Temperature compensation techniques for high-precision surface displacement sensors based on optical linear encoders

Abstract

This study investigates a temperature compensation method for an optical displacement sensor—a high-precision surface displacement measurement device based on an optical linear encoder—used for continuous monitoring of bridge surface displacement. A key challenge in such applications is the influence of the sensor’s own thermal expansion on measurement accuracy. Traditionally, optical displacement sensors have been employed primarily for monitoring transient responses induced by traffic live loads passing over bridges. In this research, a cut-out slab specimen at Nagaoka National College of Technology was utilized to validate the proposed compensation approach. Measurement data from the sensor were corrected using its experimentally determined thermal expansion coefficient, and the corrected values were found to be consistent with the thermal expansion coefficient of concrete. These findings demonstrate that optical displacement sensors can be effectively applied not only for detecting transient responses to overloaded vehicles but also for continuous structural health monitoring in bridge maintenance.