An Electromagnetic Negative Stiffness Spring With High Response Speed and Its Semiactive Vibration Control

Electromagnetic negative stiffness springs have been widely used in low-frequency vibration isolation because they can achieve high-static-low-dynamic stiffness (HSLDS) and stiffness control, which are necessary to improve the accuracy of industrial processing and measurement. However, the slow response of these springs limits their performance. In this study, by analyzing the stiffness characteristics of each coil turn, an arrangement method for multiple magnets and coils is proposed to improve the efficiency of stiffness generation, so as to improve the response speed without compromising the stiffness tunable range. The stiffness tunable range of the designed fast response electromagnetic negative stiffness spring is
$\boldsymbol{\pm }$
6650 N/m, and the response time is reduced to 0.5 ms. A semiactive HSLDS isolator based on the fast response electromagnetic negative stiffness spring was established, and a semiactive stiffness control algorithm based on a linear quadratic regulator was designed. The experimental results show that the introduction of passive negative stiffness can expand the isolation frequency band, and the introduction of semiactive control can further expand the frequency band and decrease the resonance peak. Moreover, compared with traditional control methods, semiactive control with negative electromagnetic stiffness can obtain a wider frequency band and higher vibration isolation performance.