System and method for using magnetic sensors to track the position of an object

• US 8,321,173 B2
• Filed: 08/24/2005
• Issued: 11/27/2012
• Est. Priority Date: 08/25/2004
• Status: Expired due to Fees

• Current Assignee: Andrea L.M. Baker, Daniel I. Wallance, Wojciech Krajewski
• Original Assignee: Andrea L.M. Baker, Daniel I. Wallance, Wojciech Krajewski
• Inventors: Wallance, Daniel I., Baker, Andrea L. M., Krajewski, Wojciech
• Primary Examiner(s): Huynh, Phuong
• Application Number:
  US11/210,587
• Publication Number:
  US 20060061354A1
• Time in Patent Office: 2,652 Days
• Field of Search: 702/150, 702/95, 702 35- 40, 702151-155, 702/104, 702/105, 702186-188, 345/163, 345/158, 600/517, 600/593, 600/302, 600/547, 700/9, 700/10, 73/12.3, 73/17.9, 324/207.15, 324/658, 324/659, 324/660, 324/661, 324/662, 324/687, 324/457, 324/207.22, 342/448, 342/465, 342/450, 342/463, 340/539.13, 340/572.1, 455/456.1, 455/456.5
• US Class Current: 702/150
• CPC Class Codes: G01B 7/003 for measuring position, not involving coordinate determination coordinate measuring G01B7/004
• CPC Class Codes: G06F 3/0346 with detection of the device orientation or free movement in a 3D space, e.g. 3D mice, 6-DOF [six degrees of freedom] pointers using gyroscopes, accelerometers or tilt-sensors
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

A method is provided for tracking an object'"'"'s position. One or more semiconductor-based sensors obtain measurements of an energy field associated with the object. A processor applies an algorithm to the measurements to generate one or more values representing a position of the object in a coordinate system. The energy field may comprise a magnetic field, for example. The object may comprise a magnet, for example.

Claims

1. A computer cursor position tracking system, comprising:

a computer;

a display device coupled to the computer;

a three dimensional tracking volume comprising at least first, second, and third orthogonal platforms physically connected to define a three-dimensional space having a predetermined volume;

at least first, second, and third magnetoresistive integrated circuit sensors mounted to the first, second, and third platforms, respectively, the sensors being orthogonally aligned;

a computer mouse coupled to the computer, the computer mouse comprising a permanent magnet generating a magnetic field, the permanent magnet being freely movable in three dimensions within the tracking volume;

the first, second, and third magnetoresistive integrated circuit sensors configured to detect respective components of an intensity of the magnetic field generated by the permanent magnet, wherein the sensors are separate from the at least one permanent magnet, the detected components of the intensity being dependent, at least in part, on the proximity of the permanent magnet to a respective sensor;

the computer comprising at least one processor configured to;

determine the position of the permanent magnet within the tracking volume based, at least in part, on the detected magnetic field; and

display a computer cursor on the display device in a position corresponding to the determined position of the permanent magnet within the tracking volume.

2. The system of claim 1, further comprising:

a storage configured to store a look-up table correlating coordinates representing a location and respective sets of one or more values representing components of the detected magnetic field;

the at least one processor being further configured to;

determine the position of the movable permanent magnet based, at least in part, on the detected magnetic field and the look-up table.

3. The system of claim 1, wherein the processor is configured to activate an alarm if the permanent magnet is moved outside of the tracking volume.

4. The system of claim 1, wherein the first, second, and third magnetoresistive integrated circuit sensors each comprise three orthogonally aligned magnetoresistive integrated circuit sensors supported on each of the first, second, and third platforms.

5. The system of claim 4, further comprising:

first, second, and third circuit boards to support each of the three orthogonally aligned magnetoresistive integrated circuit sensors, respectively, the first, second, and third circuit boards being supported by the first, second, and third platforms, respectively.

