Design of velocity sensor for robotic fish based on fiber Bragg grating

The artificial lateral lines of robotic fish (a kind of underwater unmanned vehicle) have been studied extensively, but mostly based on pressure measurements. Based on fiber Bragg grating, a kind of sensor for artificial lateral line of robotic fish is proposed in this paper. This sensor structure is sensitive to flow velocity. The sensor adopts the target-type structure, and the target is the impacted end of the water flow, so the target arm is deformed. The strain of the target arm is measured by the fiber Bragg grating, so as to reflect the impact of water flow at different flow velocities on the target. The experimental data show that there is an obvious linear relationship between the central wavelength offset and the square of the velocity. Our work demonstrates the feasibility of this sensor structure for velocity measurements.