Acoustic Band-Pass Filter for Seed Flow Monitoring
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Solution Overview
Problem
Existing material flow sensing systems for dry-particulate spreaders face challenges in accurately determining flow rates due to signal overlap from high material flow rates, caused by prolonged impact signatures and microphone saturation, which hinder the counting of individual seed impacts.
Innovation Solution
An acoustic band-pass filter assembly with a series of resonator chambers of varying cross-sectional areas is introduced between the sensor membrane and microphone, limiting low-frequency energy transmission and reducing the overall impact signature duration, preventing microphone saturation and enhancing the accuracy of flow rate determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acoustic energy is transmitted directly from sensor to microphone, then signal strength is maintained, but low frequency resonances cause prolonged impact signatures that lead to signal overlap at high flow rates
Solution Approach 1:
A band-pass filter assembly with resonator chambers is introduced as an intermediary component between the sensor membrane and microphone. This filter selectively transmits high frequency acoustic energy while blocking low frequency resonances, thereby maintaining signal strength for impact detection while eliminating the prolonged low frequency ringout that causes signal overlap.
Solution Approach 2:
The filter assembly changes the frequency parameter distribution of the transmitted acoustic signal by attenuating low frequency components and passing high frequency components. This parameter transformation shortens the impact signature duration in the time domain while preserving the essential impact detection capability.
2Reliability
If acoustic amplitude is increased to improve detection, then signal strength is enhanced, but microphone saturation occurs which artificially extends the impact ringout
Solution Approach 1:
The band-pass filter serves as a protective intermediary that prevents excessive low frequency acoustic energy from reaching the microphone, thereby avoiding saturation while still allowing sufficient high frequency energy for accurate impact detection.
Solution Approach 2:
The filter modifies the amplitude distribution across different frequency parameters, reducing low frequency amplitude that causes saturation while maintaining or enhancing high frequency amplitude that carries the impact detection signal.
3Measurement precision
If individual seed impacts are counted instead of measuring overall acoustic energy, then flow rate measurement precision is improved, but signal processing complexity increases
Solution Approach 1:
The band-pass filter performs preliminary signal conditioning by removing low frequency resonances before the signal reaches the microphone and processing stage. This pre-processing simplifies the subsequent signal analysis required for counting individual impacts, as the filtered signal has reduced overlap and clearer impact signatures.
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
The solution effectively shortens the impact ring-out duration, allowing for accurate estimation of flow rates by eliminating signal overlap and reducing cross-talk, thereby improving the precision of material flow monitoring.
Implementation Method 1
The resonator chambers are configured to transmit acoustic energy between the inlet and the microphone. Each of the plurality of resonator chambers has a different cross-sectional area.
Implementation Method 2
The high frequency components of the impact signature tend to decay faster (likely due to stronger absorption in the sensor materials).
Data Source
AI summary
An acoustic band-pass filter assembly includes an inlet, a microphone configured to receive acoustic energy from the inlet, and a plurality of resonator chambers disposed in series between the inlet and the microphone and configured to transmit acoustic energy between the inlet and the microphone. Each of the plurality of resonator chambers has a different cross-sectional area.