Inductive Gap Sensing on Flexible Substrates for Shim Profiling
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Solution Overview
Problem
Existing measurement systems for air gaps in mechanical structures are limited in their ability to accurately measure miniaturized gaps, especially in hard-to-access spaces, and cannot simultaneously take multiple measurements across an area, which hampers the production of shims for precise alignment and increases manufacturing costs.
Innovation Solution
A resonant inductive coupling-based sensing system using flexible hybrid electronics with arrays of inductor-capacitor sets on substrates, allowing for remote measurement and two-dimensional profiling of air gaps, enabling accurate and simultaneous measurement of gap sizes across an area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spring-based mechanical measurement systems are used, then measurement is possible without regard to material type, but the system is limited to measuring gaps larger than the compressed height of the spring (typically about 22 mils)
Solution Approach 1:
The patent replaces spring-based mechanical measurement systems with an inductive coupling-based electrical measurement system. The inductive sensor uses electromagnetic fields to measure gaps, eliminating the physical contact and compressed height limitations of mechanical springs, thereby enabling measurement of smaller gaps while maintaining material-agnostic capability.
Solution Approach 2:
The patent changes the measurement parameter from mechanical displacement to electrical inductive coupling characteristics. By measuring changes in inductive coupling strength or resonant frequency as a function of gap distance, the system achieves precise measurement of miniaturized gaps that are too small for spring-based mechanical systems.
2Measurement precision
If capacitive measurement systems are used, then air gaps down to about 7.5 mils can be measured, but the systems are not agnostic to the conductive materials defining the gap
Solution Approach 1:
The patent replaces capacitive electrical measurement with inductive coupling measurement. Inductive sensors measure gaps through electromagnetic induction between two inductors, which does not require direct electrical contact or conductive materials, thereby maintaining material-agnostic capability while achieving measurement of smaller gaps.
Solution Approach 2:
The patent introduces an inductive field as an intermediary between the measurement system and the gap. The inductive coupling mechanism uses magnetic field lines that can penetrate non-conductive materials, allowing measurement through air gaps and non-conductive barriers without being affected by material conductivity variations.
3Measurement precision
If traditional measurement systems are used, then single-point measurements can be taken, but multiple measurements across an area cannot be taken simultaneously
Solution Approach 1:
The patent segments the measurement area into a two-dimensional array of discrete measurement points. Each point in the array has corresponding inductor elements on both substrates that can be independently activated to perform measurements, enabling simultaneous multi-point measurement across the entire area.
Solution Approach 2:
The patent transitions from single-point linear measurement to two-dimensional planar measurement by arranging inductor elements in a grid pattern on both substrates. This dimensional expansion allows simultaneous measurement across the entire surface area, dramatically increasing measurement throughput while maintaining precision at each point.
4Measurement precision
If conventional gap measurement methods are used, then measurements can be taken in accessible spaces, but miniaturized gaps in hard-to-access spaces cannot be accurately measured
Solution Approach 1:
The patent uses flexible thin-film substrates to mount the inductor elements, allowing the measurement system to conform to complex geometries and access hard-to-reach spaces. The flexible nature of the substrates enables deployment in confined areas where rigid measurement devices cannot reach, while maintaining measurement precision.
Solution Approach 2:
The patent replaces mechanical probe-based measurement systems with inductive coupling sensors that can be integrated into compact forms. The inductive measurement mechanism requires minimal intrusion into the gap space, enabling accurate measurement of miniaturized gaps in hard-to-access locations without mechanical interference.
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 solution provides accurate and efficient measurement of air gaps, enabling the production of shims that improve first-time quality and reduce manufacturing costs by allowing precise alignment and measurement of miniaturized gaps in hard-to-access spaces.
Implementation Method 1
driving a first inductor of the first LC circuit with a first alternating current to produce a changing magnetic flux that passes through a second inductor of the second LC circuit
Implementation Method 2
A resonant inductive coupling-based sensing system is configured to remotely measure an air gap
Data Source
AI summary
Systems and methods for measuring air gaps between opposing surfaces of two structural components. In one application, such measurements are used to fabricate a shim that fills the air gap between two structural members, such as parts of an aircraft. The resonant inductive coupling-based sensing system has the capability to remotely measure an air gap using an on-board transmit system. Furthermore, the system has the capability to switch between multiple inductor-capacitor sets such as to simultaneously measure air gaps across an area so that a better profile of the air gap can be determined. The resonant inductive coupling-based gap sensor is configured as signal generating and signal sensing electronics printed or mounted on respective flexible substrates to provide a flexible and portable measurement solution.