Pendulous oscillating gyroscopic accelerometer

• US 5,691,470 A
• Filed: 10/16/1995
• Issued: 11/25/1997
• Est. Priority Date: 08/03/1993
• Status: Expired due to Term

• Current Assignee: Milli Sensor Systems & Actuators, Inc.
• Original Assignee: Milli Sensor Systems & Actuators, Inc.
• Inventors: Cardarelli, Donato, Sapuppo, Michele S.
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): Kwok, Helen C.
• Application Number:
  US08/543,776
• Time in Patent Office: 771 Days
• Field of Search: 73/503.3, 73/504.02, 73/504.03, 73/504.09, 73/504.12, 73/504.18, 73/570, 73/571, 73/514.01, 73/514.02, 74/5 R, 74/5.34
• US Class Current: 73/504.02
• CPC Class Codes: G01C 19/42 for indicating rate of turn; for integrating rate of turn
• CPC Class Codes: G01P 15/13 by measuring the force required to restore a proofmass subjected to inertial forces to a null position
• CPC Class Codes: G01P 15/14 by making use of gyroscopes gyroscopes per se G01C19/00

Abstract

A pendulous oscillating gyroscopic accelerometer, comprising: a fixed case; a servo driven member mounted to the case for oscillation about a servo axis; a torque summing member mounted to the servo driven member for rotation about an output axis transverse to the servo axis; a rotor driven member mounted to the torque summing member for oscillation about a reference axis transverse to both the output axis and the servo axis; a pendulosity carried by at least one of the torque summing member and the rotor driven member to create a mass imbalance about an output axis; a first oscillation device for oscillating the rotor driven member about the reference axis, the oscillation having a first amplitude, a first frequency and a first phase; a second oscillation device for oscillating the servo driven member about the servo axis, the oscillation having a second amplitude, a second frequency and a second phase; a measurement device for determining the rotation of the torque summing member about the output axis resulting from pendulosity torque caused by acceleration of the pendulosity; a controller, responsive to the measurement device, for altering the oscillation caused by at least one of the oscillation devices to create torque to counterbalance pendulosity torque; and a determinator, responsive to the controller, for determining acceleration along the input axis.

Claims

1. A pendulous oscillating gyroscopic accelerometer having an accelerometer input axis, comprising:

a fixed case;

a servo driven member mounted to said case for sinusoidal oscillation about a servo axis;

a torque summing member mounted to said servo driven member to allow rotational motion about an output axis transverse to said servo axis;

a rotor driven member mounted to said torque summing member for sinusoidal oscillation about a reference axis transverse to both said output axis and said servo axis;

a pendulosity carried by at least one of said torque summing member and said rotor driven member to create a mass imbalance about said output axis in which pendulosity torque due to acceleration along the accelerometer input axis causes a DC rotation of said torque summing member about said output axis;

first oscillation means for sinusoidally oscillating said rotor driven member about said reference axis, the oscillation having a first amplitude, a first frequency and a first phase;

second oscillation means for sinusoidally oscillating said servo driven member about said servo axis, the oscillation having a second amplitude, a second frequency and a second phase;

wherein the oscillations of said rotor driven member and of said servo driven member create a gyroscopic torque, which causes DC rotation of said torque summing member about said output axis;

measurement means for determining the rotational motion of said torque summing member about said output axis;

control means, responsive to said measurement means, for altering the oscillation of at least one of said first and second oscillation means to create a change in said gyroscopic torque to counterbalance pendulosity torque; and

means, responsive to said control means, for determining acceleration of said accelerometer along said input axis.

2. The pendulous oscillating gyroscopic accelerometer of claim 1 in which said first frequency and said second frequency are the same.

3. The pendulous oscillating gyroscopic accelerometer of claim 2 in which the phase difference between the oscillations of said rotor driven member and of said servo driven member is constant.

4. The pendulous oscillating gyroscopic accelerometer of claim 3 in which said control means alters at least one of said first and second amplitudes.

5. The pendulous oscillating gyroscopic accelerometer of claim 2 in which said control means alters the phase difference between the first phase and the second phase.

6. The pendulous oscillating gyroscopic accelerometer of claim 2 in which said control means alters both said first and second frequencies together.

