High stability magnetic field compensation method based on ACAC-DOB

Magnetocardiography (MCG) measurement technology is a rapidly developing biomagnetic detection technology in the field of cardiac function imaging. However, its sensitivity to weak magnetic fields from the heart makes it susceptible to disturbances, necessitating a high-precision and stable environment due to stringent signal-to-noise ratio requirements. The existing combination of passive shielding and active compensation is hampered by the inaccuracies of the magnetic shielding room model. A high-stability magnetic field compensation method based on an all-coefficient adaptive control combined with a disturbance observer (ACAC-DOB) is introduced in this article. ACAC acquires the high-order characteristic parameters of the system using recursive least squares on a characteristic model, even in the absence of an accurate model, while DOB detects external disturbances. Experimental results demonstrate that ACAC-DOB can maintain stable control of the magnetic field with an accuracy that is 52.5% higher than that of PID, particularly when the model undergoes changes. Within the frequency range of 1–15 Hz, ACAC-DOB surpasses both ACAC, effectively compensating for external disturbances to within 20 pT and creating a low-noise environment for MCG, thereby enhancing signal-to-noise ratios.