Design of a Full-Range Capacitive Sensor Extensometer Using a High-Precision Ultrasonic Motor

Extensometers are critical instruments for accurately measuring small displacements in terrain deformation monitoring. Conventional extensometers often employ eddy current displacement sensors or differential transformer sensors, which are constrained by structural limitations that hinder their abil...

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Main Authors: Chen Dou, Wenbo Wang, Hong Li, Yunkai Dong, Weiwei Zhan, Liheng Wu, Jiaxin Chen
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Sensors
Subjects:
Online Access:https://www.mdpi.com/1424-8220/25/4/1012
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author Chen Dou
Wenbo Wang
Hong Li
Yunkai Dong
Weiwei Zhan
Liheng Wu
Jiaxin Chen
author_facet Chen Dou
Wenbo Wang
Hong Li
Yunkai Dong
Weiwei Zhan
Liheng Wu
Jiaxin Chen
author_sort Chen Dou
collection DOAJ
description Extensometers are critical instruments for accurately measuring small displacements in terrain deformation monitoring. Conventional extensometers often employ eddy current displacement sensors or differential transformer sensors, which are constrained by structural limitations that hinder their ability to meet high-precision requirements. The capacitive micro-displacement sensor has a high precision of up to 0.1 µm, but it is typically limited by its measurement range, making it unsuitable for directly capturing rapidly changing geological phenomena such as earthquakes and landslides. This range limitation can result in exceedance and measurement errors, severely compromising the reliability and timeliness of the data. To address these challenges, this study introduces a novel design for a full-range capacitive sensor extensometer powered by a high-precision ultrasonic motor. The system integrates an ultrasonic motor with high-sensitivity capacitive sensors, enhanced by a grating scale and PID control algorithms. By enabling real-time signal processing and adaptive correction, the proposed design ensures a wide measurement range while significantly improving the measurement stability and accuracy. Laboratory experiments and field validations confirm the extensometer’s performance, achieving a resolution of 2.0 × 10<sup>−11</sup> strain, a linearity of 0.024%, and a calibration repeatability of 0.06%. These results meet the stringent requirements of terrain deformation observation and establish the extensometer as a robust solution for micro-displacement measurements. This innovative design enhances the reliability of terrain deformation monitoring and contributes to the advancement of rock mechanics observation technologies.
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spelling doaj-art-ec28b4f8dd1e4585b57967b9ca6be85a2025-08-20T02:04:06ZengMDPI AGSensors1424-82202025-02-01254101210.3390/s25041012Design of a Full-Range Capacitive Sensor Extensometer Using a High-Precision Ultrasonic MotorChen Dou0Wenbo Wang1Hong Li2Yunkai Dong3Weiwei Zhan4Liheng Wu5Jiaxin Chen6Ministry of Emergency Management, National Institute of Natural Hazards, Beijing 100085, ChinaMinistry of Emergency Management, National Institute of Natural Hazards, Beijing 100085, ChinaMinistry of Emergency Management, National Institute of Natural Hazards, Beijing 100085, ChinaMinistry of Emergency Management, National Institute of Natural Hazards, Beijing 100085, ChinaMinistry of Emergency Management, National Institute of Natural Hazards, Beijing 100085, ChinaMinistry of Emergency Management, National Institute of Natural Hazards, Beijing 100085, ChinaMinistry of Emergency Management, National Institute of Natural Hazards, Beijing 100085, ChinaExtensometers are critical instruments for accurately measuring small displacements in terrain deformation monitoring. Conventional extensometers often employ eddy current displacement sensors or differential transformer sensors, which are constrained by structural limitations that hinder their ability to meet high-precision requirements. The capacitive micro-displacement sensor has a high precision of up to 0.1 µm, but it is typically limited by its measurement range, making it unsuitable for directly capturing rapidly changing geological phenomena such as earthquakes and landslides. This range limitation can result in exceedance and measurement errors, severely compromising the reliability and timeliness of the data. To address these challenges, this study introduces a novel design for a full-range capacitive sensor extensometer powered by a high-precision ultrasonic motor. The system integrates an ultrasonic motor with high-sensitivity capacitive sensors, enhanced by a grating scale and PID control algorithms. By enabling real-time signal processing and adaptive correction, the proposed design ensures a wide measurement range while significantly improving the measurement stability and accuracy. Laboratory experiments and field validations confirm the extensometer’s performance, achieving a resolution of 2.0 × 10<sup>−11</sup> strain, a linearity of 0.024%, and a calibration repeatability of 0.06%. These results meet the stringent requirements of terrain deformation observation and establish the extensometer as a robust solution for micro-displacement measurements. This innovative design enhances the reliability of terrain deformation monitoring and contributes to the advancement of rock mechanics observation technologies.https://www.mdpi.com/1424-8220/25/4/1012extensometerterrain deformation observationultrasonic motorcapacitive sensormeasurement range extensionPID control
spellingShingle Chen Dou
Wenbo Wang
Hong Li
Yunkai Dong
Weiwei Zhan
Liheng Wu
Jiaxin Chen
Design of a Full-Range Capacitive Sensor Extensometer Using a High-Precision Ultrasonic Motor
Sensors
extensometer
terrain deformation observation
ultrasonic motor
capacitive sensor
measurement range extension
PID control
title Design of a Full-Range Capacitive Sensor Extensometer Using a High-Precision Ultrasonic Motor
title_full Design of a Full-Range Capacitive Sensor Extensometer Using a High-Precision Ultrasonic Motor
title_fullStr Design of a Full-Range Capacitive Sensor Extensometer Using a High-Precision Ultrasonic Motor
title_full_unstemmed Design of a Full-Range Capacitive Sensor Extensometer Using a High-Precision Ultrasonic Motor
title_short Design of a Full-Range Capacitive Sensor Extensometer Using a High-Precision Ultrasonic Motor
title_sort design of a full range capacitive sensor extensometer using a high precision ultrasonic motor
topic extensometer
terrain deformation observation
ultrasonic motor
capacitive sensor
measurement range extension
PID control
url https://www.mdpi.com/1424-8220/25/4/1012
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