Sensor data fusion for responsive high resolution ultrasonic temperature measurement using piezoelectric transducers

Anas Hashmi; Alexander N Kalashnikov

doi:10.1016/j.ultras.2019.105969

Sensor data fusion for responsive high resolution ultrasonic temperature measurement using piezoelectric transducers

Ultrasonics. 2019 Nov:99:105969. doi: 10.1016/j.ultras.2019.105969. Epub 2019 Aug 7.

Authors

Anas Hashmi¹, Alexander N Kalashnikov²

Affiliations

¹ Department Electrical and Electronic Engineering, University of Jeddah, University of Jeddah Road, Jeddah, Saudi Arabia.
² Department Engineering and Maths, Sheffield Hallam University, Howard str, Sheffield S1 1WB, UK. Electronic address: a.kalashnikov@shu.ac.uk.

PMID: 31422114
DOI: 10.1016/j.ultras.2019.105969

Abstract

Ultrasonic temperature measurement allows for responsive measurements across an entire ultrasonic pathway, unlike most conventional temperature sensors that respond to the temperature at the point of their placement only after a notable response time. The high cost of required ultrasonic instrumentation can be reduced substantially by using ultrasonic oscillating temperature sensors (UOTS) consisting of inexpensive narrowband piezo transducers and driving electronics. An UOTS produces sustained oscillations at a frequency that relates to the temperature of the medium between the transducers. The existence of thermal hysteresis in UOTS readings, observed experimentally and apparently related to the fundamental properties of piezoelectric materials, makes conversion of the output frequency readings to the temperature values ambiguous. This makes it complicated to calibrate and use UOTS on their own. In the reported experiment (heating, then naturally cooling of a water vessel equipped with both UOTS and conventional sensors), this hysteresis was solved by fusing UOTS data with conventional temperature sensor readings. As the result, the combination of one UOTS plus one conventional reference sensor allowed improving both the temperature resolution and responsiveness of the latter and ambiguity of the readings of the former. Data fusion effectively led to calibrating the UOTS at every change of the conventional sensor's reading, removing any concerns related to the thermal expansion/contraction of the ultrasonic pathway itself and/or hysteresis of piezoelectric transducers.

Keywords: Data fusion; High resolution temperature measurement; Temperature sensing; Ultrasonic instrumentation; Ultrasonic non-destructive evaluation; Ultrasonic oscillating temperature sensor.