Integration of Nonlinear-Vibration-Isolation and Actuation: Design and Control

Due to stiffness nonlinearity, the performance of nonlinear vibration isolators is coupled with the applied load and equilibrium position, resulting in performance degradation under mismatched working loads or operating points. Herein, a novel quasi-zero stiffness (QZS) vibration isolator integrating nonlinear-vibration-isolation and actuation (QVI-INA) is proposed and systematically investigated. The QZS is achieved by exploiting an electromagnetic combination structure with tailorable negative stiffness to modulate a membrane spring support with nonlinear positive stiffness. Interestingly, by regulating the interval and value of negative stiffness, the QVI-INA is endowed with independent rated load modulation and equilibrium position modulation. This enables the decoupling of isolation performance from the applied load and equilibrium position, further facilitating the integration of nonlinear-vibration-isolation and actuation (INA). A comprehensive static investigation is conducted to reveal the integration mechanism. To fulfill high-precision trajectory tracking under broadband base excitations, a weak-stiffness output controller is developed based on independent rated load modulation and verified through load actuation simulations. In addition, a comparison between the INA and the integration of linear-vibration-isolation and actuation is performed, confirming the superiority of the INA in reducing the tracking error. Finally, load actuation tests with base excitations are implemented, and the results demonstrate that the QVI-INA can accomplish low-error trajectory tracking thanks to its excellent nonactive vibration isolation performance.