I’ve purchased the BerryIMU and I’m trying to get some correct readings using the code from python-BerryIMU-gryo-accel-compass/berryIMU.py. When I tilt the BerryIMU 90 degrees to the right I would expect X to be around 90 and Y to be around 0. X is indeed around 90, but when approaching the 90X, the readings for Y suddenly go from around zero to about 100.
I asked a question about this behaviour on robotics.stackexchange, and the answer I got was that the problem was “estimating angles in regions of instability” in which they suggest to “modify unstable equations”.
I also asked about this on the BerryIMU github page but I got no reply.