Experimental Investigation of Time-Delayed Control for Enhanced Performance in a High-Static-Low-Dynamic-Stiffness Vibration Isolation System

This article explores the dynamic effects of implementing time-delayed feedback in a passive high-static-low-dynamic-stiffness (HSLDS) isolator and its potential to enhance low-frequency isolation performance. An inherent delay of 7-16 ms and a filter delay of 53 ms are identified to demonstrate that the active feedback in HSLDS systems intrinsically involves delay effects. We then clarify the effects of delayed acceleration feedback on the stability and steady-state response of the isolator. Finally, we develop an optimization strategy employing the Broyden-Fletcher-Goldfarb-Shanno algorithm to improve the isolation performance while ensuring the stability margin. Experimental results indicate that optimizing the feedback parameters enhances the isolation by over 50% and reduces the initial isolation frequency from 8.48 to 6.2 Hz. These findings prove that the feedback delay, when effectively harnessed, can serve as a valuable control resource, particularly when combined with the negative stiffness structure to maximize low-frequency vibration suppression effect.