New Matching Method for Accelerometers in Gravity Gradiometer

Abstract

The gravity gradiometer is widely used in mineral prospecting, including in the exploration of mineral, oil and gas deposits. The mismatch of accelerometers adversely affects the measuring precision of rotating accelerometer-based gravity gradiometers. Several strategies have been investigated to address the imbalance of accelerometers in gradiometers. These strategies, however, complicate gradiometer structures because feedback loops and re-designed accelerometers are needed in these strategies. In this paper, we present a novel matching method, which is based on a new configuration of accelerometers in a gravity gradiometer. In the new configuration, an angle was introduced between the measurement direction of the accelerometer and the spin direction. With the introduced angle, accelerometers could measure the centrifugal acceleration generated by the rotating disc. Matching was realized by updating the scale factors of the accelerometers with the help of centrifugal acceleration. Further simulation computations showed that after adopting the new matching method, signal-to-noise ratio improved from −41 dB to 22 dB. Compared with other matching methods, our method is more flexible and costs less. The matching accuracy of this new method is similar to that of other methods. Our method provides a new idea for matching methods in gravity gradiometer measurement.

Low-Cost Inertial Measurement Unit Calibration With Nonlinear Scale Factors

“…Other methods must rely on precise equipment, such as [20], [21]. Several methods must use instruments designed by themselves, [22], [23]. It is extremely difficult for us to reproduce these devices.…”

A Subnano-g Electrostatic Force-Rebalanced Flexure Accelerometer for Gravity Gradient Instruments

“…Furthermore, two opposite feedback voltages are applied to the two fixed capacitor plates to generate a difference of potential between the proof mass and the fixed plates, in order to restore the proof mass to its null position. Those voltages would contribute to an electrostatic field between the proof mass and the fixed plates, and yield an electrostatic feedback force on the proof mass [ 21 , 22 , 23 , 24 ]: where is the root mean square (RMS) value of the pumping voltage . The first item in Equation (4) is the effective electrostatic feedback force, and hence the output acceleration can be written as …”

Study on Misalignment Angle Compensation during Scale Factor Matching for Two Pairs of Accelerometers in a Gravity Gradient Instrument

“…Because the gravity field of the Earth is extremely weak, accompanied with a variety of noises from the measuring environment, it imposes extremely harsh requirements on gravity gradient measurement technology. Because of the well-known reasons, people often need to develop some new techniques and methods independently to realize gravity gradient measurement, ceaselessly searching advances in sensor systems, new methods, operational efficiency, data processing and interpretation, and so on [ 1 , 6 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ].…”