A magnetically levitated platform with multi-directional quasi-zero stiffness for low-frequency vibration protection

Protective structures are essential for precision instruments like control moment gyros (CMGs) in remote sensing satellites, which require effective three-directional vibration isolation for high agility. This paper introduces an innovative magnetic levitation platform (MLP) for vibration isolation, featuring multi-directional quasi-zero stiffness (QZS) characteristics. The MLP incorporates three identical magnetic springs that convert x/y/z vibrations into vertical ones. These magnetic springs utilize a constant magnetic force generated by a customized magnetic field distortion, differing from traditional systems that rely on positive and negative stiffness elements, which are complex and have limited working strokes. The QZS mechanism of the magnetic spring is demonstrated through magnetic field simulations, followed by structural modeling of the MLP to identify the optimal operating region. Static properties in orthogonal directions and coupling planes are derived and visualized based on potential energy. A dimensionless dynamic model of the orthogonal system is established as a Duffing oscillator, and the effects of damping on nonlinear jumping phenomena are analyzed using transmissibility and energy diagrams. The influence of vibration amplitudes on abnormal dynamic responses (displacement mutations) is explored through bifurcation analysis to assist excitation selection. Experimental results show that the initial vibration isolation frequency is 2.3 Hz in the z direction and 4.3 Hz in the x and y directions, demonstrating the MLP’s capability for low-frequency vibration isolation.