Impedance Instrument Digital Signal Processing for Material Condition
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Solution Overview
Problem
Current inspection methods for material condition, particularly in high-value assets like aircraft and pipelines, are inefficient due to high equipment costs, time-consuming processes, and the need for extensive disassembly, and they struggle to accurately detect defects such as cracks, corrosion, and fatigue without causing damage.
Innovation Solution
An impedance instrument and method that generate in-phase and quadrature reference signals to measure impedance components simultaneously using a sensing channel with an analog-to-digital converter, allowing for real-time processing of digitized samples to determine material properties like conductivity and permeability, and a system for estimating properties using multivariate inverse methods and precomputed databases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional electromagnetic inspection methods are used, then measurement accuracy is improved, but inspection time increases due to settling time requirements
Solution Approach 1:
The patent replaces the traditional analog multiplication and low-pass filtering system with a digital signal processing system. The analog-to-digital converter digitizes the sensor output, and digital signal processing algorithms perform the multiplication and filtering operations in the digital domain, eliminating the settling time constraints of analog low-pass filters while maintaining measurement accuracy.
Solution Approach 2:
The patent changes the processing domain from analog to digital, fundamentally altering the system parameters. By digitizing the signal early in the processing chain and performing all subsequent operations digitally, the system achieves faster processing speeds and eliminates the time constants associated with analog filter settling, thereby reducing inspection time while preserving measurement precision.
2Productivity
If multiple impedance components are measured simultaneously, then productivity is improved, but device complexity increases
Solution Approach 1:
The patent implements a universal digital signal processing architecture that can simultaneously measure multiple impedance components (real and imaginary parts at different frequencies) using the same hardware resources. The digital signal processing system processes multiple frequency components and extraction operations through a unified computational framework, enabling simultaneous measurement without requiring separate dedicated analog processing paths for each component.
Solution Approach 2:
The patent transitions from measuring impedance components sequentially in the time domain to simultaneously extracting multiple components in the frequency domain. By utilizing Fourier transform techniques and frequency-domain analysis, the system can extract real and imaginary parts at multiple frequencies from a single composite signal, effectively adding dimensional capability without increasing hardware complexity.
3Loss of time
If digital signal processing is used instead of analog filtering, then inspection time is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent replaces the physical analog filtering mechanism with a computational digital processing system. Instead of relying on the physical characteristics and tolerance stacks of analog filter components, the system uses software-based signal processing algorithms that can achieve high precision through computational mathematics, thereby reducing the impact of manufacturing tolerances while eliminating settling time delays.
Solution Approach 2:
The patent creates a digital replica or model of the signal processing function rather than implementing it physically in the analog domain. By digitizing the signal and performing processing operations through mathematical algorithms, the system achieves precise control over processing parameters without being constrained by the physical manufacturing tolerances of analog components, effectively copying the filtering function in the digital realm where precision is determined by computational accuracy rather than manufacturing precision.
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 approach reduces inspection time and costs by providing accurate, non-destructive measurements of material properties, enabling efficient monitoring of defects and asset condition, and allowing for real-time assessment of weld quality and corrosion susceptibility.
Implementation Method 1
A signal generator is configured to generate an in-phase reference signal, a quadrature reference signal, and an electrical signal oscillating at a first excitation frequency
Implementation Method 2
The sensing channel has an analog-to-digital converter to digitize a response signal and a module to process successive digitized samples of the digitized response signal with each of the in-phase and quadrature reference signals, to produce an impedance measurement
Data Source
AI summary
System and method for characterizing material condition. The system includes a sensor, impedance instrument and processing unit to collect measurements and assess material properties. A model of the system may be used to enable accurate measurements of multiple material properties. A cylindrical model for an electromagnetic field sensor is disclosed for modeling substantially cylindrically symmetric material systems. Sensor designs and data processing approaches are provided to focus the sensitivity of the sensor to localize material conditions. Improved calibration methods are shown. Sizing algorithms are provided to estimate the size of defects such as cracks and corrosion. Corrective measures are provided where the actual material configuration differs from the data processing assumptions. Methods are provided for use of the system to characterize material condition, and detailed illustration is given for corrosion, stress, weld, heat treat, and mechanical damage assessment.