Tilt-angle monitoring is of extreme importance for the health monitoring of various civil infrastructures such as tunnel, bridges, dams, etc. In addition, it is also one of the key parameters to be monitored in mechanical, instrumentation, robotics, aeronautical engineering applications. Hence, a very accurate, sensitive and compact tilt-monitoring sensor-system capable of resolving lowest possible tilt with a large dynamic range would be of extreme importance. In contrary to electronic tilt sensors, the most striking feature of all optical sensors is its immunity towards electromagnetic interference, which makes them deployable in harsh and high-EMI environments. Significant progress has already been made on all-optical sensing with the manufacturing of in-fiber Bragg grating (FBG), which immediately has become useful in numerous applications over other types of optical fiber sensors and has open up a new domain of research. In most of the proposed techniques a solid mass is used with several optical fibers, with in-built Bragg gratings, connected in orthogonal directions. To make the tilt sensor insensitive to temperature variation, several FBGs are installed within the system and only the difference in response between the FBGs are considered for calculation of tilt. This nullifies the effect of temperature on the FBG. There are also FBG based tilt sensors which are sensitive to temperature and therefore they can be used as temperature sensors as well. This paper aims to review the techniques of implementation of tilt sensors as published by the research community and to compare their relative performance.
Fiber Bragg Grating, Tilt Sensor, Pendulum, Weight Mass
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