Method and system for steerable medical device path definition and following during insertion and retraction

Abstract

Waypoints for a steerable medical device are stored as the steerable medical device is moved within a patient. The stored waypoints are an ordered sequence of locations. The ordered sequence of locations defines a safe path within the patient for moving an articulatable portion of the steerable medical device. The articulatable portion of the steerable medical device is constrained to follow the safe path as the articulatable portion moves within the patient. For example, the articulatable portion of the steerable medical device is constrained to remain within a boundary region enclosing the safe path as the articulatable portion of the steerable medical device follows the safe path.

We claim: 
     
         1 . A method comprising:
 storing, by a controller, waypoints of a tip of a steerable medical device as the steerable medical device is moved towards a desired location in a patient, the steerable medical device including an articulatable segment, the articulatable segment including a plurality of links with each link in the plurality of links being coupled to another link in the plurality of links by a joint;   defining, by the controller as the steerable medical device is moved towards the desired location, a boundary region, the boundary region being a three-dimensional volume enclosing locations of the stored waypoints, the controller using the stored waypoints in the defining the boundary region; and   moving, by the controller as the steerable medical device is moved towards the desired location, the articulatable segment along a path determined using the stored waypoints while constraining the articulatable segment to remain within the boundary region while one or more of the plurality of links deviate from the path as the articulatable segment is moved.   
     
     
         2 . The method of  claim 1 , wherein the boundary region comprises a tube having a cross-section. 
     
     
         3 . The method of  claim 2 , wherein the cross-section comprises one of a circular cross-section, an oblate cross-section, and a rectangular cross-section. 
     
     
         4 . The method of  claim 1 , wherein the articulatable segment is included in a plurality of segments of the steerable medical device. 
     
     
         5 . The method of  claim 4 , wherein the constraining the articulatable segment to remain within the boundary region further comprises:
 generating position and orientation data for each of the plurality of segments using stored waypoints and a kinematic model of the plurality of segments of the steerable medical device.   
     
     
         6 . The method of  claim 5  wherein the generating position and orientation data for each of the plurality of segments further comprises:
 minimizing a cost function to generate the position and orientation data for each of the plurality of segments. 
 
     
     
         7 . The method of  claim 6  wherein the minimizing a cost function further comprises:
 minimizing a sum of absolute values of relative joint angles, with an additional constraint that link positions not deviate by more than a distance Δ at each of the waypoints. 
 
     
     
         8 . The method of  claim 1 , wherein the constraining the articulatable segment to remain within the boundary region further comprises:
 retrieving, by the controller, the stored waypoints; and   generating, by the controller using the waypoints, a configuration of the articulatable segment.   
     
     
         9 . The method of  claim 8 , wherein the constraining the articulatable segment to remain within the boundary region further comprises:
 sending, to a medical device controller coupled to the steerable medical device, at least one command, based on the configuration to constrain the articulatable segment.