Design And Development Of A Low Frequency Standard Vibration Calibration System

Low frequency vibration sensors are widely used in aerospace,earthquake,civil engineering and other engineering fields,and sensors usually need to be calibrated periodically before or after use.At present,the vibration sensor calibration usually uses the electric vibration table to calibrate,which generally has the defects of short stroke,narrow calibration frequency range,and high distortion in low frequency band.In order to solve the above problems,the optimization design of magnetic circuit,guide rail and elastic support elements is usually adopted at home and abroad to improve the control performance.In this paper,the linear motor is used as the actuator,and the precise grating displacement sensor is used as the feedback input.A new low-frequency calibration device based on the working principle of linear motor is developed,the low-frequency vibration control algorithm is optimized,and the adaptive harmonic suppression strategy is proposed for the control of waveform distortion.In this paper,the low-frequency standard vibration calibration system is studied and analyzed.The theoretical analysis and mathematical modeling of motor drive,feedback control,data acquisition,amplitude and phase measurement,harmonic suppression and other modules are carried out.Through simulation analysis and calculation,the feasible scheme and corresponding design parameters are determined.Secondly,in view of the shortcomings of low frequency vibration calibration,such as poor amplitude recognition accuracy and long measurement time,this paper proposes to use multi sampling rate method to track and filter,and realize the accurate measurement of signal amplitude and phase by self-adaptive selection of sampling rate during calibration,so as to improve the system calibration speed and control accuracy.Aiming at the problem of high distortion in low-frequency standard vibration calibration system,this paper studies the working principle of linear motor,analyzes the influencing factors of waveform distortion caused by linear motor,and proposes and realizes adaptive harmonic suppression strategy to reduce the harmonic component of acceleration output waveform.Firstly,the transfer function of the system is identified by the amplitude measurement technology,and then the harmonic components with adjustable weight vectors are injected into the system by the least mean square algorithm.Finally,the distortion of the whole system meets the design requirements.In this paper,the low frequency calibration system is analyzed theoretically and simulated,and the hardware and software of the vibration control calibration system are designed.The amplitude and phase control technology and adaptive harmonic suppression strategy are verified on the platform.At last,a comparative test of calibration of multi-sensor is carried out.The test results show that the low-frequency vibration calibration system studied in this paper has the advantages of wide calibration frequency range(0.01 Hz ? 200Hz),low waveform distortion,long stroke,etc.,and meets the requirements of vibration and shock sensor calibration method(GB /T20485.21-2007)and low-frequency vibration sensor calibration specification(NB/T42120-2017).