Beneficial performance of a quasi-zero-stiffness vibration isolator with displacement-velocity feedback control

Abstract A displacement-velocity feedback control method is proposed to enhance the isolation performance of a quasi-zero-stiffness vibration isolator (QZS-VI). Time delay is considered in the controlled QZS-VI system. First, the steady-state solutions are obtained using the averaging method and further validated by a numerical method. The jump phenomenon and frequency island phenomenon could occur, and the stability analysis is implemented. Then, the effects of time delay and feedback gain on the frequency response and stability of solutions are analyzed in detail. And then, the force transmissibility is defined to evaluate the isolation performance of the controlled QZS-VI system. The results show that the time delay mainly affects the stability of the controlled system and has a weak influence on the isolation performance. The proposed displacement-velocity feedback control method can suppress the vibration in the resonant region effectively without affecting the performance in the isolation region. Finally, the vibration control effect is illustrated by the concept of an equivalent damping ratio.