SYSTEMS AND METHODS FOR DETERMINING POSITION USING LIGHT SOURCES

• US 20120162633A1
• Filed: 12/22/2010
• Published: 06/28/2012
• Est. Priority Date: 12/22/2010
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Roberts, Richard D., Gopalakrishnan, Praveen
• Granted Patent: US 8,411,258 B2
• Time in Patent Office: Days
• US Class Current: 356/5.09
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves

Abstract

A positioning system and method for determining a coordinate of an object may comprise a positioning transmitter system and a positioning receiver system. The positioning transmitter system includes at least four light sources and a master anchor to modulate the light sources to emit modulated light signals each having a modulation frequency. The positioning receiver system comprises a lens to focus the light signals onto an optical sensor, an envelope detector to receive a signal from the optical sensors and provide output signals corresponding to the modulation frequency, and positioning detection circuitry. The positioning detection circuitry receives calibration data; determines at least four phase difference of arrival (PDOA) pairs based on the output signals from the envelope detector; determines at least four phase corrected PDOA pairs based on the calibration data and the PDOA pairs; determines at least four linear distance differences based on the phase corrected PDOA pairs; and determines the coordinate of the object based on the linear distance differences and the calibration data.

Claims

1. A method for determining a coordinate of an object, said method comprising:

receiving calibration data associated with each of at least four light sources;

receiving a modulated light signal transmitted from each of said at least four light sources, each of said modulated light signals having a modulation frequency;

determining at least four phase difference of arrival (PDOA) pairs based on each of said at least four modulated light signals;

determining at least four phase corrected PDOA pairs based, at least in part, on said calibration data and said at least four PDOA pairs;

determining at least four linear distance differences based on said at least four phase corrected PDOA pairs; and

determining said coordinate of said object based on said at least four linear distance differences and said calibration data.

2. The method of claim 1, further comprising transmitting said calibration data from each of said at least four light sources.

3. The method of claim 2, wherein said calibration data transmitted from each of said at least four light sources comprises a source identifier uniquely identifying a respective one of said light sources, a distribution phase shift associated with said respective one of said light sources, and a location of said respective one of said light sources.

4. The method of claim 3, further comprising modulating each of said at least four light sources, wherein said modulation frequency greater than 10 MHz, and wherein said at least four light sources each emit light having a wavelength in the visible light spectrum.

5. The method of claim 4, wherein said calibration data further comprises a modulation frequency associated with each of said at least four modulated light signals.

6. The method of claim 1, further comprising:

focusing each of said at least four modulated light signals onto a unique one of a plurality of pixels of an image array using a lens;

providing output signals from said image array corresponding to said modulation frequency for each of said at least four modulated light signals;

wherein said output signals are used to determine said at least four PDOA pairs.

7. The method of claim 1, further comprising determining a phase correction term for each of said at least four PDOA pairs.

8. The method of claim 7, wherein determining said phase correction term for each of said at least four PDOA pairs further comprises:

positioning a reference receiver system at a known location with respect to said at least four light sources;

providing position information to said reference receiver system for each of said at least four light sources;

receiving, at said reference receiver system, said at least four modulated light signals transmitted from each of said at least four light sources;

determining at least four PDOA pairs based on said at least four modulated light signals;

determining a propagation delay associated with each of said at least four PDOA pairs based on said known position of said reference receiver system; and

determining said at least four phase correction terms for each of said at least four PDOA pairs based on said at least four propagation delays, said at least four PDOA pairs, and said known modulation frequency of said at least four modulated light signals.

9. A positioning system comprising:

a positioning transmitter system comprising;

at least four light sources; and

a master anchor configured to modulate said at least four light sources such that each of said at least four light sources emits modulated light signals at a modulation frequency; and

a positioning receiver system comprising;

a lens configured to focus each of said at least four modulated light signals onto a respective one of a plurality of optical sensors;

an envelope detector configured to receive at least four sensor output signals from said optical sensors corresponding to said at least four modulated light signals and provide at least four output signals corresponding to said modulation frequency for each of said at least four modulated light signals; and

positioning detection circuitry, said positioning detection circuitry configured to;

receive calibration data associated with each of said at least four modulated light sources;

determine at least four phase difference of arrival (PDOA) pairs based on said at least four output signals from said envelope detector;

determine at least four phase corrected PDOA pairs based, at least in part, on said calibration data and said at least four PDOA pairs;

determine at least four linear distance differences based on said at least four phase corrected PDOA pairs; and

determine said coordinate of said object based on said at least four linear distance differences and said calibration data.

10. The system of claim 9, wherein said at least four light sources comprise light emitting diode (LED) lights configured to emit light having a wavelength in the visible light spectrum.

11. The system of claim 10, wherein said modulation frequency of said at least four modulated light signals is each greater than about 10 MHz.

12. The system of claim 11, wherein each of said at least four light sources is configured to transmit said calibration data.

13. The system of claim 12, wherein said calibration data transmitted from each of said at least four light sources comprises a source identifier uniquely identifying a respective one of said at least four light sources, a distribution phase shift associated with said respective one of said at least four light sources, and a location of said respective one of said at least four light sources.

14. The system of claim 13, wherein said calibration data further comprises said modulation frequency associated with each of said at least four modulated light signals.

15. The system of claim 9, wherein said positioning detection circuitry is further configured to determine a phase correction term for each of said at least four PDOA pairs.

16. An apparatus for determining a coordinate of an object based on at least four modulated light signals emitted from at least four light sources, said modulated light signals each having a modulation frequency, said apparatus comprising:

a positioning receiver system comprising;

a lens configured to focus each of said at least four modulated light signals onto a respective one of a plurality of optical sensors;

an envelope detector configured to receive at least four sensor output signals from said optical sensors corresponding to said at least four modulated light signals and provide at least four output signals corresponding to said modulation frequency for each of said at least four modulated light signals; and

positioning detection circuitry, said positioning detection circuitry configured to;

receive calibration data associated with each of said at least four light sources;

determine at least four phase difference of arrival (PDOA) pairs based on said at least four output signals from said envelope detector;

determine at least four phase corrected PDOA pairs based, at least in part, on said calibration data and said at least four PDOA pairs;

determine at least four linear distance differences based on said at least four phase corrected PDOA pairs; and

determine said coordinate of said object based on said at least four linear distance differences and said calibration data.

17. The apparatus of claim 16, wherein said positioning receiver system is included in a mobile device.

18. The apparatus of claim 16, wherein said positioning receiver system is included in a robotic device.

19. The apparatus of claim 16, wherein said calibration data transmitted from each of said at least four light sources comprises a source identifier uniquely identifying a respective one of said at least four light sources, a distribution phase shift associated with said respective one of said at least four light sources, and a location of said respective one of said at least four light sources.

20. The apparatus of claim 16, wherein said positioning detection circuitry is further configured to determine a phase correction term for each of said at least four PDOA pairs.