Gravity gradiometer accelerometers

US5962782A · kind A · utility

Assignee

• The Broken Hill Proprietary Company Limited · AU

Inventors

• Graeme Joseph O'Keefe · Melbourne, AU
• James Beresford Lee · Schaumburg, US
• Robert John Turner · Dhahran, SA
• Gregory John Adams · Newcastle, AU
• Graham Clifford Goodwin · Newcastle, AU

Key dates

• Filing date: Jul 3, 1997
• Grant date: Oct 5, 1999
• Expiry date: Jul 3, 2017

Classification

• Technology area (CPC G): Physics
• CPC primary: G01V7/04
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

This invention concerns improvements to gravity gradient instruments (GGI) and in particular to the accelerometers that are paired within these instruments. Accelerometers have a proof mass suspended by a spring within a magnetic field. An internal feedback loop provides a signal related to movement of the proof mass back through a reaction coil retaining the proof mass in the magnetic field, to maintain the proof mass stationary. An external feedback loop adjusts the accelerometer scale factor. The internal feedback loop provides second order compensation to the proof mass and the spring stiffness. In a further aspect the invention is a method of matching accelerometer pairs.