6. The system of claim 1, wherein the at least one processor is configured to determine the position of the permanent magnet within the tracking volume by a multithreaded program architecture.

7. The system of claim 1, wherein the computer mouse comprises a ring-shaped device to be moved by a body part of a user, the ring-shaped device including the permanent magnet.

8. The system of claim 7, wherein the body part is a finger of the user and the ring-shaped device is configured to be worn on a user'"'"'s finger.

9. The system of claim 1, further comprising:

first, second, and third circuit boards to support the first, second, and third sensors, respectively, the first, second, and third circuit boards being supported by the first, second, and third platforms, respectively.

10. The system of claim 2, wherein the at least one processor is configured to determine the position of the permanent magnet based, at least in part, on the lookup table and a best fit equation.

11. A method for controlling a position of a cursor on a computer display, the method comprising:

defining a three dimensional tracking volume by at least first, second, and third orthogonal platforms physically connected to define a three-dimensional space, the first, second, and third platforms having mounted thereto at least first, second and third stationary magnetoresistive integrated circuit sensors, respectively, the first, second, and third sensors being orthogonally aligned, and the tracking volume having a predetermined volume;

moving a computer mouse comprising a permanent magnet within the three-dimensional space of the tracking volume by a body part of a user, the computer mouse being freely movable within the tracking volume;

detecting by the first, second, and third magnetoresistive integrated circuit sensors respective components of an intensity of a magnetic field generated by the permanent magnet of the computer mouse, the respective detected components of the intensity being dependent, at least in part, on the proximity of the permanent magnet to a respective sensor;

determining the position of the permanent magnet within the tracking volume in three-dimensions based, at least in part, on the respective detected components of the magnetic field detected by the first, second, and third magnetoresistive integrated circuit sensors; and

displaying a computer cursor on the computer display in a position corresponding to the determined position of the permanent magnet within the tracking volume.

12. The method of claim 11, comprising determining the position of the permanent magnet within the tracking volume by:

examining a look-up table correlating at least one first set of one or more coordinates representing a location within the tracking volume, a set of one or more values representing the respective detected components of a magnetic field, and at least one second set of one or more coordinates representing a location on a computer display corresponding to the location within the tracking volume.

13. The method of claim 11, wherein the first, second, and third sensors are mounted on first, second, and third circuit boards, respectively, mounted on the first, second, and third platforms, respectively.

14. The method of claim 11, wherein the computer mouse comprises a ring-shaped device and the permanent magnet is part of the ring-shaped device, the method further comprising:

moving the ring-shaped device within the tracking volume by the user'"'"'s body part.

15. The method of claim 14, wherein the body part is a finger of the user and the ring-shaped device is configured to be worn on a user'"'"'s finger, the method comprising:

moving the ring-shaped device within the tracking volume by the user'"'"'s finger.

16. The method of claim 11, comprising displaying the computer cursor on the computer display in a computer aided design (CAD) drawing.

17. The method of claim 11, comprising displaying the computer cursor on the computer display in a three-dimensional computer game.

18. The method of claim 11, further comprising activating an alarm if the permanent magnet is moved outside of the tracking volume.

19. The method of claim 11, wherein the first, second, and third magnetoresistive integrated circuit sensors each comprise three, orthogonally aligned magnetoresistive integrated circuits supported on each of the first, second, and third platforms, respectively.

20. The method of claim 19, further comprising:

first, second, and third circuit boards to support the three orthogonally aligned magnetoresistive integrated circuit sensors, respectively, the first, second, and third circuit boards being supported by the first, second, and third platforms, respectively.

21. The method of claim 11, comprising determining the position of the permanent magnet within the tracking volume by a processor of a computer coupled to the computer display.

22. The method of claim 12, comprising determining the position of the permanent magnet within the tracking volume based on the lookup table and a best fit equation.

23. The method of claim 14, wherein the body part is a tongue of a user, the method comprising:

moving the computer mouse by the tongue of the user, within the tracking volume.