Design And Research Of Rotational Seismometer Based On Electrochemical Transducers

With the further development of seismology,the measurement of rotational ground motion has been developed as a new field of seismology.The analysis of rotational motion is helpful not only to seismic inversion and determination of epicentral distance,but also to engineer application.High-precision instruments are indispensable to the observation of rotating components.High-sensitivity,high-precision,wide-band and low-cost are the future development focus of rotational seismometers.A rotational seismometer based on electrochemical transducers has been designed in this paper,which combines the electrochemical transducer technique with the jet gyroscope,and overcomes the disadvantages of low conversion efficiency and delayed response of the jet gyroscope.In addition,the rotational seismometer based on electrochemical transducers have the strengths of large dynamic range,high sensitivity and good low-frequency performance,which make them suitable for earthquake monitoring in low-frequency.I have not only researched and analyzed the working principle of the rotational seismometer,but designed the overall scheme of the external circuit and prototype experiments too.First of all,the mechanical structure of the rotational seismometer is designed based on the structure of the traditional jet gyroscope,and its working principle and noise source is deeply studied.The mathematical model of the seismometer is deduced,which provides the theoretical basis for the simulation of the reaction chamber of rotational seismometer.Secondly,the 2D simulation model of the rotational seismometer's reaction chamber is established by the COMSOL Multiphysics software,which contacts the coupling of electrochemical field and the fluid field.The relationships between jet velocity or external angular rate and the output signal are simulated.Moreover,the simulation results of electrochemical rotational seismometer are analyzed in three aspects:time-domain,frequency-domain and index,which is helpful to the design of experiment scheme.Thirdly,the signal processing circuit and power circuit are designed for the electrochemical transducers.The output signal of the seismometer is further improved,and the signal-to-noise ratio of the system.Finally,the experimental scheme and steps of the seismometer's prototype are designed,the relevant experiments are completed on the vibration test bench,and the output response curve of the prototype is drawn.Comparing with the simulation results,the work cut-off frequency is consistent with the simulation results.The reasons for the deviation between the experimental results and the simulation results are analyzed.The experimental results show that the sensitivity of the prototype is 118 m V/°/s,the signal-to-noise ratio is about 43 d B and the minimum resolution is 2.2×10^-3°/at 0.1 Hz,which achieve the design objectives.