Fiber-optic amplitude bend direction and magnitude sensor

Abstract

A variant of the implementation of a fiber-optic sensor for the direction and magnitude of the bend is proposed. Unlike existing spectral measuring systems, the solution under consideration involves the use of an amplitude polling technique which makes it possible to increase the speed of the sensor when using simpler and more affordable components. A sensitive element based on special diffraction structures consisting of pairs of chirped fiber Bragg gratings has been studied. The sensing elements are mounted on a tooling — a steel rod subjected to bending. The ability of the sensor to determine the magnitude and direction of bending in the deviation range from 0 to 30 mm was demonstrated with a standard deviation of the measured values from the real values of 0.536 mm. This measurement result is achieved by processing data obtained from three measuring devices and by the neural network with a hidden layer of 10 neurons and the sigmoid as the activation function. The research results are essential for modern monitoring systems. The implementation of the direction and magnitude of the bend sensor in the format of a fiber-optic device allows you to overcome the limitations of piezoelectric sensors, due to high noise immunity and resistance to environmental influences. The proposed technological solution makes it possible to avoid the spectral measurement technique that has become widely used in fiber-optic sensor systems. The use of an amplitude sensor for the magnitude and direction of bending will allow its use in devices where there is a need for precise positioning of control elements or structural components subjected to bending. Also, due to the measurement of the desired bending effect by estimating the optical power of the signal, the design of the sensor does not require the presence of a complex measuring device, and the sensor’s performance can be ensured using a cascade of inexpensive, but at the same time high-speed and durable photodetectors.

Keywords

• fiber bragg grating
• fiber optic sensor
• bend direction and magnitude sensor