Gravity Gradiometer Direct Higher-Order Tensor Extraction
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Solution Overview
Problem
Current gravity gradiometers are unable to directly measure third, fourth, or higher-order gravity tensor components, relying on costly and time-consuming calibration procedures for navigation and resource exploration, which introduces noise and clutter in low-order signal data.
Innovation Solution
A gradiometer instrument with a group of equiangularly spaced accelerometers, where the second, third, and fourth-order gravity tensor components are extracted by processing the outputs of the accelerometers at specific multiples of the spin rate, allowing for direct measurement and subtraction of higher-order 'noise' from low-order signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration procedures are used to measure gravity tensor components, then navigation and resource exploration can be performed, but the process is costly and time-consuming, introducing noise and clutter in low-order signal data
Solution Approach 1:
The patent extracts higher-order tensor components from the accelerometer signals and removes them as separate entities. By isolating these higher-order components and subtracting them from the total signal, the system eliminates noise and clutter from low-order measurements without requiring time-consuming calibration procedures
Solution Approach 2:
The patent changes the measurement parameters by directly measuring higher-order gravity tensor components (third, fourth, and higher-order) in addition to the traditional second-order components. This parameter expansion allows the system to identify and remove noise sources systematically, improving measurement precision while reducing calibration time
2Measurement precision
If calibration procedures are used to measure gravity tensor components, then navigation and resource exploration can be performed, but the cost is high
Solution Approach 1:
The system performs self-calibration by automatically measuring and processing higher-order tensor components to remove noise from low-order signals. The gradiometer instrument independently identifies and eliminates measurement errors without requiring external calibration equipment or procedures, reducing both cost and time
Solution Approach 2:
The patent extracts higher-order tensor components from the accelerometer signals and removes them as separate entities. By isolating these higher-order components and subtracting them from the total signal, the system eliminates noise and clutter from low-order measurements without requiring costly calibration procedures
3Measurement precision
If higher-order tensor components are directly measured, then noise and clutter can be removed from low-order signals, but the device complexity increases
Solution Approach 1:
The patent segments the gravity tensor measurement into distinct order components (second-order, third-order, fourth-order, etc.). By processing each order separately through dedicated signal processing channels, the system manages complexity through modular organization while achieving high measurement precision
Solution Approach 2:
The same set of accelerometers serves multiple functions: measuring second-order tensor components for traditional gravity gradient measurement and simultaneously measuring third, fourth, and higher-order components for noise removal. This multi-functionality reduces the need for additional specialized equipment
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the direct measurement and removal of higher-order tensor components, reducing the need for costly calibration procedures and enhancing the accuracy of low-order signal data by eliminating noise, thereby improving navigation and resource exploration efficiency.
Implementation Method 1
each accelerometer experiences the same acceleration forces as it proceeds along its orbital path. However, when the local gravity field is perturbed by the presence of one or more masses and/or the spin axis is tilted relative to the local vertical field lines, each accelerometer will experience different accelerations throughout its respective orbit about the spin axis
Data Source
AI summary
An instrument for determining the second and/or third-order components of the gravity tensor includes a group of six accelerometers arranged at an equal radius from a spin axis and positioned at 60 degree intervals about the spin axis with the sensing axis of each accelerometer aligned tangentially to the circle subscribed by the accelerometers as they rotate about the spin axis. A gyro-stabilized platform maintains the accelerometer arrangement at a preferred alignment relative to the local gravity vector. As the accelerometers orbit about the spin axis, each accelerometer outputs a sinusoidal signal that is offset by 60 degrees from its immediately adjacent leading and trailing accelerometers with the outputs thereof processed to provide the second-order component and the third-order tensor component. In another arrangement, a group of eight accelerometers arranged at an equal radius from a spin axis and positioned at 45 degree intervals about the spin axis can provide second, third, and fourth-order tensor components. The higher-order tensor components are of use in “de-cluttering” the lower-order tensor components.