Patent ID: 7685732

Claim:
An orientation sensing apparatus, the apparatus comprising: (a) a rotatable first member having a first member orientation with respect to gravity; (b) an orientation sensor device fixed with the first member for generating orientation data relating to an orientation sensor device orientation of the orientation sensor device with respect to gravity, wherein the orientation sensor device orientation is referenced to the first member orientation, wherein the orientation sensor device is comprised of a first accelerometer for sensing a first sensed component in a first direction, wherein the orientation sensor device is further comprised of a second accelerometer for sensing a second sensed component in a second direction, wherein the orientation sensor device is further comprised of a third accelerometer for sensing a third sensed component in a third direction, and wherein the first direction, the second direction and the third direction are substantially perpendicular to each other; (c) a rotation sensor device for generating rotation data relating to rotation of the first member; and (d) a first processor, wherein the apparatus is configured to assemble sets of sensor data, wherein each set of sensor data is comprised of the orientation data and the rotation data, wherein the first processor is configured to process the sets of sensor data in order to generate sets of corrected orientation data each comprising a corrected first sensed component, a corrected second sensed component and a corrected third sensed component, and wherein the sets of corrected orientation data are comprised of the orientation data which has been corrected using the rotation data to reduce the effects of rotation of the first member and misalignment of the orientation sensor device.