Automatic Shielding-Shimming Magnetic Field Compensator for Excluded Volume Applications

Abstract

We discuss the problem of automatic magnetic field compensation within an excluded volume where the magnetic field cannot be sensed in a direct way. Both magnetic field spatial average (shielding) and first order orthogonal gradients (shimming) are considered. The active shielding-shimming compensator is based on a multiple-input multiple-output controller driving a specifically designed coil-set. The magnetic field and its gradients are calculated from the readings of ten hall sensors located outside the exclusion volume.