Decoupling and Disturbance Rejection Method for a Three-Axis Active Magnetic Compensation System Based on DESO-DISMC

The three-axis active magnetic compensation system suppresses magnetic field disturbances around a magnetically shielded room for ultra-weak magnetic field measurements. However, coupling among control axes increases the complexity of disturbance suppression. To address this issue, a discrete control method is proposed. A decoupling matrix is designed to transform the system into three independent single-input singleoutput subsystems. For each subsystem, a discrete extended state observer is employed to estimate residual coupling and environmental disturbances online, and a discrete integral sliding mode controller is developed to enhance robustness against parameter variations and uncertainties. Experimental results demonstrate that the proposed method effectively suppresses system coupling and environmental disturbances, stabilizing the magnetic field at the MSR center near the zero-field level and satisfying the requirements for ultra-weak magnetic field measurements.