Multi-axis Sensor

• US 20080282801A1
• Filed: 02/13/2008
• Published: 11/20/2008
• Est. Priority Date: 05/16/2007
• Status: Active Grant

• Current Assignee: IntelliSense Software Corporation (Corning Incorporated)
• Original Assignee: IntelliSense Software Corporation (Corning Incorporated)
• Inventors: Akkaraju, Sandeep, Bloomsburgh, John Gardner, Yin, Luzhong, He, Yie
• Granted Patent: US 8,006,557 B2
• Time in Patent Office: Days
• US Class Current: 73/514.01
• CPC Class Codes: G01C 19/5642 using vibrating bars or beams
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/082 for two degrees of freedom of movement of a single mass

Abstract

A method and apparatus for sensing accelerations directed along multiple directions are provided. An embodiment comprises a sensor array comprising two sensor pairs, each of which provides an output signal based on acceleration along two orthogonal directions. The sensor pairs are so that they collectively provide an output signal for each of three mutually orthogonal directions. In some embodiments, the sensor array is augmented to provide three additional signals, each of which is based on rotation about an axis aligned with one of the three orthogonal directions.

Claims

1. A method comprising:

providing a first cantilever beam comprising a first mass, a first attachment point, and a first cantilever orientation, wherein the first mass has a first center of mass that is coplanar with a first plane, and wherein the first attachment point is coplanar with a second plane, and wherein the first plane and second plane are each substantially orthogonal to a first axis, and wherein the first plane and second plane are displaced on the first axis, and wherein the first cantilever orientation forms a first angle with a second direction that is aligned with a second axis that is orthogonal to the first axis, and further wherein the first angle is between 90 degrees and 270 degrees;

providing a second cantilever beam comprising a second mass, a second attachment point, and a second cantilever orientation, wherein the second mass has a second center of mass that is coplanar with the first plane, and wherein the second attachment point is coplanar with the second plane, and further wherein the second cantilever orientation and the second direction form a second angle that is between −

90 degrees and 90 degrees;

sensing a first motion of the first mass along a first direction that is aligned with the first axis; and

sensing a second motion of the second mass along the first direction.

2. The method of claim 1 further comprising:

providing the first cantilever beam such that the first angle is approximately 180 degrees; and

providing the second cantilever beam such that the second angle is approximately zero degrees.

3. The method of claim 1 further comprising:

imparting a first periodic motion along the first direction on each of the first mass and the second mass; and

comparing the first motion and the second motion.

4. The method of claim 1 further comprising:

imparting a first periodic motion along the first direction on each of the first mass and the second mass;

determining the frequency and phase of the first motion;

determining the frequency and phase of the second motion; and

comparing at least one of the frequency and phase of the first motion and the second motion.

5. The method of claim 4 further comprising imparting a second periodic motion along a third direction on each of the first mass and the second mass, wherein the third direction and the first direction are substantially orthogonal.

6. The method of claim 5 wherein the third direction is the second direction.

7. The method of claim 5 wherein the third direction is aligned with a third axis, and wherein the first axis, second axis, and third axis are mutually orthogonal.

8. The method of claim 1 further comprising:

providing a third cantilever beam comprising a third mass, a third attachment point, and a third cantilever orientation, wherein the third mass has a third center of mass that is coplanar with the first plane, and wherein the third attachment point is coplanar with the second plane, and wherein the third cantilever orientation forms a third angle with a third direction that is aligned with a third axis, and wherein the third angle is between 90 degrees and 270 degrees, and further wherein the first axis, second axis, and third axis are mutually orthogonal;

providing a fourth cantilever beam comprising a fourth mass, a fourth attachment point, and a fourth cantilever orientation, wherein the fourth mass has a fourth center of mass that is coplanar with the first plane, and wherein the fourth attachment point is coplanar with the second plane, and further wherein the fourth cantilever orientation and the third direction form a fourth angle that is between −

90 degrees and 90 degrees;

sensing a third motion of the third mass along the first direction; and

sensing a fourth motion of the fourth mass along the first direction.

9. The method of claim 8 further comprising providing the first cantilever beam, second cantilever beam, third cantilever beam and fourth cantilever beam such that:

the first angle is approximately 180 degrees;

the second angle is approximately zero degrees;

the third angle is approximately 180 degrees; and

the fourth angle is approximately zero degrees.

10. The method of claim 8 further comprising:

imparting a first periodic motion along the first direction on each of the first mass, second mass, third mass, and fourth mass;

comparing the first motion and the second motion; and

comparing the third motion and the fourth motion.

11. The method of claim 10 further comprising:

determining the frequency and phase of the first motion;

determining the frequency and phase of the second motion; and

determining the frequency and phase of the third motion;

determining the frequency and phase of the fourth motion; and

comparing at least one of the frequency and phase of the first motion and the second motion; and

comparing at least one of the frequency and phase of the third motion and the fourth motion.

12. The method of claim 11 further comprising providing an output signal that is based on at least one of (1) a comparison of the first motion and the second motion and (2) a comparison of the third motion and the fourth motion.

