this is way over my head, so you may just tell me I am dead wrong.
I have recently glued an MWii board on my flybarless helicopter and got it maidened with a friend's help (viewtopic.php?f=8&t=1562&start=40#p15319). But the tail/yaw response differs from what a good classic heading hold gyro can do. Currently the yaw-PID is tuned to work as a good (acceptable) rate gyro (PID=6.5, 0.009, 80).
Now when flying heli, the heading hold (HH) is far superior to rate mode. It holds direction like it is kinda memorized and returns to that direction until told otherwise. In comparison, a rate gyro will only try to keep a steady direction by minimizing bounces - but first gust and original direction is lost forever.
Incindentally I stumbled upon a HH gyro project over at RCG. The author discusses the PID implementation for both rate and HH and shortcomings in some detail. He also claims to have added some extra debounce feature to overcome the PID shortcoming, but is not willing to reveal the nature of it. He has published some of his thoughts and findings here
Further discussion hereThe Heli Gyro as a Controller: Theory and Experiment http://www.rcgroups.com/forums/showthread.php?t=1538273
Gyro GA250 + alternative Firmware: The Best of the Cheap!? http://www.rcgroups.com/forums/showthread.php?t=1610075
One of his claims (or what I understood) was to decrease P & increase I for HH. When we tried this on my heli the tail became unstable/oscillating.
So what do you think, is this HH something that was good to have for all multicopters and how can we tune the yaw-PID for a better HH? Or do we need another (extended) algorithm than traditional PID? Ideas, comments?