Systems and methods for computing a position of a magnetic target

• US 9,625,535 B2
• Filed: 08/07/2013
• Issued: 04/18/2017
• Est. Priority Date: 08/07/2013
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Cadugan, Bryan, Rice, Jim
• Primary Examiner(s): Koval, Melissa
• Assistant Examiner(s): Monsur, Nasima
• Application Number:
  US13/960,910
• Publication Number:
  US 20150042320A1
• Time in Patent Office: 1,350 Days
• Field of Search: 32420722, 32420723, 3242072, 32420721, 324252, 324251, 32420713, 32420711, 324247, 32420724, 324 7611, 32420725, 32420726, 257E29323, 257421, 257427, 335284, 335302
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01R 33/06 using galvano-magnetic devices
• CPC Class Codes: G01R 33/075 Hall devices configured for spinning current measurements

Abstract

In embodiments, three magnetic field sensing elements are arranged equidistantly from each other to define a plane and a central axis perpendicular to the plane. The magnetic field sensing elements are configured to generate a respective output signal representing proximity of a magnetic target that is proximate to the central axis and capable of moving relative to the central axis. A processor circuit is coupled to receive output signals from each of the sensors and configured to calculate a position of the magnetic target relative to the plane.

Claims

1. A system comprising:

exactly three magnetic field sensing elements arranged in a non-collinear arrangement to define a plane having two dimensions, the magnetic field sensing elements each configured to generate a respective output signal representing a respective distance of a magnetic target from the respective magnetic field sensing element, wherein the magnetic target has a freedom of translational movement in at least the two dimensions of the plane;

a pivotal member coupled to the magnetic target, wherein the magnetic target is fixedly attached to the pivotal member and does not move relative to the pivotal member, the pivotal member positioned so that movement of a proximate end of the pivotal member causes proportional translational movement of the magnetic target in the two dimensions of the plane; and

a processor circuit coupled to receive output signals from each of the sensors and configured to calculate a translational location of the magnetic target within the two dimensions of the plane.

2. The system of claim 1 wherein the pivotal member has a pivot point on a central axis around which the magnetic field sensing elements are arranged.

3. The system of claim 2 wherein the pivotal member comprises an elongate member that, in the absence of an external force, returns to a position parallel to the central axis.

4. The apparatus of claim 1 wherein the pivotal member comprises a joystick lever.

5. The system of claim 1 wherein the processor circuit provides the location of the magnetic target by providing an X coordinate and a Y coordinate representing a translational location within the plane.

6. The apparatus of claim 1 wherein the processor provides the translational location of the magnetic target by providing a tilt value of the member and a direction of tilt of the pivotal member.

7. The system of claim 1 wherein the magnetic target comprises a permanent magnet.

8. The system of claim 1 wherein the magnetic field sensing elements comprise Hall Effect elements, giant magnetoresistance elements, or both.

9. The apparatus of claim 1 wherein the magnetic field sensing elements are arranged at regular increments about a central axis.

10. A method comprising:

arranging exactly three magnetic field sensing elements in a non-collinear arrangement to define a plane having two dimensions;

generating, by each magnetic field sensing element, an output signal representing a distance of a magnetic target to the respective magnetic field sensing element, wherein the magnetic target has a freedom of translational movement at least in the two dimensions of the plane;

pivoting a pivotal member which, when moved, causes the translational movement of the magnetic target in at least the two dimensions, wherein the magnetic target is fixedly attached to the pivotal member and does not move relative to the pivotal member; and

calculating, by a processor coupled to receive the output signals from each of the magnetic field sensing elements, a translational location of the magnetic target in the two dimensions of the plane based on the signals from the three magnetic field sensing elements.

11. The method of claim 10 wherein the pivotal member comprises a joystick lever and moving the magnetic target comprises moving the joystick lever.

12. The method of claim 10 wherein calculating the translational location includes providing an X coordinate and a Y coordinate representing the translational location within the plane.

13. The method of claim 10 wherein calculating the location includes providing a tilt value of the pivotal member and a direction of tilt of the pivotal member.

14. The method of claim 10 further comprising arranging the magnetic field sensing elements at regular increments about a central axis.

15. A computer program, stored in a non-transitory computer readable storage medium, which when executed by a processor causes the processor to perform operations comprising:

receiving signals from exactly three magnetic field sensing elements that are arranged in a non-collinear arrangement to define a plane having two dimensions, each signal representing a respective distance between a magnetic target and a respective magnetic field sensing element, wherein the magnetic target has a freedom of translational movement in at least the two dimensions of the plane;

computing a translational location of the magnetic target as a function of the three signals; and

providing output signals representing the translational location of the magnetic target in Cartesian coordinates;

wherein the magnetic target is fixedly attached and does not move relative to a pivotal member, and translational movement of the magnetic target in the two dimensions is caused by movement of the pivotal member.

16. An apparatus comprising:

three inputs each capable of receiving a signal from a respective one of exactly three magnetic field sensing elements, the signal representing proximity of a magnetic target to the respective magnetic field sensing element, wherein the magnetic target has a translational freedom of movement in at least two dimensions of a plane defined by the exactly three magnetic field sensing elements

a pivotal member coupled to the magnetic target, wherein the magnetic target is fixedly attached to the pivotal member and does not move relative to the pivotal member, the pivotal member positioned so that movement of the pivotal member causes proportional translational movement of the magnetic target in the two dimensions of the plane; and

a processor circuit configured to compute a translational location of the magnetic target within the two dimensions of the plane based on the proximity of the magnetic target to each of the magnetic field sensing elements.

17. The apparatus of claim 16 wherein the inputs are configured to receive the signals from Hall Effect elements, giant magnetoresistance elements, or both.

18. The apparatus of claim 17 wherein the apparatus further comprises a circuit for providing power to the magnetic field sensing elements.

19. The apparatus of claim 16 wherein the processor circuit is further configured to provide an X coordinate and a Y coordinate representing the translational location of the magnetic target.

20. The apparatus of claim 16 wherein the processor circuit is further configured to provide the translational location of magnetic target in a format compatible with a game or a simulation.

21. The apparatus of claim 16 wherein the apparatus is configured to be installed in a joystick.