Gravity gradiometer compass

• US 4,399,694 A
• Filed: 12/04/1980
• Issued: 08/23/1983
• Est. Priority Date: 12/04/1980
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Sperry Corporation
• Inventors: Mayer, Arthur
• Primary Examiner(s): Gill, James J.
• Application Number:
  US06/213,137
• Time in Patent Office: 992 Days
• Field of Search: 33/318, 33/324, 33/326, 73/178 R, 73/382 G
• US Class Current: 73/178.00R
• CPC Class Codes: G01C 17/00 Compasses; Devices for ascertaining true or magnetic north for navigation or surveying purposes using gyroscopic effect G01C19/00
• CPC Class Codes: G01V 7/16 specially adapted for use on moving platforms, e.g. ship, aircraft

Abstract

A gravity gradiometer disposed upon a gyroscopically stabilized platform in a vehicle can be modified, without impairment of its normal operation, to perform compassing functions.

Claims

1. In a vehicular mounted gravity gradiometer system of the type having a gravity gradiometer which is disposed upon a gyroscopically stabilized platform and which is slewed through an angle α

in response to a modified signal of an azimuth rate modulator means, a compass comprising;

(a) means for resolving the output of said gradiometer into at least the gradient Γ

_ED ;

(b) means for synchronously demodulating the gradient Γ

_ED, to develop a signal proportional to Δ

Γ

_ED ;

(c) means for summing Δ

Γ

_ED with the output of said azimuth rate modulator means to produce the modified slewing signal;

(d) means for integrating the output of said azimuth rate modulator to determine α

;

(e) means for indicating the angular rotation of said stabilized platform relative to the vehicle; and

(f) means for summing the output of said integrating means with the output of said angular rotation indicating means to provide a vehicular heading.

2. An apparatus according to claim 1 wherein said means for demodulating the gradient Γ

_ED includes an accumulator that alternately adds and subtracts the current values of Γ

_ED.

3. An apparatus according to claim 2 wherein said azimuth rate modulator means includes a pulse generator.

4. An apparatus according to claim 3 wherein said means for resolving the output of said gradiometer includes a resolver.

5. An apparatus according to claim 4 wherein said means for indicating angular rotation includes a synchro.

6. An apparatus according to claim 4 wherein said means for indicating angular rotation includes a shaft position encoder.