Wireless Ultrasonic Sensor Using Time-Equivalent Sampling for Low Power
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Solution Overview
Problem
Current ultrasonic non-destructive evaluation (NDE) devices for monitoring pipe integrity are costly and power-intensive, requiring large batteries and complex system architectures due to high sampling rates and high-frequency signal handling, which increases power consumption and reduces miniaturization potential, and are also hindered by expensive cabling and connector costs, as well as limitations in mesh network range.
Innovation Solution
A wireless, low-power ultrasonic sensor using time-equivalent sampling and integrated A/D converters within a microcontroller, eliminating the need for discrete A/D converters and field-programmable gate arrays (FPGAs), which reduces power consumption, component count, and size, allowing for a single small battery to last for several years and simplifies the system architecture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional ultrasonic NDE devices use high sampling rates and high-frequency signal handling, then measurement precision is improved, but power consumption increases and device size increases
Solution Approach 1:
The patent implements time-equivalent sampling where multiple ultrasonic signals are acquired at a lower sampling rate over different time periods, then combined to achieve the precision equivalent of high-rate sampling. This periodic acquisition approach reduces instantaneous power consumption while maintaining measurement precision through temporal integration of multiple lower-power signal captures.
Solution Approach 2:
The system dynamically adjusts between acquisition mode (ultrasonic signal capture) and processing mode (signal combination and analysis), allowing the device to operate at low power during idle periods while achieving high precision during measurement windows. The microcontroller dynamically manages the A/D converter and signal processing resources to minimize power consumption during non-critical operations.
2Measurement precision
If discrete A/D converters and FPGAs are used for signal processing, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the A/D converter, microcontroller, and signal processing functions into a single integrated unit. The microcontroller's built-in A/D converter directly digitizes ultrasonic signals, and the same microcontroller performs signal processing, combination, and analysis functions that would traditionally require separate FPGAs or discrete A/D converters. This consolidation reduces component count and system complexity while maintaining precision through software-based signal processing.
Solution Approach 2:
The microcontroller serves multiple functions: it triggers ultrasonic signal acquisition, controls the A/D converter, processes digitized signals, combines multiple signals through time-equivalent sampling, and manages wireless communication. This multi-functional approach eliminates the need for dedicated discrete components for each function, reducing overall device complexity while preserving measurement accuracy.
3Duration of action of moving object
If large lithium ion batteries are used to meet battery life requirements, then duration of action is improved, but device size and weight increase
Solution Approach 1:
The device operates in periodic cycles of low-power measurement and data transmission. Ultrasonic signals are acquired at low power using time-equivalent sampling, and wireless data transmission occurs periodically rather than continuously. This periodic operation pattern extends battery life significantly, allowing the use of smaller, lighter batteries to achieve the required 5-10 year operational lifespan.
Solution Approach 2:
The system changes its power consumption parameters by using lower sampling rates during acquisition and transitioning to sleep modes between measurements. The microcontroller manages power states dynamically, reducing current draw during idle periods and during signal processing, thereby extending battery life and enabling the use of smaller battery cells that reduce overall device weight.
4Measurement precision
If manual probe positioning is used for measurements, then measurement precision is improved, but ease of operation deteriorates and access costs increase
Solution Approach 1:
The device is permanently mounted on the asset and performs self-service measurements without requiring manual operator intervention for positioning. The automated sensor systematically acquires ultrasonic signals and processes data independently, eliminating the need for operators to manually position probes while maintaining consistent measurement locations and precision over time.
Solution Approach 2:
The sensor is pre-installed and permanently positioned on the asset before operation begins. This preliminary action establishes a fixed, consistent measurement location that eliminates the variability introduced by manual positioning. The device then automatically performs measurements from this predetermined location, ensuring repeatability and precision without requiring operator presence or manual adjustment.
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 significantly reduces power consumption, lowers the overall capacitance, and decreases the size and cost of the sensor, making it intrinsically safe for hazardous locations and enabling more practical and cost-effective monitoring of pipe integrity with reduced cabling and connector costs, while maintaining accurate signal processing through composite signal generation.
Implementation Method 1
a transducer for converting an analog transmit signal to an ultrasonic transmit signal, and for converting an ultrasonic reflected signal to an analog reflected signal
Implementation Method 2
repeatedly triggering the transmit and receive circuit and the A/D converter to obtain a digitized composite signal through time-equivalent sampling
Implementation Method 3
processing the digitized composite reflected signal to generate an A-scan signal
Implementation Method 4
wirelessly transmitting the data signal based on the A-scan signal for transmission to a discrete collection device
Data Source
AI summary
A sensor for ultrasonically measuring a portion of a structure, the sensor comprising: a transducer for converting an analog transmit signal to an ultrasonic transmit signal, and for converting an ultrasonic reflected signal to an analog reflected signal; a housing integrated with the transducer and containing at least: a processor; a wireless data transmitter for transmitting wirelessly a data signal from the processor; a transmit and receive circuit for transmitting an analog transmit signal to the transducer in response to a transmit trigger from the processor, and for receiving an analog reflected signal from the transducer; an A/D converter for digitizing only a portion of the analog reflected signal in response to a sample trigger from the processor; a battery to supply power to the processor, the wireless data transmitter, the transmit and receive circuit, and the A/D converter; memory operatively connected to the processor and configured to instruct the processor to execute the following steps: repeatedly triggering the transmit and receive circuit and the A/D converter to obtain a digitized composite signal through time-equivalent sampling; processing the digitized composite reflected signal to generate an A-scan signal; and wirelessly transmitting the data signal based on the A-scan signal for transmission to a discrete collection device.