A widely uniform and highly ambient robust DC magnetic field generator for precise motion sensors

Abstract

A widely uniform and highly ambient robust DC magnetic field generator for precise motion sensors using inertial measurement units (IMUs) is newly proposed in this paper. Chronic problems such as low uniformity of magnetic field and geomagnetic disturbance of conventional Helmholtz, Merritt, Rubens, Lee-Whiting, and Tetra coils can be significantly mitigated by the proposed uniform DC magnetic field generator (UFG). Different from the previous air coils, the proposed UFG adopts a core-cage so that a strong and uniform DC magnetic field distribution can be generated inside the cage and that the UFG may be quite magnetically robust to ambient changes such as geomagnetic field and ferromagnetic objects. Design procedures for the UFG are fully established. Detailed designs of the UFG for magnetic field generation, enhancing uniformity, and geomagnetic cancellation are provided. Experiments for a prototype UFG of 30 cm × 30 cm × 30 cm size showed that the geomagnetic field inside the UFG was significantly attenuated by − 21 dB while the DC magnetic field uniformity (< 10°) was achieved over 81 % of the total volume of 27,000 cm3.