If you have a UAV DevBoard
, and are anxious to do some flying with it, you should skip the GentleNav firmware and wait for MatrixNav, it is almost done, and will perform a couple of orders of magnitude better than GentleNav.
GentleNav was originally developed for my previous board, which used the ET312 GPS, 2 gyros, and 2 accelerometers. The algorithm was rather simple, but worked well enough and I used it for several years.
This season I decided to design a better board to use 3 gyros and 3 accelerometers to improve performance. Recently, I have been working with Paul Bizard on a "direction cosine matrix"
approach to estimating orientation. It shows great promise, and is almost done.
In the meantime, I thought that owners of the new board would want something to fly with, so I ported the GentleNav firmware from my previous board to the new one. Today was the first day I actually flew it, up until now I have been doing bench testing.
Well, GentleNav does not work as well on the new board as it did on the old board. I traced the problem to the EM-406. It turns out that the dynamic response of the EM-406 is not nearly as good as that of the ET312. It takes the EM-406 around 15 seconds to respond to a 90 degree turn, while the ET312 responds almost instantly. Because of this large dynamic time lag, the GentleNav firmware is not stable in the return-to-launch mode.
I could probably experiment with the feedback gains and get GentleNav to work with the EM-406, but since MatrixNav is almost done, I have decided to declare GentleNav to be obsolete and to focus my time on finishing MatrixNav, which should be available in a few days, a couple of weeks at the most. MatrixNav will completely resolve the issue with the dynamic delay, since it uses mainly the gyros rather than the GPS for direction information. The direction cosine matrix algorithm has a convenient way to compensate for GPS delay. MatrixNav is almost done, but I want to perform extensive flight testing before releasing it.
So I suggest you wait for MatrixNav before using your UAV DevBoard in flight. Of course, if you do not want to wait, you are welcome to experiment with GentleNav, but I do not recommend it.
In the meantime, you might want to try the roll-pitch-yaw demo
to gauge what the performance of MatrixNav might be.