Systems and methods for transitioning to higher order degree-of-freedom tracking

A device comprising:

• an inertial measurement unit (IMU) configured to track an orientation of the device;
• a magnetometer configured to track a position of the device with respect to a magnetic tracking volume defined by at least one magnet;
• and
• a tracking subsystem configured to:
• track, using a low-order degree-of-freedom (DOF) mode, the orientation of the device based on input from the IMU when the device is not detected within the magnetic tracking volume;
• determine, using the magnetometer, that the device has entered the magnetic tracking volume by:
• determining a confidence magnitude based on a magnitude of the magnetic field and at least one reference magnitude;
• determining a confidence dip angle based on a speed of change of a dip angle of the magnetic field with respect to a reference horizontal plane and at least one reference dip angle variance;
• determining a combined confidence value based on the confidence magnitude and the confidence dip angle;
• and
• determining that the device has entered the magnetic tracking volume when the combined confidence value satisfies a combined confidence threshold based on a running average of combined confidence values;
• in response to determining that the device has entered the magnetic tracking volume, transition from the low-order DOF mode to a high-order DOF mode that tracks a higher number of DOFs than the low-order DOF mode;
• and
• track, using the high-order DOF mode, the position and orientation of the device based on input from both the IMU and the magnetometer.

A system comprising:

• at least one magnet defining a magnetic tracking volume;
• a device comprising:
• an inertial measurement unit (IMU) configured to track an orientation of the device;
• and
• a magnetometer configured to track a position of the device with respect to the magnetic tracking volume;
• and
• a processing system configured to:
• track, using a low-order degree-of-freedom (DOF) mode, the orientation of the device based on input from the IMU when the device is not detected within the magnetic tracking volume;
• determine, using the magnetometer, that the device has entered the magnetic tracking volume by:
• determining a confidence magnitude based on a magnitude of the magnetic field and at least one reference magnitude;
• determining a confidence dip angle based on a speed of change of a dip angle of the magnetic field with respect to a reference horizontal plane and at least one reference dip angle variance;
• determining a combined confidence value based on the confidence magnitude and the confidence dip angle;
• and
• determining that the device has entered the magnetic tracking volume when the combined confidence value satisfies a combined confidence threshold based on a running average of combined confidence values;
• in response to determining that the device has entered the magnetic tracking volume, transition from the low-order DOF mode to a high-order DOF mode that tracks a higher number of DOFs than the low-order DOF mode;
• and
• track, using the high-order DOF mode, the position and orientation of the device based on input from both the IMU and the magnetometer.