Air Flow Meter Pulsation Correction via Dynamic Integrator
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Solution Overview
Problem
Existing air flow meters face challenges in rapidly following changes in pulsation states of input signals due to the computational intensity of fast Fourier transform methods, which require long observation times and result in delayed correction of pulsation errors.
Innovation Solution
An air flow meter design that includes a calculation unit with an output signal calculation unit performing exponentiation and an input signal calculation unit, a subtractor, and an integrator, along with a low-pass filter function, allowing for real-time correction of pulsation errors by dynamically adjusting the cutoff frequency based on the instantaneous output signal values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fast Fourier transform is used for frequency analysis, then frequency and pulsation amplitude can be obtained, but calculation time increases exponentially and it takes long to output results
Solution Approach 1:
The patent extracts only the essential pulsation correction function from the complete FFT analysis, implementing a simplified calculation that obtains pulsation amplitude and frequency without performing full spectral analysis. This selective extraction of necessary information reduces computational complexity while maintaining correction effectiveness
Solution Approach 2:
The patent employs a lightweight calculation algorithm that requires minimal computational resources and can be executed rapidly, replacing the computationally intensive FFT. This 'cheap' calculation method sacrifices some analytical depth but provides sufficient accuracy for pulsation correction with dramatically reduced calculation time
2Measurement precision
If predetermined observation time is used in fast Fourier transform, then desired frequency analysis range and resolution are obtained, but it is difficult to follow rapid changes in pulsation state
Solution Approach 1:
The patent implements a dynamic correction approach where the pulsation correction is continuously updated based on current operating conditions rather than using fixed predetermined observation windows. The calculation adapts to changing pulsation states in real-time, allowing the system to follow rapid changes while maintaining accurate frequency analysis range
Solution Approach 2:
The patent pre-calculates and stores correction characteristics for various pulsation conditions, allowing the system to quickly retrieve and apply appropriate corrections without performing lengthy real-time analysis. This preliminary preparation enables rapid response to changing pulsation states while maintaining comprehensive frequency analysis capabilities
Data Source
AI summary
An air flow meter capable of rapidly following a change of a pulsation state of an input signal includes: an air flow rate detection element that generates an input signal Qsen relating to an air flow rate to be measured; and a calculation unit that performs calculation to generate an output signal Qout in response to the input signal Qsen. The calculation unit includes: the output signal calculation unit that performs calculation including exponentiation of raising the power of the output signal Qout by more than one; the input signal calculation unit that performs calculation on the input signal Qsen; the subtractor that obtains the difference between the calculation results by the output signal calculation unit and the input signal calculation unit; and the integrator that integrates the difference obtained by the subtractor, and the output signal Qout is generated based on the output from the integrator.