Gravity Gradient Measurement Using Rotating Symmetric Accelerometers
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Solution Overview
Problem
Current gravity gradient measurement methods require complex and costly instruments with multiple accelerometers to measure full-tensor gravity gradients, especially for non-diagonal components, which increases complexity and cost.
Innovation Solution
A gravity gradient measurement apparatus using a turntable with two three-axis accelerometers symmetrically arranged and spaced, along with a measurement module that determines gravity gradients using acceleration values, simplifying the measurement process and reducing the number of required accelerometers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple accelerometers (more than six) are used to measure full-tensor gravity gradient with three orthogonal rotating axes, then measurement completeness is improved, but device complexity and cost increase greatly
Solution Approach 1:
The patent divides the gravity gradient measurement into two stages: first measuring diagonal components (Γxx, Γyy, Γzz) directly using accelerometers positioned at vertices of an equilateral triangle, then measuring non-diagonal components (Γxy, Γxz, Γyz) through rotational motion. This segmentation allows using fewer accelerometers (three instead of six or more) while still achieving full-tensor measurement capability.
Solution Approach 2:
The patent introduces rotational motion of the accelerometer array around the vertical axis to dynamically measure non-diagonal gravity gradient components. By rotating the three accelerometers at known angular velocity and analyzing the time-varying acceleration signals, the system can extract non-diagonal components without requiring additional accelerometers or complex static configurations.
2Measurement precision
If additional angular accelerometers are used to measure non-diagonal components and eliminate dynamic errors, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent replaces the need for mechanical angular accelerometers with a computational approach. By precisely controlling the rotational motion and using mathematical models to process the acceleration signals from the three linear accelerometers, the system extracts non-diagonal components and eliminates dynamic errors through signal processing rather than additional mechanical sensors.
3Measurement precision
If six or more accelerometers are combined to measure full-tensor gravity gradient, then measurement completeness is improved, but manufacturing cost and system complexity increase
Solution Approach 1:
The three accelerometers in the patent serve multiple functions: they measure diagonal gravity gradient components directly, and through rotational motion, they also measure non-diagonal components. This multi-functionality reduces the total number of accelerometers needed from six or more to just three, simplifying manufacturing and reducing cost while maintaining full-tensor measurement capability.
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
Enables efficient and accurate measurement of full-tensor gravity gradients with a simpler apparatus, reducing complexity and cost while maintaining high precision.
Implementation Method 1
Gravity gradient measurement began with the survey and exploration of oil and gas... the gravity gradient reflects the change rate of gravity along different directions in the space
Implementation Method 2
the vacuum layer is arranged on the turntable and defining a first chamber with the turntable, the first three-axis accelerometer and the second three-axis accelerometer are located in the first chamber
Data Source
AI summary
Provided is a gravity gradient measurement apparatus and measuring method, wherein a turntable rotates horizontally around an earth-vertical axis, a vacuum layer is arranged on the turntable defining a first chamber, a first three-axis accelerometer and a second three-axis accelerometer are located in the first chamber, the first three-axis accelerometer and the second three-axis accelerometer are arranged symmetrically on an x axis with respect to an origin of coordinates. Both the first three-axis accelerometer and the second three-axis accelerometer have a distance of R from the origin of coordinates. The first three-axis accelerometer and the second three-axis accelerometer are arranged symmetrically on an z axis with respect to the origin of coordinates, and the first three-axis accelerometer and the second three-axis accelerometer are spaced at a distance of h on the z axis. The measurement module uses measurements of the accelerometers to determine gravity gradients on the coordinate axes.