System And Method For Sensing Human Activity By Monitoring Impedance

• US 20110248773A1
• Filed: 04/01/2011
• Published: 10/13/2011
• Est. Priority Date: 04/08/2010
• Status: Active Grant

• Current Assignee: Disney Enterprises Incorporated (The Walt Disney Company)
• Original Assignee: Disney Enterprises Incorporated (The Walt Disney Company)
• Inventors: Loh, Jonas, Yeo, Zhiquan, Poupyrev, Ivan
• Granted Patent: US 8,975,900 B2
• Time in Patent Office: Days
• US Class Current: 327/517
• CPC Class Codes: G01R 27/02 Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant by measuring phase angle only G01R25/00
• CPC Class Codes: G06F 3/011 Arrangements for interaction with the human body, e.g. for user immersion in virtual reality blind teaching G09B21/00
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

A system for sensing human activity by monitoring impedance includes a signal generator for generating an alternating current (AC) signal, the AC signal applied to an object, a reactance altering element coupled to the AC signal, an envelope generator for converting a returned AC signal to a time-varying direct current (DC) signal, and an analog-to-digital converter for determining a defined impedance parameter of the time-varying DC signal, where the defined impedance parameter defines an electromagnetic resonant attribute of the object.

Claims

1. A system for sensing human activity by monitoring impedance, comprising:

a signal generator for generating an alternating current (AC) signal, the AC signal applied to an object;

a reactance altering element coupled to the AC signal;

an envelope generator for converting a returned AC signal to a time-varying direct current (DC) signal; and

an analog-to-digital converter for determining a defined impedance parameter of the time-varying DC signal, where the defined impedance parameter defines an electromagnetic resonant attribute of the object.

2. The system of claim 1, wherein the reactance altering element comprises a biasing capacitance configured to substantially reduce an influence of capacitance on the returned AC signal, thereby allowing determination of changes in an inductive effect on the electromagnetic resonant attribute.

3. The system of claim 1, wherein the reactance altering element comprises a biasing inductance configured to substantially reduce an influence of inductance on the returned AC signal, thereby allowing determination of changes in a capacitive effect on the electromagnetic resonant attribute.

4. The system of claim 1, wherein the electromagnetic resonant attribute is a resonant frequency.

5. The system of claim 1, wherein the defined impedance parameter is a local minimum of a trace of the time-varying DC signal.

6. The system of claim 5, wherein the local minimum corresponds to the resonant frequency of the object.

7. The system of claim 1, wherein the defined impedance parameter is an amplitude of the time-varying DC signal.

8. The system of claim 1, further comprising a memory for storing the defined impedance parameter of the object.

9. The system of claim 8, further comprising associating the defined impedance parameter with the object.

10. A system for sensing human activity by monitoring impedance, comprising:

a signal generator for generating an alternating current (AC) signal, the AC signal applied to an object;

a reactance altering element coupled to the AC signal;

an envelope generator for converting a returned AC signal to a time-varying direct current (DC) signal; and

an analog-to-digital converter for determining a local minimum of the time-varying DC signal, where the local minimum defines a resonant frequency of the object.

11. The system of claim 10, wherein the reactance altering element comprises a biasing capacitance configured to substantially reduce an influence of capacitance on the returned AC signal, thereby allowing determination of changes in an inductive effect on the resonant frequency.

12. The system of claim 10, wherein the reactance altering element comprises a biasing inductance configured to substantially reduce an influence of inductance on the returned AC signal, thereby allowing determination of changes in a capacitive effect on the resonant frequency.

13. The system of claim 10, further comprising a memory for storing the resonant frequency of the object.

14. The system of claim 10, further comprising associating the resonant frequency with the object.

15. A method for sensing human activity by monitoring impedance, comprising:

generating an alternating current (AC) signal;

applying the AC signal to an object through a reactance altering element;

receiving a returned AA signal′

converting the returned AC signal to a time-varying direct current (DC) signal; and

determining a defined impedance parameter of the time-varying DC signal, where the defined impedance parameter defines an electromagnetic resonant attribute of the object.

16. The method of claim 15, further comprising substantially reducing an influence of capacitance on the returned AC signal, thereby allowing determination of changes in an inductive effect on the electromagnetic resonant attribute.

17. The method of claim 15, further comprising substantially reducing an influence of inductance on the returned AC signal, thereby allowing determination of changes in a capacitive effect on the electromagnetic resonant attribute.

18. The method of claim 15, wherein the electromagnetic resonant attribute is a resonant frequency.

19. The method of claim 15, wherein the defined impedance parameter is a local minimum of a trace of the time-varying DC signal.

20. The method of claim 19, wherein the local minimum corresponds to the resonant frequency of the object.

21. The method of claim 15, wherein the defined impedance parameter is an amplitude of the time-varying DC signal.

22. The method of claim 15, further comprising storing the defined impedance parameter of the object.

23. The method of claim 22, further comprising associating the defined impedance parameter with the object.