AUTO-CALIBRATION OF ORIENTATION SENSING SYSTEMS
First Claim
1. An electronic device with an orientation sensing system for determining an orientation of the device in operational use of the devicethe orientation sensing system comprising:
- a first sensor comprising a 2D magnetometer or a 3D magnetometer for supplying first vectors representative of sensed magnetic field vectors that include earth-magnetic field vectors;
a second sensor comprising a 2D accelerometer or a 3D accelerometer for supplying second vectors representative of sensed acceleration vectors that include the gravity field vectors; and
calibration means coupled to the first and second sensors for calibrating the sensing system for operational use, wherein the calibration means is operable to;
use the second vectors to constrain a range of possible directions of corresponding ones of the earth-magnetic field vectors to be determined per corresponding ones of multiple orientations of the device; and
numerically solve a set of equations involving first quantities representative of the first vectors and second quantities representative of the second vectors, wherein the set includes, for each of the first quantities, a corresponding equation that comprises a term that is equivalent to a matrix multiplication of a parameter matrix with the corresponding earth-magnetic field vector and wherein the set further comprises second equations specifying the magnitude of the earth magnetic field vector per corresponding one of the multiple orientations, and third equations specifying the value of the dot product of the earth magnetic field vector with the gravity field vector per corresponding one of the multiple orientations.
10 Assignments
0 Petitions
Accused Products
Abstract
An electronic device has an orientation sensing system for determining an orientation of the device. The system comprises a magnetometer and an accelero meter. The system further has calibration means to calibrate the sensing system for operational use. The accelerometer supplies measurements used to constrain a range of possible directions of the external magnetic field to be determined. The calibration means numerically solves a set of equations and is equally well useable for a 2D or 3D magnetometer in combination with a 2D or 3D accelerometer.
81 Citations
15 Claims
-
1. An electronic device with an orientation sensing system for determining an orientation of the device in operational use of the device
the orientation sensing system comprising: -
a first sensor comprising a 2D magnetometer or a 3D magnetometer for supplying first vectors representative of sensed magnetic field vectors that include earth-magnetic field vectors; a second sensor comprising a 2D accelerometer or a 3D accelerometer for supplying second vectors representative of sensed acceleration vectors that include the gravity field vectors; and calibration means coupled to the first and second sensors for calibrating the sensing system for operational use, wherein the calibration means is operable to; use the second vectors to constrain a range of possible directions of corresponding ones of the earth-magnetic field vectors to be determined per corresponding ones of multiple orientations of the device; and numerically solve a set of equations involving first quantities representative of the first vectors and second quantities representative of the second vectors, wherein the set includes, for each of the first quantities, a corresponding equation that comprises a term that is equivalent to a matrix multiplication of a parameter matrix with the corresponding earth-magnetic field vector and wherein the set further comprises second equations specifying the magnitude of the earth magnetic field vector per corresponding one of the multiple orientations, and third equations specifying the value of the dot product of the earth magnetic field vector with the gravity field vector per corresponding one of the multiple orientations. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. (canceled)
-
8. A method of calibrating an orientation sensing system operable to determine an orientation of the system, wherein the system, comprises:
-
a first sensor comprising a 2D magnetometer or a 3D magnetometer for supplying first vectors representative of sensed magnetic field vectors that include the earth-magnetic field vectors; and a second sensor comprising a 2D accelerometer or a 3D accelerometer for supplying second vectors representative of sensed acceleration vectors that include the gravity field vectors; wherein the method comprises; using the second vectors to constrain a range of possible directions of corresponding ones of the earth-magnetic field vectors to be determined per corresponding ones of multiple orientations of the system; and numerically solving a set of equations involving first quantities representative of the first vectors and second quantities representative of the second vectors, wherein the set includes, for each of the first quantities, a corresponding equation that comprises a term that is equivalent to a matrix multiplication of a parameter matrix with the corresponding earth-magnetic field vector, and wherein the set further comprises second equations specifying the magnitude of the earth-magnetic field vector per corresponding one of the multiple orientations, and third equations specifying the value of the dot product of the earth-magnetic field vector with the gravity field vector per corresponding one of the multiple orientations. - View Dependent Claims (9, 10, 11, 12, 13, 14)
-
-
15-19. -19. (canceled)
Specification