Embedding intelligent excitation adaptability for resonance-suppressed QZS vibration isolation

Quasi-zero stiffness (QZS) vibration isolation provides a practical solution to the long-standing difficulty of low-frequency vibration isolation in conventional systems, but its inability to eliminate resonance renders it sensitive to excitation variability and potential dynamic amplification. This work proposes an intelligent QZS vibration isolator (IQZS-VI) that achieves both broadband vibration isolation and resonance suppression via an excitation-adaptive mechanism. It features two operational modes that can be autonomously switched according to the excitation variation, where one mode has a QZS and the other has a linear positive stiffness (LPS). Operating normally in QZS mode, the system autonomously switches to LPS mode upon detecting the resonance frequency, resulting in a significantly reduced vibration transmissibility. A cam-roller-spring QZS vibration isolator with a stepper motor and skew slider for stiffness switching is designed to achieve the stiffness adjustment, while a fast frequency identification algorithm is embedded. Static and dynamical characterizations are carried out to clarify the relationship between the system performance and the key parameters. Experiments are performed to demonstrate its autonomy and vibration control performance under frequency-variable excitations, during which the developed model is also validated. The results show that the resonance peak decreases by up to 87.5% with the mode switching autonomously completed in approximately 430 ms following frequency identification. Further simulations under multi-frequency excitations are performed, and the results demonstrate the promising applicability of the IQZS-VI under such conditions.