An Active Positive Stiffness Elastic Suspension Method Based on Absolute Linear Scale

Abstract

An active positive stiffness elastic suspension (APSE-suspension) method is proposed to replace the mechanical elastic suspension device for the precision generation of long stroke standard vibration waveforms so as to meet the requirement of low frequency even ultra-low frequency vibration calibration. The absolute linear scale reading corresponding to the physical zero point of the open-loop vibration exciter is taken as the zero point, the absolute linear scale is used to detect the displacement of the moving part of the vibration exciter relative to the zero point, the displacement signal is amplified by the proportional element, the standard sinusoidal signal outputted by the signal generator is subjected to a difference operation, and the deviation signal is driven by the power amplifier to drive the vibration exciter. The APSE-suspension method produces restoring Lorentz force proportional to vibration displacement and achieves the character of positive stiffness. Experimental results show that the harmonic distortion of displacement waveform of a stroke of 1.2 m is 0.05% after the vibration exciter reaches the steady state.