SERVO COMPENSATING ACCELEROMETER

Abstract

A servo compensating accelerometer includes a top housing half and a bottom housing half rigidly connected together, and each having coaxial threaded openings. A sensing element is positioned between the top and bottom halves and affixed to the bottom half. Top and bottom magnetic systems, each of which has a magnetic conductor, a permanent magnet and a field concentrator, the magnetic systems being mounted within the respective top and bottom halves of the housing using the threaded openings. A momentum sensor includes the top and bottom magnetic systems, and also includes two movable coils mounted on a plate and positioned within the magnetic systems. A differential angle sensor includes toroidal excitation coils located on the permanent magnets, the magnetic systems and the coils of the momentum sensor. Zero bias of the accelerometer's angular displacement sensor is tuned by adjusting the position of the magnetic systems by moving them in the threaded openings. Stop screws can be used to fix position of the magnetic systems relative to the top and bottom halves of the housing. Two perpendicular mounting surfaces are located on the bottom half of the housing. An electrical circuit that includes a preamplifier, a demodulator, a correcting element, a high frequency generator, an amplifier, the excitation coils and the movable coils, which collectively form a feedback circuit, and generate an output of the accelerometer using an inductor, a resistor, a capacitor and a filter. The sensing element, in one embodiment, can be metallic.

Description

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings:

FIG. 1 illustrates a cross sectional view of one embodiment of the accelerometer of the present invention.

FIG. 2 illustrates a cross sectional view in the direction of the arrow E in FIG. 1.

FIGS. 3A and 3B illustrate the construction of the sensing element of the accelerometer of one embodiment of the present invention.

FIG. 4 illustrates a cross section along the line G-G of FIG. 2.

FIG. 5 illustrates a view along the arrow C in FIG. 1, which shows a base mounting surface A of the accelerometer.

FIG. 6 illustrates a view in the direction of the arrow D in FIG. 1, which shows a base mounting surface B of the accelerometer.

FIG. 7 illustrates an exemplary electrical schematic of the accelerometer of FIG. 1.

FIG. 8 illustrates a structural schematic of mechanical tuning of the zero bias drift of the angular displacement sensor.

FIGS. 9A and 9B illustrate the principle of kinematic tuning of the zero bias drift of the angular displacement sensor.

Claims

1. A servo compensating accelerometer comprising: a housing that includes a top half and a bottom half, each half having an opening;top and bottom magnetic systems within the housing, the magnetic systems adjustably positioned in the openings, wherein each magnetic system includes a magnetic conductor, a magnet and a field concentrator;two movable coils mounted on a movable plate and magnetically coupled to the respective magnetic systems, the movable coils and the magnetic systems forming a momentum sensor;two toroidal excitation coils located on the respective magnets that, together with the magnetic systems and the movable coils, form a differential angular displacement sensor; anda feedback electrical circuit that generates an output signal based on an output of the momentum sensor and which is proportional to applied acceleration and provides a feedback signal to the movable coils to return the movable plate and the movable coils to a neutral position.

2. The accelerometer of claim 1, wherein the two openings are coaxial.

3. The accelerometer of claim 1, wherein the two openings are threaded.

4. The accelerometer of claim 3, wherein the magnetic systems are movable along the threaded openings.

5. The accelerometer of claim 4, wherein a zero bias of the differential angular displacement sensor is tuned by adjusting a position of the magnetic systems by moving magnetic systems using the threaded openings.

6. The accelerometer of claim 1, wherein the magnetic systems are fixed using stop screws.

7. The accelerometer of claim 1, wherein the magnets are permanent magnets.

8. The accelerometer of claim 1, further comprising two perpendicular mounting surfaces located on the bottom half of the housing.

9. The accelerometer of claim 1, wherein a proof mass is formed by the movable plate and the two coils of the momentum sensor.

10. The accelerometer of claim 1, wherein the differential angular displacement sensor includes the toroidal excitation coils located on the respective magnets of the magnetic systems and the coils of the momentum sensor located on a plate, and wherein the momentum sensor coils provide the output signal of the accelerometer.

11. A servo compensating accelerometer comprising: a housing having two opposing openings;a momentum sensor formed by two movable coils and two magnetic systems, wherein the two movable coils are affixed to a movable plate and positioned in gaps of the magnetic systems, and wherein each magnetic system includes a magnetic conductor, a magnet and a field concentrator;a differential angular displacement sensor formed by two toroidal excitation coils located on the respective magnets, the magnetic systems and the movable coils; andan electrical circuit that generates an output signal based on an output of the momentum sensor and which is proportional to applied acceleration and provides a signal to the momentum sensor to return the movable plate and the movable coils to a neutral position.

12. The accelerometer of claim 11, wherein the two openings are coaxial.

13. The accelerometer of claim 11, wherein the two openings are threaded.

14. The accelerometer of claim 13, wherein the magnetic systems are movable along the threaded openings.

15. The accelerometer of claim 14, wherein a zero bias of the differential angular displacement sensor is tuned by adjusting a position of the magnetic systems by moving magnetic systems using the threaded openings.

16. The accelerometer of claim 1, wherein the magnetic systems are fixed using stop screws.

17. The accelerometer of claim 11, wherein the magnets are permanent magnets.

18. The accelerometer of claim 11, further comprising two perpendicular mounting surfaces located on the bottom half of the housing.

19. The accelerometer of claim 11, wherein a proof mass is formed by the movable plate and the two coils of the momentum sensor.

20. The accelerometer of claim 11, wherein the differential angular displacement sensor includes the toroidal excitation coils located on the respective magnets of the magnetic systems and the coils of the momentum sensor located on a plate, and wherein the momentum sensor coils provide the output signal of the angular displacement sensor.