Development of airborne gravity gradiometer based on a quartz flexible accelerometer

Abstract

1. Progress in gravity gradiometer development Working principleThe core component of a gravity gradiometer is a gravity gradient sensor. The gravity gradient sensor developed by Tianjin Institute of Navigation Instruments adopts a differential measurement technique of rotating accelerometer to realize a common mode suppression of motion acceleration and differential extraction of a gravity gradient signal. The main body of the sensor is a rigid platform with four symmetrically mounted low noise and high resolution accelerometers (a1, a2, a3, a4). Four accelerometers are at the same distance from the center of the device. The input axis is perpendicular to the central rotation axis along the tangent direction of the platform plane. The two pairs of accelerometers are perpendicular to each other. Two independent gravity gradient tensors in the plane of the platform can be measured when the device rotates around a fixed rotation axis. The sum of the outputs (a1 + a2) and (a3 + a4) of a pair of accelerometers with relative mounting positions will eliminate the linear acceleration perpendicular to the axis of rotation, and the difference between the outputs of the two pairs of accelerometers [(a1 + a2) -(a3 + a4)] will eliminate the angular acceleration around the axis of rotation, and the gravity gradient signal can be obtained by demodulating the sum and difference of the outputs of the accelerometers. In order to measure the gravity gradient on a moving base, the gravity gradient sensor needs to be placed on an inertial stabilized platform with gyroscopes and accelerometers.

Error analysis of calibration for horizontal tensor rotating accelerometer gravity gradiometer

“…The Tianjin Navigation Instrument Research Institute successfully developed high-resolution quartz flexible accelerometers that were specifically designed for a RAGG with a noise floor of 1 ng/√Hz (1 g ≈ 9.8 m s −2 ) and nearly 10 E/√Hz by converting a RAGG (the baseline radius of the RAGG is 0.3 m). This RAGG achieved a 40 E resolution level [7], and shipborne tests have been attempted [8]. In the development of high-precision accelerometers in other types, Williams et al [9] utilized the diffraction grating principle to create an optical-based accelerometer, this accelerometer achieved a noise floor of 3 ng/√Hz within a bandwidth of 0.1-100 Hz.…”

Experimental analysis of the performance of a new shipboard gravity gradient measurement system

“…The China Aero Geophysical Survey and Remote Sensing Center for Natural Resources, and Tianjin Institute of Nautical Instruments have made significant breakthroughs in various key technologies since the beiginning of the 11th Five-Year Plan in year 2006. The resolution of the quartz flexible accelerometer has been increased from 1 × 10 −5 g to 1 × 10 −9 g [20,21], and China's first self-controllable gravity gradient measurement system (GGMS) for a shipborne mobile platform has been developed and shipborne tested. Here we briefly present this new GGMS, and the results of laboratory and shipboard tests conducted to assess system performance.…”

Integration of Residual Terrain Modelling and the Equivalent Source Layer Method in Gravity Field Synthesis for Airborne Gravity Gradiometer Test Site Determination

“…Many other projects relying on alternative technologies have come into sight, e.g., the Superconducting Gradiometer developed by U.Maryland and by ARKEX company [13], MEMS gravity gradiometer by University of Twente [14], cold-atomic interferometer gravity gradiometer by Stanford University [15], quantum gravity gradiometer by Yale University, Università Degli Studi di Firenze, Observatoire de Paris and Office National d'Etudes et de Researches Aerospatiales (ONERA) [16][17][18][19][20][21]. Additionally, there are projects underway in China for the development of a rotating accelerometer gravity gradiometer and atom interferometry gravity gradiometer, which are expected to be used in aircraft for efficient gravity field detection over mountain and coastal areas [22][23][24][25]. Both of these gradiometers could achieve a 0.25 Hz sampling rate.…”