Realization of low-distortion ultra-low-frequency vibration based on feedback control technology

An effective system used to produce the displacement associated with low-distortion sine-wave is studied. Firstly, the nonlinear dynamic characteristics of vibration tables are analyzed and the distorted displacement waveform is obtained with the method of simulation. Secondly, a controlling method based on the technology of displacement feedback is devised, and the method is proved to be effective by simulation. Finally, a kind of vibration table system that could output low-distortion displacement is developed. Frequencies as low as 0.01 Hz can be generated with the displacement distortion less than 0.3% in the vertical table and less than 0.6% in the horizontal table. The system meets and exceeds standards set by the department of metrology.