Flexural pivot for micro-sensors
A micro-sensor is provided with a fixed reference frame and an elastic pivot. The elastic pivot has at least two co-axial segments of pivot and is coupled to the fixed reference frame. The elastic pivot has a neutral axis that is a central line of the pivot. A moveable body is coupled to the elastic pivot and the reference frame. The moveable body and the reference frame share a reference surface. The moveable body extends between the two co-axial segments to provide that for a rotation of the moveable body about the pivot the moveable body approaches the reference surface at a first side, and recedes from the reference surface from an opposite side to provide an opening gap and a closing gap. The neutral axis is below the reference surface. At least a first gauge is configured to detect tilt about the elastic pivot and measure separation of the moveable body and the reference frame at the reference surface. The gauge provides a measurement of the opening and closing of the opening and closing gaps. Inputs to be measured cause the moveable body to rotate about the pivot and strain the gauge.
1. A micro-sensor, comprising:
a fixed reference frame;
an elastic pivot with at least two co-axial segments of pivot and coupled to the fixed reference frame and having a neutral axis that is a central line of the pivot,
a moveable body coupled to the elastic pivot and the reference frame, the moveable body and the reference frame sharing a reference surface, the moveable body extending between the two co-axial segments to provide that for a rotation of the moveable body about the pivot the moveable body approaches the reference surface at a first side and recedes from the reference surface from an opposite side and provide an opening gap and a closing gap, the neutral axis being below the reference surface;
at least a first gauge configured to detect tilt about the elastic pivot and measure separation of the moveable body and the reference frame at the reference surface, the gauge providing a measurement of the opening and closing of the opening and closing gaps; and
wherein inputs to be measured cause the moveable body to rotate about the pivot and strain the gauge.
2. The sensor of claim 1 , wherein the reference surface is coplanar.
3. The sensor of claim 1 , wherein the neutral axis is a line that defines where motion occurs.
4. The sensor of claim 1 , wherein tilting the moveable body positions the reference surface above the pivot into a first sense of strain, that is tension which occurs between the moveable body and the reference frame when the solid body is on a first side of the pivot.
5. The sensor of claim 4 , wherein a second sense of strain that is compression which occurs when the solid body is an opposing second side of the pivot.
6. The sensor of claim 1 , wherein bridges or half-bridges of gauges with equal and opposite strain are created on the reference surface.
7. The sensor of claim 6 , wherein the bridges and half-bridges are electrical bridges and electrical half bridges.
8. The sensor of claim 1 , wherein the sensor is a rotational acceleration sensor.
9. The sensor of claim 8 , wherein the sensor is non-responsive to linear acceleration in response to being balanced on the pivot.
10. The sensor of claim 1 , wherein the sensor is a rotation sensor, wherein rotational accelerations about the neutral axis cause the moveable body to rotate and strain the gauges.
11. The sensor of claim 1 , wherein the moveable body is insensitive to acceleration in the reference plane when a center of the moveable body and the neutral axis are a same distance below the reference surface.
12. The sensor of claim 1 , wherein the sensor is a linear acceleration sensor when the moving body is unbalanced on the pivot.
13. The sensor of claim 1 , wherein the gauge is selected from at least one of, an SOI gauge, a freed gauge, a Teed gauge and interdigitated capacitive gauge.
14. The sensor of claim 1 , wherein a pendulum is coupled to the pivot and tethered to the reference frame by hinges.
15. The sensor of claim 14 , wherein the pendulum is defined when an input to the sensor is away from a center of the pivot.
16. The sensor of claim 15 , wherein the pendulum swings perpendicular upon a hinge, and the pendulum tilts in a plane of the hinge.
17. The sensor of claim 16 , wherein the pendulum tilts about the hinge.
18. The sensor of claim 17 , wherein an expanding and shrinking gap is provided on opening and closing gaps on the pendulum.
19. The sensor of claim 1 , wherein four gauges are provided, each being a single link that are wired to form a closed full bridge.
20. The sensor of claim 19 , further comprising:
a crossover to close the bridge.
