A High-Sensitivity 3-D Displacement Sensor for Deformation Monitoring of Rubber Bearing

Rubber bearings are critical components of base-isolated structures; therefore, it is essential to monitor their deformation states. Current rubber bearing deformation monitoring requires three displacement sensors to track triaxial displacements. This method introduces errors in suppressing off-target displacement interferences, which reduces measurement accuracy. In addition, the simultaneous requirements for a wide measurement range and high sensor sensitivity are mutually restrictive in design. To address the problem, an L-shaped lever structure cantilever-beam 3-D displacement sensor was proposed. A rotational mechanism equipped with an angular sensor is designed at the bottom of the sensor housing, allowing for the acquisition of 3-D displacement information through vector decomposition calculations based on displacement and angle data monitored by a single sensor. This approach mitigates the adverse effects of monitoring accuracy by using multiple sensors. Utilizing its amplification principle, an L-shaped lever amplifies the monitored displacement. It transfers it to the cantilever beam, thereby increasing the surface bending strain of the beam and enhancing sensitivity. The experimental results show that the proposed sensors exhibit a high sensitivity of 50.28 mV/mm in the 0–120 mm range while achieving a high accuracy of 0.49%F.S. And the 3-D spatial displacement measurement error was less than 2 mm. The dynamic displacement measurement error was less than 0.4 mm. The 3-D displacement sensor studied in this study meets the requirements for the sensitivity and accuracy of rubber bearings.