Research On The Damping Design And Hybrid Time-delayed Control Of Lever-type Quasi-zero-stiffness Vibration Isolation Systems

With the lightweight and large-scale development of aerospace structures,the slow attenuation rate of low-frequency vibrations and difficulty of control have constrained the accuracy,reliability,and stability of spacecraft.The linear vibration isolation technology has a narrow isolation frequency band,and there is a contradiction between the isolation frequency band and the bearing capacity.Quasi-zero-stiffness isolators(QZS-VIs)can effectively broaden the isolation frequency band without affecting the bearing capacity,and their isolation performance is superior to linear isolators.However,in complex excitation environments,the isolation performance and stability of QZS-VIs will deteriorate.Apart from the nonlinear stiffness mechanism,the isolation frequency band of the isolator can also be expanded by introducing an inertia mechanism.This article conducts research on semi-active damping control and time-delayed active control of a lever-type QZS(L-QZS)isolation system.The article focuses on:1)A lever-type electromagnetic shunt damping method was proposed,and its damping regulation mechanism is revealed.A lever-type electromagnetic shunt damper(L-EMSD)and designed,and two types of L-EMSD structures were obtained.The dynamic theoretical model was established,and the effects of lever on the damping effect of the damper were studied.The optimal parameters of a negative resistance resonant shunt damper were derived based on the Den Hartog fixed point theory.An experimental system was designed to verify the effect of L-EMSD parameters on the vibration isolation performance of lever-type isolators(LVIs).The experimental results show that both negative resistance and lever structure can effectively improve electromagnetic damping force,and the negative resistance resonant shunt damper can improve the damping performance of the LVIs by about 73%.2)A semi-active damping control method for the L-QZS-VI was proposed.A dynamic model for semi-active damping control of a lever-type nonlinear isolation coupling system was established,and the amplitude-frequency response relationship of the system was obtained based on the harmonic balance method.The effect of geometric and electromagnetic parameters on the vibration isolation performance of the L-QZS-VI was studied.The simulation and experimental results indicate that using L-EMSD for semi-active control of nonlinear stiffness can improve the isolation performance of nonlinear isolators and eliminate jumping and chaos phenomena.3)An active vibration isolation method using time-delayed feedback hybrid control is proposed.A hybrid time-delay control dynamic model based on lever-type isolation systems was established,and the optimal time-delay of feedback control was obtained.A variable time-delayed feedforward feedback controller was designed,and the theoretical model of the control system was derived.A semi-physical experimental system based on dSPACE was designed,and the research results showed that time-delayed hybrid control can provide small stiffness effects,but has significant damping effects,and the isolation performance has been improved by 81.6%.4)A dynamic theoretical model of a L-QZS-VI based on time-delay hybrid control has been established.Based on the modified harmonic balance method,the amplitude frequency response relationship of an active vibration isolation system of L-QZS-VI was obtained.An experimental system was designed,and the research results showed that the proposed time-delayed hybrid control can eliminate resonance phenomena,eliminating unstable dynamic behaviors such as jumping and hybrid vibration caused by nonlinear characteristics of the system,and improve the low-frequency vibration isolation performance of the system.This article proposes a damping design and hybrid time-delayed active isolation method for a L-QZS isolation system,and studies the damping amplification effect of the lever on the electromagnetic shunt and the isolation performance of the variable time-delayed hybrid control.The L-EMSD greatly improves the isolation performance of nonlinear isolators and avoids instability caused by system nonlinearity.Hybrid time-delayed control can completely suppress resonance phenomena,effectively suppress large-scale vibration of the system,and eliminate jumping and chaos phenomena caused by nonlinear characteristics of the system.The damping control technology and hybrid time-delayed control technology designed in this article provide new methods for nonlinear vibration isolation.