Ultrasonic Flow Measurement Using Time-Interleaved Pulses
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Solution Overview
Problem
Existing ultrasonic flow sensing technologies have a low update rate due to multiple reflections/echoes following each ultrasonic pulse transmission, which is insufficient for applications requiring higher rates, such as continuous positive airway pressure (CPAP) machines or ventilators.
Innovation Solution
The implementation of a method where ultrasonic pulses are transmitted and received in a time-interleaved manner, allowing for increased update rates by initiating new pulses before echoes from previous pulses have fully died down, and using frequency modulation to reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultrasonic pulses are transmitted sequentially waiting for echoes to die down, then echo interference is minimized, but the update rate remains low (less than 50 Hz)
Solution Approach 1:
The system predicts the expected arrival time of echoes based on previous pulse transmission and reception timing. Using this prediction, it initiates the next ultrasonic pulse transmission before the previous echoes have fully died down, thereby overlapping the transmission timing with the echo decay period and achieving high update rates without significant echo interference
Solution Approach 2:
The system dynamically adjusts the pulse transmission timing based on real-time echo characteristics. By continuously monitoring when echoes actually arrive and die down, the system adapts the next pulse transmission time to optimize both update rate and echo interference minimization, making the timing flexible rather than fixed
2Productivity
If ultrasonic pulses are transmitted at high update rates (≥2 KHz), then the update rate requirement is met, but echo interference increases
Solution Approach 1:
The system performs preliminary prediction of echo arrival times based on the speed of sound in the medium and the known distance between transducers. This prediction allows the system to schedule high-rate pulse transmissions (≥2 KHz) in advance, ensuring that new pulses are sent at optimal moments when previous echoes have sufficiently decayed, thus maintaining high update rates while controlling echo interference
Solution Approach 2:
The system uses feedback from actual echo reception timing to continuously refine its prediction model. By comparing predicted echo arrival times with actual received times, the system adjusts future pulse transmission timing to account for variations in flow conditions and temperature, thereby maintaining high update rates while minimizing echo interference in dynamic environments
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 enhances the update rate of ultrasonic flow measurement to meet the requirements of high-demand applications like CPAP machines and ventilators by minimizing echo interference and optimizing signal processing.
Implementation Method 1
transmit a first set of ultrasonic pulses using the first ultrasonic transmitter
Implementation Method 2
measure upstream and downstream time-of-flight (TOF) information of ultrasonic pulses
Implementation Method 3
multiple reflections/echoes following each ultrasonic pulse transmission in the tube
Implementation Method 4
multiple reflections/echoes following each ultrasonic pulse transmission
Data Source
AI summary
A method includes at a first time, transmitting a first set of ultrasonic pulses from a first location. The method also includes, at a second time, receiving the first set of ultrasonic pulses at a second location. The method also includes, at a third time, transmitting a second set of ultrasonic pulses from the second location. The method also includes, at a fourth time, receiving a first echo of multiple echoes of the first set of ultrasonic pulses at the second location, in which the third time is the same as the first time, or is between the second time and the fourth time. The method also includes, at a fifth time, receiving the second set of ultrasonic pulses at the first location; and providing a flow rate measurement between the first and second locations based on the first time, the second time, the third time, and the fifth time.