Spherical Air Bearing Gravity Gradiometer for Rotational Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional gravity gradiometer instruments face significant noise and error due to mechanical contact between gimbals and their supporting structures, leading to sub-optimal stabilization and increased maintenance needs when used on moving platforms.
Innovation Solution
A gravity sensor or gravity gradiometer instrument utilizing a spherical air bearing for rotational isolation, supported by a linear motion stage with passive mechanical suspension and non-contacting electromagnetic actuators, eliminating the need for mechanical bearings and reducing jitter disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional nested gimbals with mechanical bearings and races are used for rotational isolation, then rotational isolation from host vehicle angular motion disturbances is achieved, but jitter disturbances and measurement errors increase due to bearing stiction
Solution Approach 1:
The patent replaces the conventional mechanical gimbal system with magnetic bearing technology. The magnetic bearing suspends the inner gimbal structure without physical contact, eliminating mechanical friction and stiction. This substitution maintains rotational isolation capability while removing the source of jitter disturbances that degrade measurement precision.
Solution Approach 2:
The patent employs an active isolation system using pneumatic or hydraulic actuators to dynamically compensate for vibrations and disturbances. This active control system counteracts external disturbances in real-time, further improving measurement accuracy without relying on passive mechanical isolation that introduces friction.
2Ease of operation
If ball bearings and races are used between gimbals to enable rotation, then rotational freedom is achieved, but stiction causes threshold forces and shock-like jitter disturbances
Solution Approach 1:
The patent replaces mechanical ball bearings with magnetic bearing technology that provides rotational freedom through magnetic fields rather than physical contact. This eliminates static friction entirely, allowing the inner gimbal to rotate freely without threshold forces or shock-like jitter disturbances that occur when overcoming stiction in mechanical bearings.
3Reliability
If flex capsules and slip rings are used to maintain electrical continuity through gimbals, then power and data transmission is maintained, but availability reduces due to maintenance and replacement needs
Solution Approach 1:
The patent replaces mechanical flex capsules and slip rings with wireless power and data transmission technologies. This substitution eliminates wear-prone mechanical contact components that require maintenance and replacement, thereby improving ease of repair while maintaining continuous power and data transmission through the rotating gimbal structure.
4Reliability
If the gravity instrument is mounted on the innermost gimbal structure, then rotational isolation is maximized, but the characteristic dimension of the sensor becomes much less than the overall volume occupied
Solution Approach 1:
The patent replaces the bulky mechanical gimbal structure with a compact magnetic bearing system. This substitution maintains the rotational isolation function while dramatically reducing the overall volume occupied by the instrument assembly, allowing the sensor's characteristic dimension to be much closer to the total volume and improving the sensor-to-system volume ratio.
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 configuration provides effective rotational isolation, minimizes inertial torques, and enhances the accuracy of gravity gradient measurements by eliminating parasitic torques and jitter, while simplifying maintenance and reducing noise.
Implementation Method 1
an upper half of a spherical air bearing or ball supported in a non-contacting manner by a cushion of air above a bearing base
Implementation Method 2
The outer frame sits atop pedestals and air springs which mount to the host vehicle, providing vibration isolation at frequencies above the natural resonance of this passive isolation arrangement
Data Source
AI summary
A non-contacting spherical air bearing-based stable platform for use by a gravity gradiometer instrument (GGI) is provided by attaching a spherical ball-shaped bearing to a rotational stage of the GGI and integrating a concave spherical cup in the linear stage and mounting base assembly of the GGI which is fixedly attached to a host vehicle or platform. The spherical cup supports the spherical ball-shaped bearing on a thin cushion of air provided by a source of compressed air or gas at the concave surface of the spherical cup. The spherical ball-shaped bearing is supported, providing three degrees of rotational freedom of motion without the need for slip rings, flex capsules, races, or mechanical bearings, thereby reducing or eliminating gradient disturbance signals owing to parasitic torques and jitter in the output of the accelerometers of the GGI.