Multiwii Automatic Altitude Hold, no PIDs, source and video

[ahodel]

Here's a video of a 450 quad and an octo running my automatic altitude hold code for Multiwii 2.3.



It's a complete rewrite of the BARO PID loop and does away with the need to tune and/or set PID's for AltHold/BARO. Everything is automatically adjusted based on variance.

Grab IMU.cpp from https://github.com/andrewhodel/MW23/raw/master/IMU.cpp and replace your local Multiwii 2.3 IMU.cpp with it then flash.

Commented code at https://github.com/andrewhodel/MW23/blo ... U.cpp#L339

Both the quad and octo in this video are running on a Crius AIOP v2 with only the Barometer for Altitude Hold.

[ahodel]

Here's a plot of the important data in windy conditions, it should help explain how it works.

Please test it out and give feedback.

[brm]

very nice example of an adaptive control!

[sismeiro]

Hi,

It seems very good. Let's wait and see if more people test this mod and if Alex is also happy with it to include it before 2.4 release.

Regards,
Luis Sismeiro

[brm]

Here's a plot of the important data in windy conditions, it should help explain how it works.

Please test it out and give feedback.

graph.png

i hope to test it this week. if possible i create a video.
this little framework can also be used to autotune the regular pid settings.
then it needs a bit more code but this is overseeable.

[vapourium]

Hi, ive replaced the IMU.cpp file and when trying to compile the sketch i get a long list of errors. Is there anything else i need to change in the sketch ive tryed this with mw2.3 and mw2.3 navib7 and both give errors.

[mahomedia]

Is it possible to achieve alt hold like APM. How APM holds altitude? What can we do about this?

[PropNut]

This seems to work well on a Hobby King MultiWii 328P. I tried it with V2.3, and R1648. It holds within approximately 3' (1m) I'm going to look for some capacitors to try the "Baro Power Filter" described here: http://www.multiwii.com/forum/viewtopic.php?f=17&t=5595
Edit: Power filtering didn't help on this board. I posted a little more info in the above thread.