7. The pendulous oscillating gyroscopic accelerometer of claim 6 in which said control means maintains said first and second amplitudes constant.

8. The pendulous oscillating gyroscopic accelerometer of claim 6 in which said control means maintains the phase difference between the first phase and the second phase constant.

9. The pendulous oscillating gyroscopic accelerometer of claim 1 in which said first oscillation means oscillates said rotor driven member at resonance.

10. The pendulous oscillating gyroscopic accelerometer of claim 1 in which said second oscillation means oscillates said servo driven member at resonance.

11. The pendulous oscillating gyroscopic accelerometer of claim 1 in which said first oscillation means oscillates said rotor driven member at resonance, and said second oscillation means oscillates said servo driven member at resonance.

12. The pendulous oscillating gyroscopic accelerometer of claim 1 in which said first and said second oscillation means are both electromagnetic drives.

13. The pendulous oscillating gyroscopic accelerometer of claim 1 in which said first oscillation means is an electromagnetic drive and said second oscillation means is an electrostatic drive.

14. The pendulous oscillating gyroscopic accelerometer of claim 1 further including means for determining the oscillation of said rotor driven member about said reference axis.

15. The pendulous oscillating gyroscopic accelerometer of claim 1 in which said first oscillation means is an electrostatic drive and said second oscillation means is an electromagnetic drive.

16. The pendulous oscillating gyroscopic accelerometer of claim 1 in which said first and said second oscillation means are both electrostatic drives.

17. The pendulous oscillating gyroscopic accelerometer of claim 1 in which said measurement means includes a non-contact measurement device.

18. The pendulous oscillating gyroscopic accelerometer of claim 17 in which said measurement device is capacitive.

19. The pendulous oscillating gyroscopic accelerometer of claim 17 in which said measurement device is electromagnetic.

20. The pendulous oscillating gyroscopic accelerometer of claim 17 in which said measurement device is optical.

21. The pendulous oscillating gyroscopic accelerometer of claim 1 further including means for determining the oscillation of said servo driven member about said servo axis.

22. The pendulous oscillating gyroscopic accelerometer of claim 1 in which said rotor driven member is a generally planar member mounted by a plurality of spaced flexures to said torque summing member, and the reference axis is normal to the rotor driven member, whereby the oscillation of said rotor driven member is within the plane of said rotor driven member.

23. The pendulous oscillating gyroscopic accelerometer of claim 22 in which said torque summing member is a generally planar member surrounding said rotor driven member, and is pivotably mounted to said servo driven member to pivot about the output axis.

24. The pendulous oscillating gyroscopic accelerometer of claim 23 in which said servo driven member is a generally planar member surrounding said torque summing member and is pivotably mounted to said case to pivot about the servo axis.

25. The pendulous oscillating gyroscopic accelerometer of claim 1 in which said rotor driven member is pivotably mounted within said torque summing member, to pivot about the reference axis.

26. The pendulous oscillating gyroscopic accelerometer of claim 25 in which said torque summing member is a generally planar member and is mounted by a plurality of spaced flexures to said servo driven member, and the output axis is normal to the torque summing member, whereby the torque summing member pivots within its plane about the output axis.

27. The pendulous oscillating gyroscopic accelerometer of claim 26 in which said servo driven member is a generally planar member surrounding said torque summing member, and is pivotably mounted to said case to pivot about the servo axis.

28. The pendulous oscillating gyroscopic accelerometer of claim 1 in which said rotor driven member is pivotably mounted within said torque summing member, to pivot about the reference axis.

29. The pendulous oscillating gyroscopic accelerometer of claim 28 in which said torque summing member is pivotably mounted to said servo driven member, to pivot about the output axis.

30. The pendulous oscillating gyroscopic accelerometer of claim 29 in which said servo driven member is a generally planar member and is mounted by a plurality of spaced flexures to said case, whereby said servo driven member pivots within its plane.

