A Novel Method for Fishing Boat Vibration Sensing Using an FBG-Based Warning Sign Pile Accelerometer

Vibration detection in machine health monitoring, perimeter/boundary monitoring, etc., is a subject of great interest in areas such as mechanics of deep-sea fishing or aquaculture boats, military, seismic exploration, etc. By resizing a warning sign pile (WSP), and adding a low-reflectivity fiber Bragg grating (FBG) vibration detector with a sensitive mass fixed at the right position, an FBG-based WSP accelerometer is proposed. The theoretical study of key steps in the sensing of the new accelerometer was carried out by 2-D finite element analysis. Experimental results show that the sensor has a natural frequency of about 9.87 Hz; its sensitivity is 144.99 and 10.68 pm/g in the low (2–90 Hz) and high (90–615 Hz) frequency range, respectively. The FBG-based WSP accelerometer has a wide working frequency range of 90–615 Hz and a good repeatability of less than 1.8%. Moreover, its transverse crosstalk, dynamic range (DR), natural frequency, and resolution are −28.65 dB, 65.52 dB, 9.87 Hz, and 0.037 g, respectively. Field experiments show that due to its structural advantages, the sensor can detect vibrations coming from all directions. It has a maximum relative error on acceleration measurements via central wavelength shift of 11.9% and an absolute error of less than 6 pm.