Design and control of a variable-stiffness maglev vibration isolation system under broadband excitation

Broadband stochastic vibrations have become a critical bottleneck limiting the measurement accuracy and operational stability of precision equipment in marine engineering and resource exploration. Conventional passive isolation and linear feedback control methods suffer from limited bandwidth and insufficient robustness under low-frequency broadband excitations. To address these challenges, a magnetically levitated vibration isolation system based on adaptive nonsingular terminal sliding mode control (ANTSM-MI) is proposed. The system adopts a symmetric contactless maglev configuration with a dual-armature structure to enhance electromagnetic force output. A nonlinear dynamic model is established, and the electromagnetic force is parameterized as an explicit nonlinear function of current and air gap. An adaptive nonsingular terminal sliding mode controller is developed to ensure finite-time convergence without requiring prior knowledge of disturbance bounds, while avoiding singularity issues. By exploiting electromagnetic nonlinear coupling, the system achieves real-time regulation of equivalent stiffness, enabling a unified realization of high static stiffness and low dynamic stiffness. Results show that the proposed method enables targeted vibration suppression in the dominant energy input band and maintains stable isolation performance over a broadband range. The transmissibility remains below −20 dB within 1–35 Hz without introducing additional resonance peaks. The proposed approach provides a robust solution for vibration isolation under complex stochastic excitations.