Planning a tool path for an end-effector using an environmental map

Abstract

A system and method are provided for planning a tool path for an end-effector of a surgical robot from a first position to a second position using an environmental map. The end-effector may safely and efficiently follow the tool path to re-position the end-effector back to a cutting position following the displacement of the end-effector from the cutting position. Additionally, the environmental map is used to update a virtual representation of a bone to provide a user with visual feedback as to the progression of the end-effector tool as the tool removes material from the bone during a surgical procedure.

1 . A method for planning a tool path for an end-effector attached to a surgical robot comprising:
 providing motion planner software on a computer having a processor and an environmental map with physical areas designated in the environmental map as free space or invalid space, wherein the free space is a volume based on removed material and the invalid space is intact material; and   planning the tool path for the end-effector from a first position to a second position, with the motion planner software, using the environmental map.   
     
     
         2 . The method of  claim 1  wherein the material is a workpiece or a bone. 
     
     
         3 . The method of  claim 1  further comprising generating the environmental map by labelling the free space and the invalid space relative to the end-effector. 
     
     
         4 . The method of  claim 3  further comprising labelling of the removed material as free space only when the end-effector is in an ‘on’ operating state. 
     
     
         5 . The method of  claim 3  further comprising the labelling of the removed material as free space in only when the end-effector crosses a boundary in a direction towards the workpiece or the bone. 
     
     
         6 . The method of  claim 3  further comprising defining a boundary in the environmental map based a plane non-parallel to a longitudinal axis of the workpiece or the bone. 
     
     
         7 . The method of  claim 6  wherein the free space is labelled starting at the boundary and away from the workpiece or the bone and the invalid space is labelled starting at the boundary and towards the orthopedic workpiece or the bone. 
     
     
         8 . The method of  claim 1  wherein the environmental map is defined with reference to a robotic coordinate system or a tracking system coordinate system. 
     
     
         9 . The method of  claim 1  further comprising registering a bone relative to the surgical robot. 
     
     
         10 . The method of  claim 1  wherein the first position is a displaced position of the end-effector from a previous tool path and the second position resides along the previous tool path. 
     
     
         11 . The method of  claim 1  wherein the tool path is limited to the free space. 
     
     
         12 . The method of  claim 1  wherein the tool path is planned by minimizing a path length from the first position to the second position in the free space. 
     
     
         13 . The method of  claim 11  wherein the tool path is planned by avoiding obstacles utilizing the invalid space. 
     
     
         14 . The method of  claim 11  wherein the minimizing of the path length is accomplished with an algorithm including at least one of: optimization algorithms, probability roadmaps (PRM), rapidly-exploring random trees (RRT), or potential field methods. 
     
     
         15 . The method of  claim 1  further comprising identifying one or more checkpoints between the first position and the second position wherein the planning of the tool path from the first position to, or near, the second position utilizes the one or more of the checkpoints. 
     
     
         16 . The method of  claim 14  further comprising determining which of the one or more checkpoints is in closest proximity to the second position and planning the tool path based on one or more of said checkpoints. 
     
     
         17 . The method of  claim 1  further comprising removing the material with the end-effector. 
     
     
         18 . A surgical system comprising:
 a surgical robot with an end effector; and   a computer comprising a processor and motion planner software to plan the tool path of  claim 1 .   
     
     
         19 . The system of  claim 17  further comprising an environmental map generator software for generating an environmental map. 
     
     
         20 . The system of claim of  claim 18  further comprising at least one of a mechanical digitizer or a non-mechanical tracking system.