Research On Some Problems For Dynamic Measurement Technology Of Ultra-low Frequency Vibration Sensors

Based on the present research status for dynamic characteristics measurement of vibration sensors and the particularities for dynamic characteristics measurement of ultra-low frequency vibration sensors,some problems for dynamic characteristics measurement technology of ultra-low frequency vibration sensors were researched.In chapter 1,the backgrounds,significance and main contents of the thesis were presented.First,the vibration sensors and its dynamic characteristics were introduced.Secondly,dynamic calibration technology and dynamic range measurement technology of vibration sensors were presented.Thirdly,the present research status for dynamic characteristics measurement of vibration sensors at home and abroad were introduced.Finally,the particularities for dynamic characteristics measurement of ultra-low frequency vibration sensors were analyzed,and the aim and content of the thesis were put forward.In chapter 2,the fast adjustment method for the ultra-low frequency vibration level was studied.First,the existing methods and problems of the vibration level adjustment for the ultra-low frequency vibrator system were analyzed.Secondly,a fast estimation method for the amplitude of the ultra-low frequency sinusoidal signal was analyzed,and the simulation analysis was carried out.Then,a fast adjustment method of overlapping and residual period for the ultra-low frequency vibration level was proposed based on the proposed fast estimation method.Finally,the related software for the fast vibration level adjustment in an ultra-low frequency vibration calibration device was designed.In chapter 3,the compensation method of the guide rail irregularity was designed for dynamic characteristics calibration of very-broadband seismometers.First,the guide rail irregularity in the vibrator was studied.Then,a velocity type very-broadband seismometers was taken as an example,and the influence of guide rail irregularity on the calibration results of this seismometer was analyzed.Finally,the compensation method was proposed to eliminate the influence,and the software for the compensation of guide rail irregularity was designed.In chapter 4,the dynamic range measurement of ultra-low frequency vibration sensors was studied.First,the sources of self-noise of ultra-low frequency vibration sensors were analyzed,and the questions of self-noise measurement for vibration sensors were studied.Then,the key technologies on the Sleeman's three channels method,such as the data preprocessing,the power spectrum density estimation method,the conversion of power spectrum density to amplitude spectrum,the influence of acquisition equipment noise,etc.,were researched.Finally,the measurement software of dynamic range for ultra-low frequency vibration sensors was developed.In chapter 5,the experimental study on some problems for dynamic characteristics measurement technology of ultra-low frequency vibration sensors was carried out.First,a comparative study on the existing methods and the fast adjustment method of overlapping and residual period was implemented,whose results showed that the adjustment speed of the proposed method in the thesis was the best.Then,the irregularity compensation method for the guide rail in the vibrator was used to compensate the amplitude-frequency characteristics and amplitude linearity of very-broadband seismometers,whose results showed that the compensation method could reduce the influence of guide rail irregularity in the dynamic characteristics calibration of very broadband seismometers.Finally,the experimental study on the dynamic range measurement of MEMS acceleration transducers was carried out,whose results show that the software could accurately measure the dynamic range of ultra-low frequency vibration sensors.In chapter 6,the results of this paper were summarized,and the further research work was prospected.