Material Tester Signal Processing for High Sampling Frequency
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Solution Overview
Problem
Conventional measurement devices face challenges in extracting frequency components exceeding the carrier frequency in material testing, leading to increased stray capacitance influences and reduced measurement reliability, especially when higher sampling frequencies are required.
Innovation Solution
A measurement device using a receiving circuit with a sinusoidal wave and its odd harmonic components as a correlation function to extract resistance components from the received signal, allowing for the capture of changes in physical quantities beyond the carrier frequency without increasing the carrier frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the carrier frequency is increased to detect higher frequency components, then the measurement speed and sampling frequency improve, but the influence of stray capacitance between cables increases and measurement reliability decreases
Solution Approach 1:
The patent applies signal processing techniques to convert the harmful effect of stray capacitance into a manageable parameter. By using synchronous detection with correlation functions and spectral analysis, the system processes the capacitive component B (which causes measurement error) through mathematical operations that separate it from the resistance component A (the actual measurement signal), thereby converting the harmful capacitive interference into a distinguishable signal component that can be filtered or compensated.
Solution Approach 2:
The patent changes the approach from increasing the carrier frequency to improve sampling rate to using signal processing parameter changes. Instead of raising the carrier frequency (which increases stray capacitance effects), the system processes the received signal through correlation functions and spectral analysis to extract frequency components up to twice the carrier frequency, achieving high sampling rates without the harmful side effect of increased stray capacitance influence.
2Measurement precision
If the carrier frequency is increased to detect higher frequency components, then the measurement accuracy for dynamic changes improves, but the stray capacitance influence increases and reduces reliability
Solution Approach 1:
The patent converts the harmful stray capacitance effect into a distinguishable signal component through synchronous detection. The correlation function and spectral analysis separate the capacitive component B from the resistance component A, allowing the system to maintain high measurement accuracy for dynamic changes while compensating for or eliminating the harmful influence of stray capacitance on measurement reliability.
Solution Approach 2:
The patent introduces signal processing operations as an intermediary between the detector output and the final measurement result. The correlation function and spectral analysis act as mediators that process the mixed signal containing both resistance and capacitive components, separating and extracting the accurate resistance component while filtering out or compensating for the harmful capacitive effects.
3Loss of time
If the carrier frequency is increased to capture faster changes in physical quantity, then the response speed improves, but the stray capacitance between cables increases and measurement reliability decreases
Solution Approach 1:
The patent converts the harmful stray capacitance influence into a manageable signal component through synchronous detection and spectral analysis. This allows the system to achieve fast response times by processing high-frequency components without suffering from increased measurement unreliability due to stray capacitance, as the signal processing separates and compensates for the capacitive effects.
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 enables the extraction of frequency components exceeding the carrier frequency, improving measurement accuracy and reliability by reducing the impact of stray capacitance, allowing for smoother operation and more precise data acquisition in material testing.
Implementation Method 1
a detector that converts the change in physical quantity generated in an object to be measured into an electric signal
Implementation Method 2
Fourier transformation has been conventionally used as a method of exciting a detector with an AC voltage and extracting components of a force and a displacement from a received signal
Data Source
AI summary
In an FPGA, waveform data to be sent from the FPGA to a DAC is stored, and a logical circuit is configured from a detection circuit for extracting test force value and elongation value signal components from a signal input from an ADC, an offset subtractor, and a gain multiplier. The detection circuit extracts a resistance component proportional to the test force and displacement. In the detection circuit, an expression that includes a harmonic component of an odd multiple of the carrier frequency is used as a correlation function for extracting the resistance component. As a result, it is possible to obtain calculation results at a sampling frequency that is higher than the carrier frequency.