Giles M Hofmeyer

US Patent:

53578023, Oct 25, 1994

Filed:

May 7, 1993

Appl. No.:

8/058419

Inventors:

Giles M. Hofmeyer - Niagara Falls NY
Clive A. Affleck - Williamsville NY

Assignee:

Textron, Incorporated - Providence RI

International Classification:

G01M 112

US Classification:

73382G

Abstract:

A gravity gradiometer and method for measurement of changes in the intensity of a gravitational field experienced during traversal over earth's terrain, or past a massive object, has a set of eight accelerometers disposed on rotating disc, or on a pair of parallel discs, and arranged uniformly about a central rotational axis of the disc, or of the pair of discs. Each accelerometer develops a signal for maintaining a pendulum in its position of swing along an input axis of the accelerometer. Each input axis, for all of the accelerometers, is perpendicular or parallel to a radius of a disc. The accelerometers are treated as two groups of four accelerometers wherein, in each group, the accelerometers are disposed in pairs about perpendicular diameters of the disc or the pair of discs. Signal processing is accomplished by adding signals of diametrically opposed accelerometers to obtain sum signals and then, in each group, taking the difference between the sum signals and demodulating the difference at twice the rotational frequency. The results of the two groups of signals are combined to give tensor terms which are free of disc rotation frequency.