Patent ID: 8411030

Claim:
A device, comprising: a body configured for manual manipulation; an inertial sensor fixed to the body and configured to supply first signals correlated to the orientation of the body with respect to a gravitational field acting on the inertial sensor; a magnetometer fixed to the body and configured to supply second signals correlated to the orientation of the body with respect to the Earth's magnetic field acting on the magnetometer; and a processor configured to determine an orientation of the body in an absolute reference system, fixed with respect to the Earth's magnetic field and to the gravitational field, on the basis of the first signals and of the second signals, the processor further configured to determine the relative co-ordinates of three first vectors that are parallel to three respective axes of the absolute reference system on the basis of the relations U 1 = - G _  - G _  U 2 = - G _ ⋀ M _  - G _ ⋀ M _ )  U 3 = - G _ ⋀ ( - G _ ⋀ M _ )  - G _ ⋀ ( - G _ ⋀ M _ )  where U 1 , U 2 , U 3 are the three first vectors, G is the Earth's gravitational field, and M is the Earth's magnetic field.