Inertial navigation device for ion propulsion driven spacecraft

• US 20040244486A1
• Filed: 05/07/2004
• Published: 12/09/2004
• Est. Priority Date: 06/05/2003
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Berstis, Vicktors
• Granted Patent: US 6,898,970 B2
• Time in Patent Office: Days
• US Class Current: 73/514.31
• CPC Class Codes: G01V 7/02 Details

Abstract

An extremely sensitive accelerometer suitable for use in extreme temperatures such as those encountered during space travel is formed by levitating a magnet in a box or sphere composed of diamagnetic material such as pyrolytic carbon, and a means for measuring the position of the magnet within the enclosure is provided so that over time, the position of the magnet can be monitored. Knowing the mass of the suspended magnet, the displacement over time of the magnetic can be used to calculate acceleration, which can then be used to determine position of a space vehicle.

Claims

1. An apparatus for very sensitive measurement of acceleration and changes in inertia in a low-gravity, low-magnetic field environment, suitable for use in a wide temperature range, said apparatus comprising:

an enclosure defining a cavity, said enclosure being comprised of a diamagnetic material;

a mass disposed in said cavity such that it is subject to diamagnetic forces from said enclosure, said mass being comprised of a magnetic material and assuming a quiescent position when not undergoing acceleration or changes in inertia; and

at least one mass displacement detector configured to detect movement of said mass from said quiescent position during periods of acceleration or changes in inertia, said mass displacement detector providing an output relative to the instantaneous amount of displacement of the mass in at least one axis.

2. The apparatus as set forth in claim 1 wherein said diamagnetic material is selected from the group of diamagnetic carbon, graphic, pyrolytic graphite, and Bismuth.

3. The apparatus as set forth in claim 1 wherein said enclosure is approximately spherical in shape.

4. The apparatus as set forth in claim 1 wherein said enclosure is approximately polyhedral in shape.

5. The apparatus as set forth in claim 1 wherein said mass displacement detector comprises a laser emitter fitted with a defractor, and one or more sensors adapted to detect impending light of the frequency emitted by said laser emitter.

6. The apparatus as set forth in claim 1 wherein said mass displacement detector comprises at least one Hall-effect sensor.

7. The apparatus as set forth in claim 1 wherein said mass displacement detector comprises a phase interferometer.

8. The apparatus as set forth in claim 1 wherein said mass displacement detector comprises at least two detectors configured to measure displacement of said mass along three or more separate axes.

9. The apparatus as set forth in claim 8 wherein said three axes are orthogonally related to each other.

10. The apparatus as set forth in claim 1 further comprising:

one or more acceleration calculators configured to receive said displacement detector output, and to determine an amount of acceleration in at least one axis based upon a known mass value of said mass; and

an acceleration value output for outputting said calculated axial acceleration magnitude.

11. The apparatus as set forth in claim 10 wherein said calculators comprise at least two calculators, each of which is configured to determine an acceleration value in one of three independent axes, and wherein said output is configured to output multi-dimensional acceleration values.

12. The apparatus as set forth in claim 11 wherein said independent axes are orthogonally related to each other.

13. The apparatus as set forth in claim 11 wherein said output is configured to output two or more vectors of acceleration value in a rectangular vector format.

14. The apparatus as set forth in claim 11 wherein said output is configured to output two or more vectors of acceleration value in a polar representation.

15. The apparatus as set forth in claim 10 further comprising:

a time reference; and

a navigational processor configured to receive said acceleration value output(s) and a time value from said time reference, and configured to determine a net displacement of a vehicle with reference to an initial velocity and initial position.

16. An apparatus for very sensitive measurement of acceleration and changes in inertia in a low-gravity, low-magnetic field environment, suitable for use in a wide temperature range, said apparatus comprising:

an enclosure defining a cavity, said enclosure being comprised of a magnetic material;

a mass having disposed in said cavity such that it is subject to magnetic forces from said enclosure, said mass being comprised of a diamagnetic material and assuming a quiescent position when not undergoing acceleration or changes in inertia; and

at least one mass displacement detector configured to detect movement of said mass from said quiescent position during periods of acceleration or changes in inertia, said mass displacement detector providing an output relative to the instantaneous amount of displacement of the mass in at least one axis.

17. The apparatus as set forth in claim 16 wherein said diamagnetic material is selected from the group of diamagnetic carbon, graphic, pyrolytic graphite, and Bismuth.

18. The apparatus as set forth in claim 16 wherein said enclosure is approximately spherical in shape.

19. The apparatus as set forth in claim 16 wherein said enclosure is approximately polyhedral in shape.

20. The apparatus as set forth in claim 16 wherein said mass displacement detector comprises a laser emitter fitted with a defractor, and one or more sensors adapted to detect impending light of the frequency emitted by said laser emitter.

21. The apparatus as set forth in claim 16 wherein said mass displacement detector comprises at least one Hall-effect sensor.

22. The apparatus as set forth in claim 16 wherein said mass displacement detector comprises a phase interferometer.

23. The apparatus as set forth in claim 16 wherein said mass displacement detector comprises at least two detectors configured to measure displacement of said mass along three or more separate axes.

24. The apparatus as set forth in claim 23 wherein said three axes are orthogonally related to each other.

25. The apparatus as set forth in claim 16 further comprising:

one or more acceleration calculators configured to receive said displacement detector output, and to determine an amount of acceleration in at least one axis based upon a known mass value of said mass; and

an acceleration value output for outputting said calculated axial acceleration magnitude.

26. The apparatus as set forth in claim 25 wherein said calculators comprise at least two calculators, each of which is configured to determine an acceleration value in one of three independent axes, and wherein said output is configured to output multi-dimensional acceleration values.

27. The apparatus as set forth in claim 26 wherein said independent axes are orthogonally related to each other.

28. The apparatus as set forth in claim 26 wherein said output is configured to output two or more vectors of acceleration value in a rectangular vector format.

29. The apparatus as set forth in claim 26 wherein said output is configured to output two or more vectors of acceleration value in a polar representation.

30. The apparatus as set forth in claim 25 further comprising:

a time reference; and

a navigational processor configured to receive said acceleration value output(s) and a time value from said time reference, and configured to determine a net displacement of a vehicle with reference to an initial velocity and initial position.