Magnetic tracking calibration via distortion correction for electromagnetic fields using inside-out tracking
Inventors
Schneider, Mark Robert • Duling, Alec • Karyattuparambil Rajagopalan, Syamprasad
Assignees
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Publication Number
US-12207888-B2
Publication Date
2025-01-28
Expiration Date
Abstract
A magnetic tracking device is configured to track an object in an environment by receiving a measurement of the non-magnetic signal and a corresponding measurement of the magnetic signal for a location of the magnetic tracking device in the environment. The magnetic tracking device estimates, based on the measurement of the non-magnetic signal, a non-magnetic pose of the magnetic tracking device in the environment for the location. The device estimates, based on the measurement of the magnetic signal, a magnetic pose of the magnetic tracking device in the environment for the location. The device determines a difference between the magnetic pose estimate and the non-magnetic pose estimate for the location. The device determines a magnetic distortion correction value for the location based on the difference. The magnetic tracking device generates a distortion correction model including the distortion value and outputs a representation of the distortion correction model.
Core Innovation
A magnetic tracking system determines an object pose in an environment by combining magnetic tracking with a non-magnetic sensing path and generating a location-dependent distortion correction model. The system includes a scaffold and a magnetic tracking device that measures a non-magnetic signal generated using a set of optical markers that are reconfigurable for placement at different locations within the environment. The magnetic tracking device further measures a magnetic signal, and the non-magnetic signal detector comprises a camera coupled to the magnetic signal detector.
A computing device receives a set of measurements of the non-magnetic signal and a corresponding measurement of the magnetic signal by moving the magnetic tracking device to different locations. From the non-magnetic measurements, the computing device estimates a non-magnetic pose of the magnetic tracking device at each location, and from the magnetic measurements it estimates a magnetic pose at the corresponding locations. The computing device determines a difference between the magnetic pose estimate and the non-magnetic pose estimate for each location, determines a magnetic distortion correction value for each location, and generates a distortion correction model that includes the magnetic distortion correction value for each location.
The computing device refines the distortion correction model by rearranging one or more sources of the non-magnetic signal in the environment, receiving an updated measurement of the non-magnetic signal based on the rearranged one or more sources, and updating the distortion correction model using the updated measurement. The system outputs a representation of the distortion correction model. The approach is described as an inside-out magnetic tracking calibration concept in which magnetic signal measurements are corrected using a model derived from differences between magnetic pose estimates and non-magnetic pose estimates at known locations.
Claims Coverage
The document provides one independent claim that sets the overall system architecture and calibration workflow to generate a distortion correction model from differences between magnetic pose and non-magnetic pose at multiple locations. The dependent claims refine optical marker sensing details, non-magnetic signal types, transmitter assembly subcomponents, tracked medical device targets, and a planar-surface-based measurement workflow.
Magnetic tracking system with reconfigurable optical-marker non-magnetic sensing
A magnetic tracking system for determining an object pose, comprising a scaffold; a magnetic tracking device with a non-magnetic signal detector configured to measure a non-magnetic signal generated using a set of optical markers that are reconfigurable for placement at different locations; and a magnetic signal detector coupled to the non-magnetic signal detector. The non-magnetic signal detector comprises a camera, and the camera and the magnetic signal detector are movable to different portions of the scaffold to capture images of the optical markers at different locations placed at known relative distances based on a position of the scaffold.
Location-based distortion correction model from magnetic and non-magnetic pose differences
A computing device receives measurements of the non-magnetic signal and corresponding measurements of the magnetic signal at multiple different locations, estimates a non-magnetic pose based on the non-magnetic signal and a magnetic pose based on the magnetic signal, determines a difference between the pose estimates at each location, determines a magnetic distortion correction value for each location based on the difference, and generates a distortion correction model including the correction value for each location.
Refinement of distortion correction model using rearrangement of non-magnetic sources
The computing device refines the distortion correction model by rearranging one or more sources of the non-magnetic signal in the environment, receiving an updated measurement of the non-magnetic signal based on the rearranged sources, updating the distortion correction model using the updated measurement, and outputting a representation of the distortion correction model.
Overall, the independent claim covers a magnetic tracking system that uses movable camera-based optical-marker sensing to obtain non-magnetic pose at multiple scaffold-linked locations, compares it to magnetic pose estimates to compute per-location magnetic distortion correction values, and generates and outputs a distortion correction model that is further refined by rearranging sources used to generate the non-magnetic signal.
Stated Advantages
Generates and outputs a distortion correction model based on magnetic pose and non-magnetic pose differences at different locations.
Refines the distortion correction model by rearranging one or more sources of the non-magnetic signal and updating using updated non-magnetic measurements.
Documented Applications
Tracking a medical device, where the tracked object is one of a catheter, an endoscope, or a surgical instrument.
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