Gravity Gradiometer Bias Correction via Multi-Orientation Measurement
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Solution Overview
Problem
Existing gravity gradiometers face challenges in achieving accurate and repeatable measurements due to bias errors, particularly constant and drifting biases, which affect the accuracy and repeatability of geophysical surveys by introducing variations in underground density distribution estimates.
Innovation Solution
A method and apparatus for determining bias-corrected values of gravity gradient tensor components using a gravity gradiometer that takes multiple measurements in different orientations over time, allowing for the identification and compensation of constant and time-varying biases, thereby improving measurement accuracy and repeatability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a gravity gradiometer takes multiple measurements in different orientations over time, then measurement accuracy and repeatability are improved, but device complexity and measurement time increase
Solution Approach 1:
The patent applies preliminary action by performing measurements in multiple predetermined orientations according to a specific measurement pattern. The measurement pattern is designed in advance to systematically capture gravity gradient components while accounting for bias errors, allowing the system to achieve high accuracy without requiring complex real-time processing or additional hardware.
Solution Approach 2:
The patent segments the measurement process into discrete orientation steps, where the gravity gradiometer measures components at specific orientations (e.g., 0°, 45°, 90°, 135°) according to a measurement pattern. This segmentation allows systematic collection of data needed to separate true gravity gradient signals from bias errors through mathematical processing.
2Measurement precision
If a gravity gradiometer takes multiple measurements in different orientations over time, then measurement accuracy and repeatability are improved, but measurement time increases
Solution Approach 1:
The patent employs periodic action by implementing a systematic measurement pattern that cycles through different orientations in a predetermined sequence. This periodic measurement approach ensures that bias errors are captured consistently across different orientations and time points, enabling accurate separation of bias from true gravity gradient signals through mathematical processing.
3Measurement precision
If bias errors are compensated through multiple measurements and processing, then measurement accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent applies feedback by using the collected measurement data from multiple orientations to compute bias error estimates, which are then used to correct the gravity gradient measurements. The measurement pattern is designed to provide sufficient information for calculating bias terms, and these bias corrections are fed back into the measurement process to improve overall accuracy.
Data Source
AI summary
Systems and methods for determining a bias-corrected value of at least one component of a gravity gradient tensor using a gravity gradiometer and a measurement bias of the gravity gradiometer wherein the measurement bias varies with time, by taking at least three measurements with the gravity gradiometer positioned in at least two orientations. Any gravity gradiometer can be used, including a Cross-Component Gravity Gradiometer (CCGG), an Orthogonal Quadrupole Responder (OQR), an In-Line Responder (ILR), a Diagonal-Component Gravity Gradiometer, or a Multi-Component Gravity Gradiometer (MCGG).