PNNL-13501 - Pacific Northwest National Laboratory

Autonomous Ultrasonic Probe for Process Measurements
Richard A. Pappas, James A. Fort, James M. Prince, Larry D. Reid, Gerald P. Morgen
Study Control Number: PN00012/1419
Ultrasonic probes can become effective real-time sensors for process monitoring and control. Ultrasonic methods are
proven performers for continuous, noninvasive monitoring of fluids during processing and conveyance. The applications
of this technology share a common set of measurement parameters, including signal time-of-flight and amplitude.
Project Description
This project applied novel signal processing techniques
and automated signal mixing designs to making highprecision
measurements of time-of-flight and amplitude.
These features were incorporated into the design of an
autonomous ultrasonic probe. The end deliverable is a
demonstration device that develops and captures the
technology necessary for the fabrication of an
autonomous ultrasonic probe.
Introduction
Ultrasonic methods are proven performers for continuous,
noninvasive monitoring of fluids during processing and
conveyance. The myriad of applications share a common
set of measurement parameters: signal time-of-flight and
amplitude. One, or both, of these two parameters are
measured whether the need is to determine liquid fill
level, identify liquid contents, or measure fluid flow rates.
Technical limitations for many applications in the
processing and transporting of hazardous waste and
industrial chemical reactor gas-solids include a means to
automate ultrasonic time-of-flight and amplitude
measurements at lower frequencies (200 kHz to 500 kHz).
A prototype ultrasonic probe using advanced signal
processing techniques to provide automated time-of-flight
and amplitude outputs was the product of this research.
Approach
The prototype device on a single, bench-top electronics
board included a custom design for signal mixing and a
Texas Instruments, TMS320C31 Floating Point Digital
Signal Processor. The device provides two direct current
voltage signals and a parallel interface for outputs of the
time-of-flight and amplitude. Time gating and amplitude
threshold are adjustable by software and electronic
potentiometers on the board with subsequent designs
providing for remote programmable settings.
Results and Accomplishments
The product of this research was a demonstration device
that develops and captures the technology necessary for
the fabrication of an autonomous ultrasonic probe. The
demonstration probe resides in a bench-top configuration
(see Figure 1). The next generation device will be a small
device that possesses the application simplicity of a
thermocouple or accelerometer. It can be installed on
process vessels and transport lines and can be
programmed for the specific application needs. Its high
degree of automation and low frequency of operation will
allow for an extension of noninvasive ultrasonics into
difficult and severe environments encountered when
dealing with hazardous waste and industrial chemical
manufacturing. The probe concept will incorporate
advanced communication technologies, such as wireless
techniques.
Figure 1. Autonomous ultrasonic probe demonstration
prototype device
Sensors and Electronics 383