A Localization System Utilizing Maxwell Coil Gradient Magnetic Fields Integrated With Inertial Measurement Unit for Surgical Instrument

The implementation of traditional surgical procedures heavily relies on the surgeon’s experience. During the operation, surgical instruments are often obscured by other anatomical structures, hindering effective surgical navigation. This makes it challenging for surgeons to accurately track and determine the positions of surgical instruments. Therefore, it is crucial to develop a positioning system capable of providing precise coordinates of surgical instruments even when the view field is obstructed. We propose a magnetic field fingerprint positioning (MFP) method that combines a triaxial magnetic sensor with an inertial measurement unit (IMU) called MFP(N, M) + IMU, where N and M represent the division of a cubic space into ${N}^{\,{3}{M}}$ smaller cubes. The MFP ${(N, M)} +$ IMU algorithm can accurately locate surgical instruments even in situations of view field obstruction. Using the pose information measured by the IMU sensor to compensate for the angular components of the magnetic induction intensity measured by the triaxial magnetic sensor, the magnetic localization algorithm can function normally even when the sensor is in different poses. This method achieves six-degree-of-freedom (6-DOF) localization within a gradient uniform magnetic field and results in good localization accuracy. In practical experiments with the prototype system, the grid localization error of the MFP(N, M) + IMU algorithm is less than 1.5 mm with ${N} =16$ and ${M} =2$ . Compared with the Polhemus Liberty, the positioning system proposed in this article improves grid positioning accuracy by approximately 48.9%, and compared with the Northern Digital Inc., (NDI) Aurora, it improves by approximately 56.8%, with better performance than the existing localization methods.