Ultrasound Flow Measurement Microcontroller Signal Processing

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Solution Overview

Problem

Traditional ultrasound flow measurement systems face challenges in accurately measuring air flow in ducts due to signal damping and low signal strength, leading to reduced precision and increased noise.

Innovation Solution

The system employs a microcontroller-based electronic system with transducers that switch between transmission and reception, using band pass filtration and complex number processing to enhance signal amplitude and phase detection, along with automatic gain control and voltage followers to maintain impedance reciprocity and reduce noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If ultrasound beams are transmitted through air in ducts for flow measurement, then flow measurement capability is achieved, but signal damping increases and signal strength decreases

Engineering Contradiction:

Improveflow measurement precisionVSAvoidsignal strength

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The system uses periodic transmission of ultrasound beams in alternating directions through the duct. Transducers switch between transmitting and receiving modes at regular intervals, creating periodic measurement cycles that enable continuous flow monitoring while managing signal energy requirements

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

Voltage followers are introduced as intermediary circuit elements between the transducers and the measurement system. These voltage followers act as impedance buffers that maintain signal integrity and reduce noise without requiring additional signal energy, thereby addressing the signal strength limitation

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If signal amplification is increased to overcome damping, then signal strength improves, but noise increases

Engineering Contradiction:

Improvesignal strengthVSAvoidnoise

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The system replaces analog signal amplification with digital signal processing. Received analog signals are converted to digital form, then processed using digital filtering and correlation algorithms that can enhance signal strength without proportionally amplifying noise, thereby solving the signal-to-noise tradeoff

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system employs feedback mechanisms where received signals are correlated with transmitted signal patterns. This feedback approach allows the system to identify and enhance genuine signal components while suppressing random noise, achieving signal strengthening without proportional noise increase

Inventive Principle:

Principle #23Feedback

3Measurement precision

If complex number processing and digital filtering are applied, then measurement precision improves, but device complexity increases

Engineering Contradiction:

Improveamplitude and phase detection precisionVSAvoidelectronic system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex analog filtering circuits with digital filtering implemented through software algorithms. Complex number processing is performed digitally on sampled signals, achieving precise amplitude and phase detection without requiring complex analog circuitry, thereby reducing device complexity while maintaining high measurement precision

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 results in highly precise flow measurement with reduced standard deviations, enabling efficient air flow measurement in ducts using relatively simple and inexpensive transducers.

Implementation Method 1

a flow duct, which flow duct comprises at least two transducers, which transducers generate at least one beam of ultrasound in the flow duct

Methodology Applied

Scientific EffectUltrasound: Ultrasound

Implementation Method 2

which receiver circuit comprises at least a band pass filter, which band pass filter is further connected to a microcontroller

Methodology Applied

Scientific EffectBand pass filtration: Filter (electronic)

Implementation Method 3

which microcontroller multiplies each value of the frame which is a complex number with the magnitude one and a phases representing the transmitted frequency and phase, which microprocessor generates imaginary values and a real values, which imaginary values and a real values low pass filtrated in a digital filter

Methodology Applied

Scientific EffectPhase detection:

Implementation Method 4

which digital converter converts the analogue signal into digital data samples representing at least transit times and time difference

Methodology Applied

Scientific EffectTime of flight: Time of Flight

Data Source

PatentUS9335194B2System or a method for measuring flow of fluid or gas

Publication Date: 2016.05.10 SCI FLOW LAB AS

AI summary

A system or a method for measuring flow in a flow duct has at least two ultra sound transducers. The flow of air in a duct is measured by one or more transducers transmitting beams of ultra sound controlled by a microcontroller based electronic system in which the microcontroller stores a vector of data samples for each direction of transmission, which vector includes an appropriate number of N samples forming a frame, the microcontroller multiplying each value of the frame which a complex number. Based on the result, the microcontroller calculates the flow in the duct. As a result, an efficient flow measurement of air flowing in a duct can be achieved.