Robotic Systems And Methods For Controlling A Tool Removing Material From A Workpiece

Patent metadata

Field	Value
Publication number	US-2019021802-A1
Application number	US-201816139985-A
Country	US
Kind code	A1
Filing date	Sep 24, 2018
Priority date	Jul 1, 2015
Publication date	Jan 24, 2019
Grant date	—

Abstract

A method of operating a robotic system to efficiently remove material from a workpiece based on a density distribution of the material of the workpiece. The density distribution of the material of the workpiece is determined from a three-dimensional representation and evaluated by classifying the plurality of points or voxels into a first density classification and a second density classification. A navigation computer generates a first tool path and a second tool path for the tool based on the evaluated density distribution. The first tool path is associated with the first density classification, and the second tool path is associated with the second density classification. The position of the tool relative to the workpiece is tracked with a navigation computer and controlled with a manipulator controller based on the generated tool path to remove material along the first tool path, and remove material along the second tool path.

First claim

What is claimed is:

1 . A method of operating a robotic system including a manipulator, a tool coupled to the manipulator to remove material from a workpiece, a manipulator controller coupled to the manipulator, and a navigation computer, said method comprising:
determining a density distribution of material of the workpiece from a three-dimensional representation of the workpiece comprising a plurality of points or voxels; evaluating the density distribution by classifying the plurality of points or voxels into a first density classification and a second density classification different than the first density classification; generating with the navigation computer a first tool path for the tool based on the evaluated density distribution of the workpiece and associated with the first density classification, and a second tool path for the tool based on the evaluated density distribution and associated with the second density classification; tracking with the navigation computer a position of the tool relative to the workpiece as the tool moves relative to the workpiece; and controlling with the manipulator controller the position of the tool relative to the workpiece based on the generated tool path to remove at least a portion of the material along the first tool path, and remove at least a portion of the material along the second tool path.

2 . The method of claim 1 , wherein the step of evaluating the density distribution further comprises classifying the plurality of points or voxels into the first and second density classifications relative to a predetermined density threshold.

3 . The method of claim 2 , wherein the points or voxels classified into first density classification are above the predetermined density threshold, and the points or voxels classified into the second density classification are below the predetermined density threshold.

4 . The method of claim 1 , further comprising assigning a density coefficient to each of the plurality of points or voxels in the three-dimensional model based on measurements taken of the workpiece.

5 . The method of claim 4 , wherein the step of evaluating the density distribution further comprises comparing the assigned density coefficients for each of the plurality of points or voxels to a predetermined density threshold.

6 . The method of claim 4 , further comprising averaging assigned density coefficients from adjacent points or voxels to determine a common density coefficient for a cluster of the points or voxels.

7 . The method of claim 4 , wherein the assigned density coefficients are between zero and one.

8 . The method of claim 1 , further comprising one of controlling the position of the tool to remove the material along the first tool path prior to removing the material along the second tool path, and controlling the position of the tool to remove the material along the second tool path prior to removing the material along the first tool path.

9 . The method of claim 1 , wherein the first and second tool paths include a cutting depth, said method further comprising altering the cutting depth of the first and second tool paths based on the first and second density classifications to remove at least a portion of the material along the first tool path at a first cutting depth, and remove at least a portion of the material of the second tool path at a second cutting depth being different than the first cutting depth.

10 . The method of claim 9 , wherein the first density classification is representative of denser material relative to less dense material represented by the second density classification, and wherein the first cutting depth is shallower than the second cutting depth.

11 . The method of claim 10 , wherein the denser material is cortical bone, and the less dense material is cancellous bone.

12 . The method of claim 1 , wherein the first and second tool paths include a plurality of contiguous tool path segments, wherein said method further comprises generating the first and second tool paths along each of the tool path segments based on the evaluated density distribution for the respective tool path segments.

13 . The method of claim 12 , wherein the step of generating the first and second tool paths for each of the tool segments is performed as the tool moves relative to the workpiece.

14 . The method of claim 12 , wherein the tool path segments are vector or curves that extends between the plurality of points or voxels.

15 . The method of claim 1 , wherein the first and second tool paths have a plurality of levels, wherein the step of controlling the position of the tool relative to the workpiece is performed iteratively for each of the plurality of levels.

16 . The method of claim 1 , wherein the first and second tool paths have a first level above a second level, wherein said method further comprises controlling with the manipulator controller the position of the tool to remove at least a portion of the material from the first level at a first cutting depth based on the determined density distribution, and remove at least a portion of the material from the first level at a second cutting depth different than the first cutting depth and based on the determined density distribution.

17 . The method of claim 16 , further comprising, after the material from the first level is removed, controlling with the manipulator controller the position of the tool relative to the workpiece to remove at least a portion of the material from the second level.

18 . The method of claim 1 , wherein the first density classification is representative of denser material relative to less dense material represented by the second density classification, and wherein the denser material is located within two noncontiguous regions separated by a region of the less dense material, wherein said method further comprises controlling the position of the tool to remove a first of the two noncontiguous regions of the denser material and the region of the less dense material prior to removing a second of the two noncontiguous regions of the denser material.

19 . The method of claim 19 , where the two noncontiguous regions of the denser material are of different volumes, wherein said method further comprises controlling the position of the tool to remove the larger volume of the two noncontiguous regions of the denser material prior to removing the smaller volume of the two noncontiguous regions of the denser material.

20 . The method of claim 1 , further comprising assigning or adjusting a feed rate of the tool preoperatively or intraoperatively.

Assignees

• Mako Surgical Corp

Inventors

• Moctezuma De La Barrera José Luis
• Bowling David Gene
• Malackowski Donald W
• Roessler Patrick
• Beer Joel N

Classifications

• A61B34/10

  Computer-aided planning, simulation or modelling of surgical operations · CPC title

• A61B2034/105

  Modelling of the patient, e.g. for ligaments or bones · CPC title

• A61B2034/2055

  Optical tracking systems · CPC title

• B25J9/1664

  characterised by motion, path, trajectory planning · CPC title

• B25J9/1671

  characterised by simulation, either to verify existing program or to create and verify new program, CAD/CAM oriented, graphic oriented programming systems · CPC title