Rotational Gravity Gradiometer Noise Isolation

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Solution Overview

Problem

Existing gravity gradiometers face challenges in accurately measuring gravitational field gradients and detecting subsurface features due to limitations in their design and noise sensitivity, particularly in applications like subsurface resource detection and spacecraft attitude control.

Innovation Solution

A rotational gravity gradiometer with orthogonal members and a drive member, equipped with sensor elements that detect movement and generate signals in response to deflections caused by external masses, allowing for precise measurement of gravitational gradients by rotating the members and isolating the sensing material from external noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional gravity gradiometer designs are used, then the device can measure gravitational field gradients, but the device complexity increases due to requirements for flexural pivots and torsion springs

Engineering Contradiction:

Improvegravitational field gradient measurementVSAvoidgimbal arrangement with flexural pivot and torsion spring

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent removes the complex gimbal arrangement, flexural pivots, and torsion springs from the gravity gradiometer design. Instead, it uses a simplified structure where proof masses are directly suspended and sensed by capacitive sensors, extracting only the essential gravitational measurement function while eliminating unnecessary mechanical complexity

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical gimbal system with capacitive sensing elements. The position of proof masses is detected electrically through capacitive coupling rather than through mechanical linkages, pivots, and springs, substituting a mechanical system with an electrical field-based system

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If sensor elements are positioned close to mass units for sensing movement, then measurement precision improves, but noise sensitivity increases

Engineering Contradiction:

Improvemass unit movement detectionVSAvoidexternal noise interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces capacitive coupling as an intermediary between the proof masses and the sensing elements. The capacitive sensors detect mass position through electric field coupling without direct physical contact or close proximity, allowing precise measurement while maintaining electrical isolation that reduces noise interference

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces direct mechanical contact sensing with capacitive field-based sensing. This substitution allows the sensor elements to detect mass unit positions through electric field interactions rather than physical contact, improving precision while reducing susceptibility to mechanical noise and vibration

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 the detection of subtle variations in the Earth's gravitational field, facilitating the identification of subsurface features, resource prospecting, and improved spacecraft control, while reducing noise interference and enhancing sensitivity.

Implementation Method 1

The sensor elements generate a signal in response to deflection of the support arm induced by an external mass

Methodology Applied

Scientific EffectGravitational force: Gravitation

Implementation Method 2

The drive member is coupled to the motor to drive the first member and the second member rotationally

Methodology Applied

Scientific EffectRotational motion:

Data Source

PatentUS9632208B2Rotational gravity gradiometer

Publication Date: 2017.04.25 ILMARINEN ENG LLC

AI summary

A rotational gravity gradiometer includes a first member, a second member, a drive member and a motor. The first member is disposed above the second member orthogonal to and centered with respect to the second member. The first member includes support arms extending from the center of the first member. The second member includes a second pair of support arms extending from a center point of the second member. A mass unit is attached at a distal end of the respective first member and second member. A sensor element is attached between each mass unit a connection point of the opposite member for sensing movement of the mass unit. The drive member is coupled to the motor to drive the first member and the second member rotationally. The respective sensor elements generate a signal in response to deflection of the support arm induced by an external mass.