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

Area of Science:

• Geophysics and Rock Mechanics
• Instrumentation and Measurement Science

Background:

• Conventional extensometers using eddy current or differential transformer sensors face structural limitations impacting high-precision terrain deformation monitoring.
• Capacitive micro-displacement sensors offer high precision but are limited by measurement range, hindering real-time capture of rapid geological events like earthquakes and landslides.

Purpose of the Study:

• To develop a novel full-range capacitive sensor extensometer overcoming the range limitations of existing micro-displacement sensors.
• To enhance the stability, accuracy, and reliability of terrain deformation monitoring for geological phenomena.

Main Methods:

• Integration of a high-precision ultrasonic motor with high-sensitivity capacitive sensors.
• Incorporation of a grating scale and Proportional-Integral-Derivative (PID) control algorithms for adaptive correction.
• Real-time signal processing to ensure wide measurement range and improved stability.

Main Results:

• Achieved a high resolution of 2.0 × 10^-11 strain.
• Demonstrated excellent linearity of 0.024% and calibration repeatability of 0.06%.
• Validated performance through laboratory experiments and field observations, meeting stringent terrain deformation observation requirements.

Conclusions:

• The novel full-range capacitive sensor extensometer provides a robust solution for micro-displacement measurements in terrain deformation monitoring.
• This advancement enhances the reliability of observing geological phenomena and contributes to rock mechanics technology.