21. The sensor of claim 1 , wherein each of a gauge has at least one end on the reference frame.
22. The sensor of claim 1 , wherein a Wheatstone bridge is created when tensile and compressive gauges are at the reference surface.
23. The sensor of claim 1 , wherein the pivot provides opening and closing spaces on the reference surface in response to an out-of plane deflection at a remote point.
24. A force sensor, comprising:
a fixed reference frame;
an elastic pivot with at least two co-axial segments of pivot and coupled to the fixed reference frame and having a neutral axis that is a central line of the pivot,
a moveable body coupled to the elastic pivot and the reference frame, the moveable body and the reference frame sharing a reference surface, the moveable body extending between the two co-axial segments to provide that upon application of a force a rotation of the moveable body about the pivot occurs with the moveable body approaching the reference surface at a first side and receding from the reference surface from an opposite side and provide an opening gap and a closing gap, the neutral axis being below the reference surface;
at least a first gauge configured to detect tilt about the elastic pivot and measure separation of the moveable body and the reference frame at the reference surface, the gauge providing a measurement of the opening and closing of the opening and closing gaps; and
wherein inputs to be measured cause the moveable body to rotate about the pivot and strain the gauge.
25. The sensor of claim 24 , wherein the force is an input that is remote from the pivot and causes compression or tension in the gauge.
26. The sensor of claim 24 , wherein the force is an input away from the neutral axis.
27. The sensor of claim 24 , further comprising:
a counter balance and a long arm at opposite sides of the pivot.
28. A micro-sensor, comprising:
a fixed reference frame;
an elastic pivot with at least two co-axial segments of pivot and coupled to the fixed reference frame and having a neutral axis that is a central line of the pivot,
a moveable body coupled to the elastic pivot and the reference frame, the moveable body and the reference frame sharing a reference surface, the moveable body extending between the two co-axial segments to provide that for a rotation of the moveable body about the pivot the moveable body approaches the reference surface at a first side and recedes from the reference surface from an opposite side and provide an opening gap and a closing gap, the neutral axis being below the reference surface;
at least a first gauge configured to detect tilt about the elastic pivot and measure separation of the moveable body and the reference frame at the reference surface, the gauge providing a measurement of the opening and closing of the opening and closing gaps; and
wherein mass is added or removed from the moveable body to make the moveable body responsive to acceleration forces.
29. A micro-sensor, comprising:
a fixed reference frame;
an elastic pivot with at least two co-axial segments of pivot and coupled to the fixed reference frame and having a neutral axis that is a central line of the pivot,
a moveable body coupled to the elastic pivot and the reference frame, the moveable body and the reference frame sharing a reference surface, the moveable body extending between the two co-axial segments to provide that for a rotation of the moveable body about the pivot the moveable body approaches the reference surface at a first side and recedes from the reference surface from an opposite side and provide an opening gap and a closing gap, the neutral axis being below the reference surface;
at least a first gauge configured to detect tilt about the elastic pivot and measure separation of the moveable body and the reference frame at the reference surface, the gauge providing a measurement of the opening and closing of the opening and closing gaps; and
wherein mass is added to the moveable body to provide acceleration of the moveable body through a plane of the reference surface.
30. A micro-sensor, comprising:
a fixed reference frame;
an elastic pivot with at least two co-axial segments of pivot and coupled to the fixed reference frame and having a neutral axis that is a central line of the pivot,
a moveable body coupled to the elastic pivot and the reference frame, the moveable body and the reference frame sharing a reference surface, the moveable body extending between the two co-axial segments to provide that for a rotation of the moveable body about the pivot the moveable body approaches the reference surface at a first side and recedes from the reference surface from an opposite side and provide an opening gap and a closing gap, the neutral axis being below the reference surface;
at least a first gauge configured to detect tilt about the elastic pivot and measure separation of the moveable body and the reference frame at the reference surface, the gauge providing a measurement of the opening and closing of the opening and closing gaps; and
wherein mass is removed above or below the pivot to make the moveable body responsive to acceleration within a plane of the reference surface.