In the minimu9-ahrs sketch, the accelerometer x-axis is assigned a negative sign (-1), despite being oriented forward in both of the cases shown. Could you explain why this is the case? I would have expected a (+1) instead.
I don’t really remember why it ended up being negative; that was probably just what I had to use to make the code work when I adapted it for the MinIMU. It’s possible the original sf9domahrs or ArduIMU code expected something to be the reverse of what it was (e.g. it was expecting a “down” vector instead of an acceleration vector).