Disturbance Suppression Method for Three-Axis Active Magnetic Compensation System Based on ISMC-LESO

The three-axis active magnetic compensation (TAMC) system is widely used to suppress environmental magnetic disturbances in magnetically shielded room (MSR), enabling stable ultra-weak magnetic measurements with reduced cost. Nonlinear, time-varying, and coupled behaviors induced by the shielding material’s magnetic properties pose challenges to accurate modeling and disturbance suppression. A composite control strategy combining linear extended state observer (LESO) with integral sliding mode control (ISMC) is proposed. The LESO is implemented for each axis to provide real-time estimates of external disturbances, model uncertainties, and inter-axis coupling. Based on the LESO estimates, the ISMCs are designed to enhance robustness against parameter variations and nonlinearity while compensating for disturbances. Experimental results on a TAMC platform demonstrate that the proposed method effectively suppresses magnetic disturbances, which significantly reduces magnetic fluctuations inside the MSR and ensuring reliable conditions for high-precision biomagnetic measurements.