Enhanced Active Magnetic Shielding Based on High-order Extended State Observer

Active magnetic shielding (AMS) plays a pivotal role in enabling ultra-weak magnetic field measurements. However, existing techniques often fall short when confronted with complex and time-varying magnetic disturbances. In this work, we propose an enhanced AMS approach based on a high-order extended state observer (HESO), designed to address these limitations. First, a precise dynamic model of the AMS system is established. Next, both the conventional linear extended state observer (LESO) and the proposed HESO are developed. To optimize the performance of HESO, two tuning strategies are investigated: a bandwidth-based method and a Chebyshev filter-based method that improves frequency selectivity and noise suppression. Finally, extensive simulation and experimental results confirm that the proposed HESO-based AMS framework significantly improves disturbance rejection in the presence of time-varying magnetic interference, offering a more robust solution for high-precision magnetically shielded environments.