13. An apparatus comprising:

a first cantilever beam comprising a first mass, a first attachment point, and a first cantilever orientation, wherein the first mass has a first center of mass that is coplanar with a first plane, and wherein the first attachment point is coplanar with a second plane, and wherein the first cantilever orientation forms a first angle with a first direction that is aligned with a first axis that is orthogonal to a second axis, and further wherein the first angle is between 90 degrees and 270 degrees;

a second cantilever beam comprising a second mass, a second attachment point, and a second cantilever orientation, wherein the second mass has a second center of mass that is coplanar with the first plane, and wherein the second attachment point is coplanar with the second plane, and further wherein the second cantilever orientation and the first direction form a second angle that is between −

90 degrees and 90 degrees;

a first sensor for sensing motion of the first mass along a second direction that is aligned with the second axis; and

a second sensor for sensing motion of the second mass along the second direction;

wherein the first plane is orthogonal to the second axis;

wherein the second plane is orthogonal to the second axis; and

wherein the first plane and the second plane are displaced on the second axis.

14. The apparatus of claim 13 wherein the first angle is equal to 180 degrees and the second angle is equal to zero degrees.

15. The apparatus of claim 13 further comprising a first linear actuator for inducing a first periodic motion of the first mass and second mass along the second direction.

16. The apparatus of claim 13 further comprising:

a third cantilever beam comprising a third mass, a third attachment point, and a third cantilever orientation, wherein the third mass has a third center of mass that is coplanar with the first plane, and wherein the third attachment point is coplanar with the second plane, and wherein the third cantilever orientation forms a third angle with a third direction that is aligned with a third axis, and wherein the third angle is between 90 degrees and 270 degrees, and further wherein the first axis, second axis, and third axis are mutually orthogonal;

a fourth cantilever beam comprising a fourth mass, a fourth attachment point, and a fourth cantilever orientation, wherein the fourth center of mass is coplanar with the first plane, and wherein the fourth attachment point is coplanar with the second plane, and further wherein the fourth cantilever orientation and the third direction form a fourth angle that is between −

90 degrees and 90 degrees;

a third sensor for sensing motion of the third mass along the second direction; and

a fourth sensor for sensing motion of the fourth mass along the second direction.

17. The apparatus of claim 16 further comprising a first linear actuator for inducing a first periodic motion of the first mass, second mass, third mass, and fourth mass along the second direction.

18. The apparatus of claim 17 further comprising a second linear actuator for inducing a second periodic motion of the first mass, second mass, third mass, and fourth mass along a fourth direction that is orthogonal to the second axis.

19. The apparatus of claim 18 wherein the fourth direction is aligned with one of the first axis and the third axis.

20. An apparatus comprising:

a first cantilever beam comprising a first mass, wherein the first cantilever beam has a first cantilever orientation that is substantially aligned with a first axis, and wherein the first cantilever beam comprises a first physical adaptation for enabling a first acceleration that is aligned with the first axis to induce a first force on the first mass, and wherein the first force is directed positively in a second direction that is substantially aligned with a second axis that is orthogonal to the first axis;

a second cantilever beam comprising a second mass, wherein the second cantilever beam has a second cantilever orientation that is substantially aligned with the first axis, and wherein the second cantilever beam comprises a second physical adaptation for enabling the first acceleration to induce a second force on the second mass, and wherein the second force is directed negatively in the second direction;

a first sensor for sensing a first motion of the first mass, wherein the first motion is directed along the second direction; and

a second sensor for sensing a second motion of the second mass, wherein the second motion is directed along the second direction.

21. The apparatus of claim 20 further comprising:

a first linear actuator for inducing a first periodic motion of the first mass and the second mass along the second direction.

22. The apparatus of claim 20 further comprising:

a third cantilever beam comprising a third mass, wherein the third cantilever beam has a third cantilever orientation that is substantially aligned with a third axis, and wherein the third cantilever beam comprises a third physical adaptation for enabling a second acceleration that is aligned with the third axis to induce a third force on the third mass, and wherein the third force is directed positively in the second direction;

a fourth cantilever beam comprising a fourth mass, wherein the fourth cantilever beam has a fourth cantilever orientation that is substantially aligned with the third axis, and wherein the fourth cantilever beam comprises a fourth physical adaptation for enabling the second acceleration to induce a fourth force on the fourth mass, and wherein the fourth force is directed negatively in the second direction;

a third sensor for sensing motion of the third mass, wherein the third motion is directed along the second direction; and

a fourth sensor for sensing motion of the fourth mass, wherein the fourth motion is directed along the second direction.

23. The apparatus of claim 22 further comprising:

a first linear actuator for inducing a first periodic motion of the first mass, second mass, third mass and fourth mass along the second direction; and

a processor for providing at least one of;

(a) a first signal based on a comparison of the first motion and the second motion;

(b) a second signal based on a comparison of the third motion and the fourth motion;

(c) a third signal based on a comparison of the first motion and the third motion;

(d) a fourth signal based on a comparison of the first motion and the fourth motion;

(e) a fifth signal based on a comparison of the second motion and the third motion; and

(f) a sixth signal based on a comparison of the second motion and the fourth motion.

24. The apparatus of claim 23 further comprising:

a second linear actuator for inducing a second periodic motion of the first mass and the second mass along a direction that is substantially orthogonal to the second axis.

25. The apparatus of claim 20:

wherein the first cantilever has a first stiffness in a first plane that is orthogonal to the second direction and a second stiffness along the second direction, and wherein the first stiffness is higher than the second stiffness; and

wherein the second cantilever has a third stiffness in a second plane that is orthogonal to the second direction and a fourth stiffness along the second direction, and wherein the third stiffness is higher than the fourth stiffness.