SYSTEMS AND METHODS FOR DETERMINING ACCELERATION BASED ON PHASE DEMODULATION OF AN ELECTRICAL SIGNAL

• US 20150301077A1
• Filed: 04/15/2015
• Published: 10/22/2015
• Est. Priority Date: 04/16/2014
• Status: Active Grant

• Current Assignee: Cirrus Logic Incorporated
• Original Assignee: Cirrus Logic Incorporated
• Inventors: Melanson, John L., Jiang, Ruoxin, Hodapp, Stephen T., Tucker, John C., Bhattacharya, Anindya, Holley, Roderick D.
• Granted Patent: US 10,571,484 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01P 15/125 by capacitive pick-up

Abstract

In accordance with embodiments of the present disclosure, an apparatus for measuring acceleration may include a spring-mounted mass, a positional encoder configured to measure a position of the spring-mounted mass and output one or more signals indicative of a sine and a cosine of the position, a driver to set and maintain an oscillation of the spring-mounted mass, and a decoder configured to process the one or more signals to calculate an acceleration of the spring-mounted mass.

Claims

1. An apparatus for measuring acceleration, comprising:

a spring-mounted mass;

a positional encoder configured to measure a position of the spring-mounted mass and output one or more signals indicative of a sine and a cosine of the position;

a driver to set and maintain an oscillation of the spring-mounted mass; and

a decoder configured to process the one or more signals to calculate an acceleration of the spring-mounted mass.

2. The apparatus of claim 1, further comprising a feedback control system to control a magnitude of the oscillation in such a manner to optimize measurement and accuracy of the acceleration.

3. The apparatus of claim 2, wherein a magnitude of the oscillation is such that the one or more signals have a substantially zero direct current component.

4. The apparatus of claim 1, wherein the decoder is further configured to:

process the one or more signals to calculate a phase angle of the position as a function of time; and

low-pass filter the phase angle of the position as a function of time to filter out the oscillation of the spring-mounted mass and extract the acceleration from the phase angle of the position as a function of time.

5. The apparatus of claim 1, wherein the driver comprises a mechanical driver.

6. The apparatus of claim 1, wherein the driver comprises an electro-static driver.

7. The apparatus of claim 1, wherein the apparatus further comprises a stator mechanically coupled to the spring-mounted mass such that the spring-mounted mass oscillates relative to the stator.

8. The apparatus of claim 7, wherein:

the stator comprises one or more first features; and

the spring-mounted mass comprises one or more second features, each of the one or more second features corresponding to a respective one of the one or more first features;

further wherein the one or more first features and one or more second features are arranged such that as the spring-mounted mass oscillates relative to the stator, a capacitance between each of the one or more second features and their respective first features varies.

9. The apparatus of claim 8, wherein the capacitance is indicative of at least one of a sine of the position of the spring-mounted mass and the cosine of the position of the spring-mounted mass.

10. An integrated circuit comprising:

an input for receiving one or more positional encoder signals indicative of a sine and cosine of a position of an oscillating spring-mounted mass; and

a decoder configured to process the one or more positional encoder signals to calculate an acceleration of the oscillating spring-mounted mass.

11. The integrated circuit of claim 10, further comprising a feedback control system to control a magnitude of an oscillation of the oscillating spring-mounted mass in such a manner to optimize measurement and accuracy of the acceleration.

12. The integrated circuit of claim 11, wherein a magnitude of the oscillation is such that the one or more positional encoder signals have a substantially zero direct current component.

13. The integrated circuit of claim 10, wherein the decoder is further configured to:

process the one or more positional encoder signals to calculate a phase angle of the position as a function of time; and

low-pass filter the phase angle of the position as a function of time to filter out the oscillation of the spring-mounted mass and extract the acceleration from the phase angle of the position as a function of time.

14. A method comprising:

receiving one or more positional encoder signals indicative of a sine and cosine of a position of an oscillating spring-mounted mass; and

processing the one or more positional encoder signals to calculate an acceleration of the oscillating spring-mounted mass.

15. The method of claim 14, further comprising a feedback control system to control a magnitude of an oscillation of the oscillating spring-mounted mass in such a manner to optimize measurement and accuracy of the acceleration.

16. The method of claim 15, wherein a magnitude of the oscillation is such that the one or more positional encoder signals have a substantially zero direct current component.

17. The method of claim 14, further comprising:

processing the one or more positional encoder signals to calculate a phase angle of the position as a function of time; and

low-pass filtering the phase angle of the position as a function of time to filter out the oscillation of the spring-mounted mass and extract the acceleration from the phase angle of the position as a function of time.

18. The method of claim 14, further comprising measuring the position of the oscillating spring-mounted mass with a positional encoder configured to generate the one or more positional encoder signals.

19. The method of claim 14, further comprising setting and maintaining an oscillation of the oscillating spring-mounted mass using a driver.

20. The method of claim 19, wherein the driver comprises a mechanical driver.

21. The method of claim 19, wherein the driver comprises an electro-static driver.