ESTIMATING THE GRAVITY VECTOR IN A WORLD COORDINATE SYSTEM USING AN ACCELEROMETER IN A MOBILE DEVICE

摘要

An accelerometer located within a mobile device is used to estimate a gravity vector on a target plane in a world coordinate system. The accelerometer makes multiple measurements each measurement being taken when the mobile device is held stationary on the target plane and a surface of the mobile device faces and is in contact with a planar portion of the target plane. An average of the measurements is calculated. A rotational transformation between an accelerometer coordinate system and a mobile devices coordinate system is retrieved from a memory in the mobile device where the mobile devices coordinate system is aligned with the surface of the mobile device. The rotational transformation is applied to the averaged measurements to obtain an estimated gravity vector in a world coordinate system defined by the target plane.