I took out our new altitude hold code with my mini folding quad from Hovership. I'm pretty pleased with the results. The video also came out quite smoothly which is nice.
The changes include
- using the a complementary filter to fuse the vertical movement, similar to the one from Ardupilot, which provides better correction of accel bias and works quite reliably
- switch to full state control which makes vertical movement feel more locked in (same approach as axis lock)
- exponential on the throttle control allows more sensitive control in middle
See more at forums.taulabs.org (http://forum-test.taulabs.org/viewtopic.php?f=17&t=27)
Blog about quad here: http://buildandcrash.blogspot.com/2014/02/microquad-from-hovership-pro.html