Use OmniMount if the navX-sensor is not mounted horizontally

By default, the navX-sensor’s motion processing requires the unit be mounted horizontally, parallel to the earth’s surface; the yaw (Z) axis should be perpendicular to the earths surface.

If you need to mount navX-sensor vertically or upside-down, you will need to enable the “OmniMount” feature in order to get reliable, accurate yaw (Z) axis readings.