Adaptive Low-Pass Filter for Mass Flow Measurement
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Solution Overview
Problem
Existing mass flow measurement systems face challenges in accurately determining mass flow rates due to noise in vibration-dependent signals caused by varying gas content in liquids, which can lead to delayed adaptation of filters and reduced data rates in time-critical applications.
Innovation Solution
The system employs an adaptive low-pass filter with filter parameters dependent on the gas content of the measured medium, using a control variable that adjusts based on gas-content-dependent fluctuations in natural frequency or damping of measurement tube vibrations, and a weighting function that modifies the contribution of current measured values to filtered outputs based on a time constant that adapts to changing gas content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a low-pass filter is used to filter the measurement signal, then noise is reduced, but the data rate is reduced
Solution Approach 1:
The patent applies a dynamic filtering approach where the filter characteristics are continuously adapted based on the measured signal properties. The system dynamically adjusts the filter order and cutoff frequency based on the spectral content of the measurement signal, allowing optimal noise reduction while maintaining high data rates for time-critical applications.
Solution Approach 2:
The system changes filter parameters (filter order, cutoff frequency) based on the measured signal characteristics. By analyzing the spectral content and adjusting filter parameters accordingly, the system achieves effective noise filtering without unnecessarily reducing the data rate, thus resolving the contradiction between signal quality and productivity.
2Measurement precision
If adaptive filters controlled as a function of noise are used, then noise suppression is improved, but adaptation delay occurs when media properties change suddenly
Solution Approach 1:
The system employs feedback mechanisms where the measured signal properties are continuously monitored and used to adjust filter parameters in real-time. This feedback loop enables rapid adaptation to changing media properties while maintaining effective noise suppression, reducing the adaptation delay inherent in traditional adaptive filters.
Solution Approach 2:
The system performs preliminary analysis of the measurement signal to predict optimal filter parameters before actual filtering occurs. By anticipating parameter changes based on signal trends and media property variations, the system reduces adaptation delay and maintains continuous optimal noise suppression.
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 significantly reduces signal fluctuations, allowing for more accurate and timely determination of mass flow rates while maintaining data integrity, even under changing conditions, thereby enhancing the system's responsiveness and precision.
Implementation Method 1
at least one exciter (8) for exciting vibrations of the measurement tube (A, B) in at least one vibration mode
Implementation Method 2
at least two vibration sensors (14, 16) for detecting vibrations of the measurement tube and for outputting vibration-dependent signals
Data Source
AI summary
Disclosed is a measurement pickup for determining the mass flow rate of a liquid comprising: at least one measurement tube for carrying the liquid having an inlet-side end section and an outlet-side end section; a support body on which the measurement tube is mounted an exciter for exciting vibrations of the measurement tube; at least one vibration sensor for detecting vibrations of the measurement tube; an operating and evaluation circuit for driving the exciter, for receiving the signals of the vibration sensor, and for ascertaining a measured value representing the mass flow rate. The operating and evaluation circuit comprises an adaptive low-pass filter for filtering the sequence of measured values representing the mass flow rate, wherein the low-pass filter has at least one filter parameter dependent on at least one adaptive controlled variable that, for its part, is dependent on the gas content of the test medium.