US Patent 7844415 Dynamic motion compensation for orientation instrumentation

The instant invention discloses a method for an orientation measuring instrument to isolate and separate gravitational and non-gravitational components of acceleration from accelerometer measurements by using an ambient magnetic field, typically the earth's magnetic field, as a fixed rotation reference. Using magnetic field measurements, one can track changes in orientation of a device and use that information to determine the gravitation direction, during periods when acceleration measurements include non-gravitational acceleration combined with gravitational acceleration components. In addition to determining orientation, a method and associated instrument provide a non-gravity acceleration vector of the device.