Random-rotational angle sensor based on fiber Bragg gratings

A novel rotational-position sensor consists of two FBGs glued axially on a capillary surface and driven bent by attraction of a magnetic disk, which accurately detects random rotation angle in both static and dynamic conditions.

I. Introduction

Rotational-position detecting technique plays an important role in many fields [1]–[3] of applications, such as flow-control valve in fluid supply systems, rudder-control system on shipboard, flap-control on airplanes, anemoscope in meteorological stations and so forth. Fiber Bragg gratings (FBGs) have been widely used as sensors for the measurement of temperature, strain, pressure, force, and even tilt angle. FBG has many intrinsic advantages including electromagnetic immunity, great multiplexing capability, exemption from electric or water insulation requirements, and intrinsic wavelength-based encoding characteristics over others. Therefore FBG-based sensor has been made attractive for a number of industrial detecting applications. This paper proposed a novel, high-resolution, simple-structure, and low-cost rotational position sensor using a pair of fiber Bragg gratings for rotational angle detection and angle demodulation. Rotational position measurement accuracy and resolution were demonstrated as well. Due to the absence of electrical signals, this sensor can even work satisfactorily under adverse environments.