see on the videos and is using those parameters is 635g with 3S 2200mAh 45C NanoTech batteries

And Emergency Stop works :slight_smile:

5

Just finished watching the videos, awesome :slight_smile:
I currently comparing the params,
Do you really have MOT_THST_HOVER at 0,13100241? With 6040 on 3S?
Mine is set to 0.25, because the docs says thats the minimum

Beside of this, i dont find any other major difference. Did you use hover auto learn?

6

I was surprised with that too, but Hover auto learn is always “on” :slight_smile:

7

I will try to set it to 0.19, that would be my ‘good’ value with 5045 (gemfan).
But i have to be careful, because if it resets to default, 0.5, the quad will just disappear in a moment. :smiley: My biggest fear is that is flies away, uncontrollably.

Indeed, you have hov.learn enabled, was yet hiding between the other params

8

Just set one switch to RTL and don’t be afraid to use it :slight_smile:

On my radio I have a 3 position switch that goes RTL and Land on each position, so that I can be “courageous” with settings (and I have also a switch for Emergency Stop :slight_smile: )

9

@LuisVale: just finished testing the hover learn, resulted in: MOT_THST_HOVER 0,1962113
The quad flies great! Thank you for your suggestions and pointing me to the right direction.

Sooo, as for a TL;DR:
an overpowered mini quad can fly well; enable hover learn confidently, take off slowly for first.
The min-max values are not enforced for this. I’m flying fine with 0.196…

10

Glad I could help. Now at 0.13 my quad goes faster than yours :slight_smile: