| Seismometers are important instruments for building a digital seismic observation network and implementing seismic scientific investigations.Apart from the field of earthquakes,they are also widely used in other industries such as major building safety assessments.The maintenance of the seismometer is the key to ensure the reliability of the observation data,and the frequency spectrum of the seismic wave usually needs to be corrected by the transfer function of the seismometer.Therefore,the real-time calibration of the seismometer is required.Relevant technicians need to learn the working principle of seismometers and the calibration technology of seismometers through training.Modern feedback seismometers are high-sensitivity vibration measuring instruments of mechatronics,generally using force balance feedback technology.It involves various technologies such as machinery,electronics,and automatic control.The development of seismometers tends to be integrated,miniaturized and intelligent,which brings greater convenience and higher observation accuracy to engineering applications,but its airtight structure is not suitable for teaching,training and laboratory learning.It is difficult to achieve mastery through classroom teaching alone,and demonstration teaching has little effect.New sensing technologies are difficult to inherit.In addition,improving the public-oriented popular science display method for seismometers is conducive to promoting the formation of a socialized system of earthquake prevention and disaster reduction science popularized by "government promotion,departmental collaboration,and social participation".For the needs of experiment,teaching and popular science,this paper developed an experimental multi-modal feedback seismometer with multiple working modes.It takes experimental training as its primary purpose,can carry out laboratory teaching,and is suitable for popular science demonstrations in public places.The seismometer supports differential capacitance displacement energy exchange and moving coil energy exchange.Its structure is visualized,and the mechanical components and modular circuits can be quickly combined,switched or replaced,so as to realize the open-loop mode,force balance feedback accelerometer mode,force balance feedback broadband seismometer mode and dynamic loop energy exchange feedback seismometer mode for different frequency bands of seismic information.The experimental multi-mode feedback seismometer can be used as a research and Development Experimental Platform for seismometer research and development and parameter specification measurement research,as well as a test platform for various seismometer related research such as self-test technology of feedback seismometer.In this paper,the scheme design of the experimental multi-modal feedback seismometer is completed,and the feedback seismometer experimental device is equipped.Then,the feedback circuit experiments and parameter optimization of the moving coil transducer feedback seismometer,the displacement transducer feedback seismometer,and the force balance accelerometer were carried out,and the pulse calibration and sine wave calibration test experiments were carried out.Then,a sensitivity self-test method is proposed,and the simulation calculation and experimental verification are carried out.The research has a good demonstration effect on the teaching and training of feedback seismometer,and provides a feasible method for the on-line sensitivity test of seismometer.In the feedback circuit experiment,the natural vibration period and damping of the mechanical pendulum are calibrated through the open-loop mode.Through modular combination and circuit parameter configuration,the force balance feedback accelerometer with observation frequency band of DC-18 Hz,the force balance feedback broadband seismometer with observation frequency band of 30s-10 Hz,50s-40 Hz and 100s-40 Hz,and the dynamic coil energy exchange feedback seismometer with observation frequency band of 10s-10 Hz are realized.Then the experimental work of feedback circuit is summarized,and the shortcomings and improvement measures in the experimental research are analyzed.Based on the analysis of the existing seismometer calibration technology and the feasibility of the self-test implementation of modern feedback seismometers,this paper puts forward a self-test scheme for the E value of the seismometer coil conversion constant,and takes the experimental multimodal feedback seismometer as the experimental platform to test the E value,which proves the practical feasibility of the scheme.To further analyze the lack of existing seismometer sensitivity detection technology,this paper proposes a sensitivity self-test method which is easy to operate,and in the follow-up,the practical experiment of this method proves the feasibility of the scheme.The sensitivity self-test method can be realized through the relay and the calibration device assembled in the feedback seismometer,without the help of manual assistance,which is conducive to promoting the remote automatic calibration technology of seismometer sensitivity. |
