WIRELESS POSITION SENSING USING MAGNETIC FIELD OF TWO TRANSMITTERS

• US 20150308861A1
• Filed: 04/27/2015
• Published: 10/29/2015
• Est. Priority Date: 04/25/2014
• Status: Abandoned Application

• Current Assignee: Purdue Research Foundation (The Trustees of Purdue University (d/b/a Purdue University))
• Original Assignee: Purdue Research Foundation (The Trustees of Purdue University (d/b/a Purdue University))
• Inventors: Jung, Byunghoo, Singh, Mohit
• Application Number:
  US14/697,042
• Publication Number:
  US 20150308861A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01C 21/206 specially adapted for indoor navigation
• CPC Class Codes: G01D 5/2073 by movement of a single coil with respect to two or more coils
• CPC Class Codes: G01R 33/0206 Three-component magnetometers

Abstract

A positioning system for determining the location of a receiver relative to a transmitter. The system includes two transmitting coils configured to transmit a periodic signal with a respective selected frequency during a positioning event, wherein the frequencies of the two signals transmitted by the two transmitting coils during the positioning event are different. A receiver includes a sensing unit for measuring the magnetic field vectors produced by the two simultaneously transmitting coils. A computing unit is configured to use the measured magnetic field vectors to calculate the position and orientation of the receiver with respect to the transmitter'"'"'s coordinate frame.

Claims

1. A positioning system, comprising:

a) two transmitting coils, each coil configured to transmit a periodic signal with a respective selected frequency during a positioning event, wherein the frequencies of the two signals transmitted by the two transmitting coils during the positioning event are different;

b) a receiver including a sensing unit for measuring the magnetic field vectors produced by the two simultaneously transmitting coils; and

c) a computing unit configured to use the measured magnetic field vectors to calculate the position and orientation of the receiver with respect to the transmitter'"'"'s coordinate frame.

2. The system according to claim 1, wherein the sensing unit includes a tri-axis magnetic sensor.

3. The system according to claim 1, in which one or both of the transmitting coils are integrated into a mobile electronic device, and both the transmitting coils and sensing unit move simultaneously, and wherein the orientation of the transmitting coil(s) in the earth'"'"'s coordinate system is provided to the computing unit in the receiver at real time.

4. The system of claim 1, comprising a plurality of receivers which operate simultaneously and independently.

5. The system according to claim 1, wherein the computing unit is integrated in the receiver.

6. The system according to claim 1, wherein the computing unit is located remotely from the receiver, the receiver transmits the measured magnetic field vector in the receiver'"'"'s own coordinate system to the computing unit through a wired or wireless channel.

7. The system according to claim 1, wherein the magnetic sensor includes three planar coils oriented orthogonally to each other.

8. The system according to claim 1, wherein the receiver comprises a plurality of tri-axis magnetic sensors for measuring the magnetic field of the transmitting coil.

9. The system according to claim 1, wherein the receiver comprises a a solid-state compass to measure the receiver orientation in the earth'"'"'s coordinate system, the receiver orientation is transmitted to the computing unit.

10. The system according to claim 1, wherein the transmitting coils are integrated into a computing unit, the position data of the receiver is transmitted to the computing unit.

11. The system according to claim 10, wherein the computing unit comprises at least one of a television, mobile phone, tablet computer, notebook computer, desktop computer, wearable device and a video gaming device.

12. The system according to claim 1, wherein the receiver is integrated into the computing unit, allowing the position of the computing unit with respect to the transmitting coils to be determined.

13. The system according to claim 1, wherein the receiver is configured as a stand-alone unit, the receiver sends the position and orientation data to the computing unit through a wired or wireless channel.

14. The system according to claim 1, wherein the transmitting coils are configured to transmit a beacon signal, the beacon signal including a periodic signal portion for determining the receiver position and an auxiliary signal portion.

15. The system according to claim 14, wherein the auxiliary signal portion includes at least one of coil identification information, coil orientation, transmitting signal frequency, transmitting coil size, and transmitting coil shape.

16. The system according to claim 1, further comprising:

a plurality of pairs of transmitting coils, each pair configured to transmit at a different set of frequencies than the other pairs; and

a plurality of receivers, each of said receivers configured to receive signals from one of said pairs.

17. The system according to claim 1, wherein the computing unit is configured to perform an initial estimate of the receiver position and orientation of the receiver, and then evaluate a plurality of positions around the initial estimated position.

18. The system according to claim 17, wherein the computing unit is further configured to evaluate errors between measured field values for the plurality of positions and predicted field values.

19. The system according to claim 18, the computing unit further configured to select a second estimated position from the plurality of positions, the second estimated position having the smallest field error compared to the remaining plurality of positions.

20. A method of determining a position of a receiver in relation to a pair of transmitting coils, comprising:

simultaneously transmitting a pair of periodic signals during a positioning event using the pair of transmitting coils, the periodic signals having different frequencies;

using a receiver, sensing a magnetic field vector produced by the transmitting coils;

using a computing device, estimating a position and orientation of the receiver with respect to the transmitter coils'"'"' coordinate system using the measured magnetic field vector from the two transmitter coils.