Linearization of Magnetic Shielding Room Model based on Second-order Variable Phaser

The measurement of magnetocardiography (MCG) and magnetoencephalography (MEG) has become a research hotspot, which requires an extremely weak magnetic field environment usually obtained by combining active magnetic compensation (AMC) technology with magnetic shielding room (MSR). However, the MSR model is nonlinear due to factors such as material characteristics and geometric structure, which limits the development of external AMC systems. This article proposes a linearization method for the MSR model based on a second-order variable phaser. By transforming the nonlinear problem into an input-output phase delay problem and adding a variable phaser, the input-output characteristics of the MSR are linearized. Simulation and experimental results verify the effectiveness of the method, which can improve the linearity of the MSR model and the control accuracy of the magnetic field in the AMC system, providing a new solution for the development of external AMC systems for MSR.