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 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 2D finite element analysis. Experimental results show that the sensor has a natural frequency for about 9.87 Hz; its sensitivity is 144.99 pm/g 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 good repeatability of less than 1.8%. Moreover, its transverse crosstalk, dynamic range, 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.