Using Magnetic-Sensor Data to Correct for INS Drift

One or more computer-readable non-transitory storage media embodying software that is operable when executed to:

• access a magnetic-field map of a region, wherein the magnetic-field map comprises a plurality of map points that correspond to locations in the region and are associated with magnetic-field values corresponding to the locations in the region;
• access a trajectory, wherein the trajectory comprises a plurality of trajectory points that correspond to a path and are associated with magnetic-field values measured along the path;
• compare the magnetic-field values associated with the trajectory points with the magnetic-field values associated with the map points;
• based on the comparison, identify one or more of the trajectory points that approximately magnetically coincide with one or more of the map points;
• based on the identification, adjust one or more of the trajectory points to be approximately colocated with one or more of the map points;
• and
• incorporate the trajectory points and the magnetic-field values associated with them as adjusted into the magnetic-field map.

A system comprising:

• one or more processors;
• and
• one or more computer-readable non-transitory storage media coupled to one or more of the processors and comprising instructions operable when executed by one or more of the processors to cause the system to:
• access a magnetic-field map of a region, wherein the magnetic-field map comprises a plurality of map points that correspond to locations in the region and are associated with magnetic-field values corresponding to the locations in the region;
• access a trajectory, wherein the trajectory comprises a plurality of trajectory points that correspond to a path and are associated with magnetic-field values measured along the path;
• compare the magnetic-field values associated with the trajectory points with the magnetic-field values associated with the map points;
• based on the comparison, identify one or more of the trajectory points that approximately magnetically coincide with one or more of the map points;
• based on the identification, adjust one or more of the trajectory points to be approximately colocated with one or more of the map points;
• and
• incorporate the trajectory points and the magnetic-field values associated with them as adjusted into the magnetic-field map.

A system comprising:

• means for accessing a magnetic-field map of a region, wherein the magnetic-field map comprises a plurality of map points that correspond to locations in the region and are associated with magnetic-field values corresponding to the locations in the region;
• means for accessing a trajectory, wherein the trajectory comprises a plurality of trajectory points that correspond to a path and are associated with magnetic-field values measured along the path;
• means for comparing the magnetic-field values associated with the trajectory points with the magnetic-field values associated with the map points;
• means for identifying, based on the comparison, one or more of the trajectory points that approximately magnetically coincide with one or more of the map points;
• means for adjusting, based on the identification, one or more of the trajectory points to be approximately colocated with one or more of the map points;
• and
• means for incorporating the trajectory points and the magnetic-field values associated with them as adjusted into the magnetic-field map.