Robotic systems and methods for controlling a tool removing material from a workpiece

Patent metadata

Field	Value
Publication number	US-11291511-B2
Application number	US-201816139985-A
Country	US
Kind code	B2
Filing date	Sep 24, 2018
Priority date	Jul 1, 2015
Publication date	Apr 5, 2022
Grant date	Apr 5, 2022

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, wherein the workpiece includes a density distribution of material determined from a three-dimensional representation of the workpiece that includes a plurality of points or voxels, said method comprising:
evaluating with the navigation computer 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;
thereafter, with the navigation computer:
identifying a first portion of the material derived from the first density classification;
generating a first tool path for the tool for a first level of the material, the first tool path having a configuration enabling the tool to remove the first portion of the material;
identifying a second portion of the material derived from the second density classification; and
generating a second tool path for the tool for a second level of the material below the first level of the material, the second tool path having a configuration enabling the tool to remove the second portion of the material;

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 to remove at least a portion of the material along the first tool path; and
thereafter, controlling with the manipulator controller the position of the tool relative to the workpiece to 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, 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.

3. 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; and
comparing the assigned density coefficients for each of the plurality of points or voxels to a predetermined density threshold.

4. The method of claim 3 , 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.

5. The method of claim 1 , wherein the first tool path includes a plurality of contiguous tool path segments, wherein said method further comprises altering the first tool path between the tool path segments based on the evaluated density distribution for the respective tool path segments.

6. The method of claim 5 , further comprising generating the first tool path for each of the tool path segments as the tool moves relative to the workpiece.

7. The method of claim 5 , wherein the tool path segments are vector or curves that extends between the plurality of points or voxels.

8. The method of claim 1 , wherein the first density classification is indicative of denser material relative to the second density classification being indicative of less dense material, 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; and
thereafter, controlling the position of the tool to remove a second of the two noncontiguous regions of the denser material.

9. The method of claim 8 , 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 a larger volume of the two noncontiguous regions of the denser material; and
thereafter, removing a smaller volume of the two noncontiguous regions of the denser material.

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

11. The method of claim 1 , wherein the step of generating with the navigation computer the second tool path is performed after the material is removed along the first tool path.

12. The method of claim 1 , wherein the first level and the second level have a depth equal to a diameter of the tool.

13. The method of claim 1 , further comprising:
controlling with the manipulator controller the position of the tool relative to the workpiece to remove the material along the first tool path at a first cutting depth; and
controlling with the manipulator controller the position of the tool relative to the workpiece to remove the material along the second tool path at a second cutting depth greater than the first cutting depth based on the second density classification being indicative that the second portion of the material is less dense than the first portion of the material of the first density classification.

14. A robotic system for removing material from a workpiece having a density distribution of material determined from a three-dimensional representation of the workpiece that includes a plurality of points or voxels, the robotic system comprising:
a manipulator;
a tool coupled to the manipulator to remove the material from the workpiece;
a manipulator controller coupled to the manipulator and configured to control a position of the tool relative to the workpiece; and
a navigation computer in communication with the manipulator controller and configured to track a position of the tool relative to the workpiece,
wherein the navigation computer is configured to:
evaluate 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;
thereafter, generate a first tool path for the tool for a first level of the material based on the evaluated density distribution of the workpiece and associated with the first density classification; and
thereafter, generate a second tool path for the tool for a second level of the material below the first level of the material, the second tool path based on the evaluated density distribution and associated with the second density classification,

wherein the manipulator controller is configured to:
control the position of the tool relative to the workpiece to remove at least a portion of the material along the first tool path; and
thereafter, control the position of the tool relative to the workpiece to remove at least a portion of the material along the second tool path.

15. The robotic system of claim 14 , wherein the manipulator controller is further configured to control the position of the tool to remove the material along the first tool path prior to removing the material along the second tool path.

16. The robotic system of claim 14 , wherein the first tool path includes a plurality of contiguous tool path segments, wherein the navigation computer is further configured to alter the first tool path between the tool path segments based on the evaluated

Assignees

• Mako Surgical Corp

Inventors

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

Classifications

• B25J9/1664

  characterised by motion, path, trajectory planning · CPC title

• A61B2090/3945

  Active visible markers, e.g. light emitting diodes · CPC title

• G05B2219/45168

  Bone prosthesis · CPC title

• A61B34/10

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

• B25J11/0055

  Cutting · CPC title