Automatically synchronizing a transmitter and receiver in a magnetic tracking system using information from an inertial measurement unit

An automatically synchronizing magnetic tracking system for properly determining a position and orientation of a receiver relative to a transmitter, comprising:

• a transmitter comprising a plurality of source magnetic coils each configured to generate a magnetic field and a transmitter inertial measurement unit (IMU);
• receiver comprising a plurality of sensor magnetic coils configured to sense the magnetic fields and to generate a raw signal matrix (SigMat) representing the position and orientation of the receiver relative to the transmitter and a receiver inertial measurement unit (IMU);
• and
• a processor configured to:
• receive the raw SigMat from the receiver, receiver IMU acceleration data from the receiver, receiver IMU angular velocity data from the receiver, transmitter IMU acceleration data from the transmitter, and transmitter IMU angular velocity data from the transmitter;
• generate a global orientation of the receiver from the receiver IMU acceleration data and the receiver IMU angular velocity data;
• generate a global orientation of the transmitter from the transmitter IMU acceleration data and the transmitter IMU angular velocity data;
• generate a set of rotated SigMats by multiplying the raw SigMat by each of four sync correction matrices;
• generate a set of calibrated, rotated SigMats from the rotated SigMats by applying orthogonalization gain matrices for the receiver sensor magnetic coils and the transmitter source magnetic coils to the rotated SigMats;
• determine a residual error of each of the calibrated, rotated SigMats;
• select the rotated SigMat having a lowest residual error;
• and
• cause the receiver to be synchronized with respect to at least position relative to the transmitter based at least in part on the selected, rotate SigMat having the lower residual error.

A non-transitory computer readable storage medium having embodied thereon instructions for causing a computing device to execute a method of automatically synchronizing a transmitter and a receiver in a magnetic tracking system to properly determine a position and orientation of the receiver relative to the transmitter, the transmitter comprising a plurality of source magnetic coils each configured to generate a magnetic field and a transmitter inertial measurement unit (IMU), and the receiver comprising a plurality of sensor magnetic coils configured to sense the magnetic fields and to generate a raw signal matrix (SigMat) representing the position and orientation of the receiver relative to the transmitter and a receiver inertial measurement unit (IMU), the method comprising:

• receiving the raw SigMat from the receiver, receiver IMU acceleration data from the receiver, receiver IMU angular velocity data from the receiver, transmitter IMU acceleration data from the transmitter, and transmitter IMU angular velocity data from the transmitter;
• generating a global orientation of the receiver from the receiver IMU acceleration data and the receiver IMU angular velocity data;
• generating a global orientation of the transmitter from the transmitter IMU acceleration data and the transmitter IMU angular velocity data;
• generating a set of rotated SigMats by multiplying the raw SigMat by each of four sync correction matrices;
• generating a set of calibrated, rotated SigMats from the rotated SigMats by applying orthogonalization gain matrices for the receiver sensor magnetic coils and the transmitter source magnetic coils to the rotated SigMats;
• determining a residual error of each of the calibrated, rotated SigMats;
• selecting the calibrated, rotated SigMat having a lowest residual error;
• and
• causing the receiver to be synchronized with respect to at least position relative to the transmitter based at least in part on the selected calibrated, rotated SigMat having the lowest residual error.