Three-Coil Inductor Arrays for Non-Destructive Pavement Deformation Mapping
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Solution Overview
Problem
Existing methods for monitoring pavement deformation fail to distinguish the contribution of individual layers to total deformation, are costly, and are invasive, lacking non-destructive 3D measurement capabilities.
Innovation Solution
A system using three inductor coils on PCBs positioned between pavement layers, allowing triangulation for precise 3D measurement of deformations by measuring magnetic coupling, without requiring trench openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional single-coil inductor cells are used for deformation measurement, then the device is simple to manufacture and low cost, but it cannot distinguish horizontal rotations and translations from vertical translations, leading to reading errors
Solution Approach 1:
The patent transitions from a single-coil system (one-dimensional measurement) to a triad of coils arranged in an orthogonal configuration (three-dimensional measurement). This spatial arrangement enables the system to distinguish between vertical translations and horizontal rotations/translations by measuring magnetic coupling variations from multiple directional perspectives, thereby resolving the measurement ambiguity while maintaining coil manufacturing simplicity.
Solution Approach 2:
The measurement function is segmented across three independent coils instead of relying on a single coil. Each coil in the triad measures a specific component of the deformation vector, and the individual measurements are integrated to provide comprehensive three-dimensional deformation analysis, improving measurement precision without complicating the manufacturing of individual coil elements.
2Measurement precision
If LVDT or MDD instruments are used for monitoring plastic deformations, then measurement capabilities are improved, but the installation becomes more invasive and causes changes in the pavement structure at the monitoring point
Solution Approach 1:
The patent replaces mechanical measurement instruments (LVDT, MDD) that require physical contact and anchoring in the pavement with a magnetic field-based inductor coil system. The coils are positioned between pavement layers without requiring invasive installation, as they measure deformation through magnetic coupling variations caused by changes in distance and orientation between the coil pairs, thereby eliminating structural intrusion while maintaining measurement precision.
Solution Approach 2:
The magnetic field acts as an intermediary between the measurement system and the pavement structure. Instead of directly contacting or anchoring into the pavement, the inductor coils transmit measurement signals through the magnetic field, allowing non-invasive monitoring of plastic deformations by detecting changes in magnetic coupling caused by pavement layer displacements.
3Device complexity
If surface measurements only are used for monitoring pavement deformation, then the measurement system is simple, but it assesses the pavement in an integrated manner without observing the contribution of each layer to total deformation
Solution Approach 1:
The patent segments the pavement structure into discrete measurable layers by positioning inductor coil pairs at specific interfaces between pavement layers. Each coil pair measures the deformation contribution of its specific layer, and the individual layer measurements are then integrated to provide both detailed layer-specific analysis and overall pavement deformation assessment, thereby recovering the lost information about individual layer contributions.
Solution Approach 2:
The patent adds a vertical dimension to surface measurements by positioning measurement coils between pavement layers at different depths. This three-dimensional measurement configuration enables the system to distinguish and quantify the deformation contribution of each individual layer, transforming the measurement capability from integrated surface-only assessment to layered depth-resolved monitoring.
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 non-destructive, cost-effective assessment of individual pavement layer contributions to deformation, improving durability and reducing costs by avoiding invasive methods.
Implementation Method 1
A signal with known frequency and amplitude is applied to the transmitter, inducing a magnetic field around the same. The oscillation of this magnetic field, in turn, induces a current in the receiver cell coil
Implementation Method 2
The ratio between the output signal and the input signal is called coupling, which is maximum when the devices touch and decays as they are moved apart. By calibrating a pair of coils for different known distances, it is possible to infer unknown distances based on the observed coupling
Data Source
AI summary
The invention consists of a system comprising an emitting PCB 10 and one or more receiving PCBs 10, each PCB comprising three coils. The one or more receiving PCBs 10 are positioned on pavement layers while the pavement is being prepared. After the pavement is complete, tests are performed to cause deformations in the pavement. The emitting PCB 10 is positioned on the pavement surface so as to form a pair with one of the receiving PCBs 10. A signal is emitted by a signal generator 20 to the emitting PCB 10, inducing a magnetic field in its coils, which in turn is captured by the coils of the receiving PCB 10 of the pair. The signal resulting in the receiving PCB 10 is captured by a signal receiver 20 that determines the coupling between the pair of PCBs 10. Based on previous calibrations, it is possible to determine the distance between the pair of PCBs after the tests based on the determined coupling. Since the distance before the tests is known, it is possible to determine the new position of the receiving PCB 10 and, consequently, the deformation suffered by the layer where the receiving PCB 10 is located and the contribution of this layer to the total deformation of the pavement. Furthermore, the use of the set of three coils allows an estimate of any horizontal displacements or rotations that may occur between the pavement layers.