31. A pendulous oscillating gyroscopic accelerometer having an accelerometer input axis, comprising:

a fixed case;

a generally planar servo driven member mounted to said case for sinusoidal oscillation within the plane of said servo driven member and about an accelerometer servo axis;

a generally planar torque summing member mounted to said servo driven member to allow rotational motion about an output axis transverse to said servo axis;

a generally planar rotor driven member mounted to said torque summing member for sinusoidal oscillation about a reference axis transverse to both said output axis and said servo axis;

a pendulosity carried by at least one of said torque summing member and said rotor driven member to create a mass imbalance about the output axis, in which pendulosity torque due to acceleration along the accelerometer input axis causes a DC rotation of said torque summing member about said output axis;

first oscillation means for sinusoidally oscillating said rotor driven member about said reference axis, the oscillation having a first amplitude, a first frequency and a first phase;

second oscillation means for sinusoidally oscillating said servo driven member about said servo axis, the oscillation having a second amplitude, a second frequency and a second phase;

wherein the oscillations of said rotor driven member and of said servo driven member create gyroscopic torque, which causes DC rotation of said torque summing member about said output axis;

measurement means for determining the rotational motion of said torque summing member about said output axis;

control means, responsive to said measurement means, for altering the oscillation of at least one of said first and second oscillation means to create a change in said gyroscopic torque to counterbalance pendulosity torque; and

means, responsive to said control means, for determining acceleration of said accelerometer along said accelerometer input axis.

32. A pendulous oscillating gyroscopic accelerometer having an accelerometer input axis, comprising:

a fixed case;

a generally planar servo driven member mounted to said case for sinusoidal oscillation about an accelerometer servo axis;

a generally planar torque summing member mounted to said servo driven member to allow rotational motion within the plane of said torque summing member and about an output axis transverse to said servo axis;

a generally planar rotor driven member mounted to said torque summing member for sinusoidal oscillation about a reference axis transverse to both said output axis and said servo axis;

a pendulosity carried by at least one of said torque summing member and said rotor driven member to create a mass imbalance about the output axis, in which pendulosity torque due to acceleration along the accelerometer input axis causes a DC rotation of said torque summing member about said output axis;

first oscillation means for sinusoidally oscillating said rotor driven member about said reference axis, the oscillation having a first amplitude, a first frequency and a first phase;

second oscillation means for sinusoidally oscillating said servo driven member about said servo axis, the oscillation having a second amplitude, a second frequency and a second phase;

wherein the oscillations of said rotor driven member and of said servo driven member create gyroscopic torque, which causes DC rotation of said torque summing member about said output axis;

measurement means for determining the rotational motion of said torque summing member about said output axis;

control means, responsive to said measurement means, for altering the oscillation of at least one of said first and second oscillation means to create a change in said gyroscopic torque to counterbalance pendulosity torque; and

means, responsive to said control means, for determining acceleration of said accelerometer along said accelerometer input axis.

33. A pendulous oscillating gyroscopic accelerometer having an accelerometer input axis, comprising:

a fixed case;

a generally planar servo driven member mounted to said case for sinusoidal oscillation about an accelerometer servo axis;

a generally planar torque summing member mounted to said servo driven member to allow rotational motion about an output axis transverse to said servo axis;

a generally planar rotor driven member mounted to said torque summing member for sinusoidal oscillation within the plane of said rotor driven member and about a reference axis transverse to both said output axis and said servo axis;

a pendulosity carried by at least one of said torque summing member and said rotor driven member to cream a mass imbalance about the output axis, in which pendulosity torque due to acceleration along the accelerometer input axis causes a DC rotation of said torque summing member about said output axis;

first oscillation means for sinusoidally oscillating said rotor driven member about said reference axis, the oscillation having a first amplitude, a first frequency and a first phase;

second oscillation means for sinusoidally oscillating said servo driven member about said servo axis, the oscillation having a second amplitude, a second frequency and a second phase;

wherein the oscillations of said rotor driven member and of said servo driven member create gyroscopic torque, which causes DC rotation of said torque summing member about said output axis;

measurement means for determining the rotational motion of said torque summing member about said output axis;

control means, responsive to said measurement means, for altering the oscillation of at least one of said first and second oscillation means to create a change in said gyroscopic torque to counterbalance pendulosity torque; and

means, responsive to said control means, for determining acceleration of said accelerometer along said accelerometer input axis.