Performance analysis of a quasi-zero-stiffness vibration isolator with time-delayed dual feedback control

Aiming at the problem that the isolation performance of the quasi-zero stiffness vibration isolators (QZS-VIs) in the resonant region worsens with the increase in excitation amplitude, a time-delayed dual feedback control method combining cubic displacement feedback and cubic velocity feedback is developed in this paper. First, the force and stiffness characteristics of a QZS-VI containing scissor-like structures are given. Then, the steady-state solutions of the controlled QZS-VI system are obtained using the averaging method, and their stability is analyzed. The effects of feedback parameters on the dynamic response and force transmissibility of the controlled QZS-VI system are investigated. A basis for selecting feedback parameters is given. At last, the vibration control effect of the developed dual feedback control method is illustrated from the point of view of an equivalent damping ratio. The results show that the developed dual feedback control method can effectively suppress vibration in the resonant region without affecting performance in the isolation region. Designing an appropriate time delay can improve the control effect.