Design of a Differential Capacitive Horizontal Pendulum Tiltmeter

This paper presents a differential capacitive horizontal pendulum tiltmeter based on electrostatic feedback force. The system mainly consists of a horizontal pendulum bob, a triangular platform, a pendulum locking motor, a differential capacitive sensing circuit, an electrostatic feedback circuit, and a sealed protective housing. The electrostatic feedback differential capacitive horizontal pendulum tiltmeter does not introduce a novel tilt measurement principle; its pendulum still adopts the classic Zöllner double-suspension-wire configuration. In this study, engineering improvements were implemented on the conventional quartz horizontal pendulum tiltmeter by replacing quartz fibers with tungsten wires, substituting optical lever sensors with capacitive sensors, and incorporating the electrostatic feedback principle. The improved tiltmeter features a compact structure and reduced size, which greatly facilitates deployment and installation while significantly enhancing practical applicability. Moreover, it overcomes the drawback of conventional horizontal pendulums—namely, that the scale factor varies with inclination and requires frequent calibration—and thus holds considerable importance for geophysical ground deformation observation.