A novel vibration-level-adjustment strategy for ultralow-frequency vibration calibration based on frequency-shifted method

Aimed at the time-consuming process of an ultralow-frequency vibration calibration, a strategy of rapid vibration-level-adjustment for ultralow-frequency vibration exciters is put forward. First, an ultralow-frequency vibration exciter system based on a displacement feedback control technique is analyzed, whose frequency response function between its input voltage and output displacement is established and calculated based on MATLAB. It is found that the output displacement of the system is only dependent on the input voltage rather than the input signal frequency. Then, a novel rapid vibration-level-adjustment strategy on the basis of the frequency-shifted method is proposed, whose process is that the vibration exciter is first adjusted to the target vibration level at a higher pre-adjustment frequency and then the input signal frequency is gradually decreased from the pre-adjustment frequency to the target ultralow frequency. The method is applied in an ultralow-frequency vibration automatic calibration system. The experimental results indicate that the new strategy can obviously reduce the time of the vibration-level adjustment of ultralow-frequency vibration exciters, and improve the efficiency of the calibration system. The study is helpful for the widespread use of ultralow-frequency vibration calibration.