Fiber optic jerk sensor

Abstract

Jerk is directly related to a physical mutation process of structural damage and human comfort. A fiber optic jerk sensor (FOJS) based on a fiber optic differentiating Mach–Zehnder interferometer is proposed. It can directly measure jerk by demodulating the phase of interference light, which avoids the high-frequency noise interference caused by differentiating the acceleration. The sensing theory and sensor design are given in detail. The experimental and theoretical results agree, demonstrating that the FOJS has a high sensitivity, an ultralow phase noise floor, a wide measuring range, and good linearity. The impact test shows that the FOJS can directly measure jerk and has good consistency with a standard piezoelectric accelerometer. The FOJS has potential applications in earthquake engineering, comfort evaluations, and railway design. This is the first time that directly measuring jerk with an optical sensor is reported.

A Developed Jerk Sensor for Seismic Vibration Measurements: Modeling, Simulation and Experimental Verification

“…The jerk sensitivity (S j ) was obtained by dividing the acceleration sensitivity (S a ) by the input frequency (ω i ) as in Equation (24). The input jerk (j (t) ) was calculated by dividing the angular velocity (Ω tip ) by the jerk sensitivity (S j ) as in Equation (25).…”

“…For calibration, the jerk sensor was subjected to 40 input accelerations in the range of 0.1~1.2 (G). The input accelerations were generated at 20, 40, 60, 80 and 100% torque at each frequency of 5,10,15,20,25,30,35 and 40 (Hz). Then, the experimental calibration curve of the L-35 jerk sensor was constructed by plotting the output gyroscope voltage versus the input jerk for all the 40 input signals recorded in the frequency range of 5~40 (Hz).…”

“…Manabe et al [ 23 , 24 ] proposed a servo-type jerk sensor based on controlling the zero position of a pendulum through velocity feedback control (i.e., PI compensator), which auto corrects the position, enhances stability and reduces oscillation. Li et al [ 25 ] proposed a direct method for measuring the jerk using a fiber optic jerk sensor (FOJS) based on a differentiating Mach–Zehnder interferometer. If the sensing probe detects a jerk signal, the fiber winding on the probe stretches and modulates the phase of the interferometer.…”

Equivalent phase noise analysis in broadband source sensing system using a 3×3 coupler

“…Fiber optic sensing system with a broadband source, which does not need to consider frequency noise and drastically reduces coherence-related noises and drifts, has excellent application potential. Examples include broadband source-driven fiber optic gyros [1], fiber optic jerk sensor [2], and fiber optic strain rate sensor [3]. For the broadband source sensing system with a 3×3 coupler, the relationship of system intensity noise converted into the phase noise floor depends on the demodulation algorithm and 3×3 coupler performance.…”

Fiber optic sensors for seismic wave detection

“…Fiber optic sensors (FOSs), with the advantages of all optical sensing, anti-electromagnetic interference, and long-distance transmission, have been used in seismic wave detection. According to the different requirements in seismic wave detection, FOSs for detecting the different physical parameters have been developed, such as fiber optic strain sensors for crustal deformation observation [1,2], fiber optic seismometers for earthquake monitoring [3,4], and fiber optic jerk sensor for earthquake engineering [5].…”