Robotic systems and methods for tool path generation and control based on bone density

1. A surgical robotic system comprising:

a manipulator including a plurality of links and joints;

a tool coupled to the manipulator and the tool being configured to remove material from a workpiece; and

one or more controllers coupled to the manipulator, the one or more controllers being configured to:

generate a first tool path to remove a first portion of material from the workpiece;

control the manipulator to position the tool for movement along the first tool path to remove the first portion of material from the workpiece;

sense interaction between the tool and the workpiece during movement of the tool along the first tool path to determine a density of the workpiece;

generate a second tool path to remove a second portion of material from the workpiece, wherein generation of the second tool path is based, at least in part, on the sensed interaction between the tool and the workpiece during movement of the tool along the first tool path; and

control the manipulator to position the tool for movement along the second tool path to remove the second portion of material from the workpiece and to account for the density of the workpiece by being configured to control one or both of: a feed rate of the tool and a cutting speed of the tool.

2. The surgical robotic system of claim 1 , wherein the one or more controllers are configured to:

generate the first tool path to remove the first portion of material from the workpiece at a first level; and

generate the second tool path to remove the second portion of material from the workpiece at a second level that is different from the first level.

3. The surgical robotic system of claim 2 , wherein:

the first level is at a first cutting depth and the second level is at a second cutting depth that is greater than the first cutting depth; and/or

the second level is below the first level.

4. The surgical robotic system of claim 1 , wherein:

the manipulator comprises a force/torque sensor to detect forces/torques experienced by the tool; and

the one or more controllers further sense interaction between the tool and the workpiece by being configured to determine forces/torques experienced by the tool encountering the workpiece during movement along the first tool path.

5. The surgical robotic system of claim 1 , wherein the one or more controllers are configured to generate the first tool path based on one or more density values of the workpiece.

6. The surgical robotic system of claim 5 , wherein the one or more density values comprise a density distribution of the workpiece determined from a three-dimensional representation of the workpiece, and wherein the one or more controllers are configured to:

evaluate the density distribution of the workpiece to identify a first density classification for the first portion of material of the workpiece; and

generate the first tool path based on the identified first density classification.

7. The surgical robotic system of claim 6 , wherein the one or more controllers are configured to:

evaluate the density distribution of the workpiece to identify a second density classification for the second portion of material of the workpiece; and

generate the second tool path based, at least in part, on the identified second density classification.

8. The surgical robotic system of claim 1 , wherein the one or more controllers are configured to control the manipulator in a manual mode of operation to assist a user with movement of the tool along the first tool path and to assist the user with movement of the tool along the second tool path.

9. The surgical robotic system of claim 1 , further comprising a navigation system including a localizer configured to track the tool and the workpiece and wherein the navigation system is configured to track a state of the tool relative to the workpiece as the tool moves relative to the workpiece.

10. The surgical robotic system of claim 1 , wherein the tool is further defined as a saw blade.

11. The surgical robotic system of claim 1 , wherein the workpiece is a femur and the first portion of material of the femur and the second portion of material of the femur are removed to receive a total knee implant.

12. A method of operating a surgical robotic system, the surgical robotic system comprising a manipulator including a plurality of links and joints and a tool coupled to the manipulator, the tool being configured to remove material from a workpiece, and one or more controllers coupled to the manipulator, the method comprising:

generating, with the one or more controllers, a first tool path to remove a first portion of material from the workpiece;

controlling, with the one or more controllers, the manipulator to position the tool for movement along the first tool path for removing the first portion of material from the workpiece;

during movement of the tool along the first tool path, sensing, with the one or more controllers, interaction between the tool and the workpiece for determining a density of the workpiece;

generating, with the one or more controllers, a second tool path to remove a second portion of material from the workpiece, wherein generating the second tool path is based, at least in part, on the sensed interaction between the tool and the workpiece during movement of the tool along the first tool path; and

controlling, with the one or more controllers, the manipulator to position the tool for movement along the second tool path for removing the second portion of material from the workpiece and to account for the density of the workpiece by controlling one or both of: a feed rate of the tool and a cutting speed of the tool.

13. The method of claim 12 , comprising:

generating, with the one or more controllers, the first tool path to remove the first portion of material from the workpiece at a first level; and

generating, with the one or more controllers, the second tool path to remove the second portion of material from the workpiece at a second level that is different from the first level.

14. The method of claim 13 , comprising the one or more controllers generating the first tool path and the second tool path such that:

the first level is at a first cutting depth and the second level is at a second cutting depth that is greater than the first cutting depth; and/or

the second level is below the first level.

15. The method of claim 12 , wherein the manipulator comprises a force/torque sensor to detect forces/torques experienced by the tool, wherein sensing interaction further comprises the one or more controllers determining forces/torques experienced by the tool encountering the workpiece during movement along the first tool path.

16. The method of claim 12 , comprising:

obtaining, with the one or more controllers, a density distribution of the workpiece determined from a three-dimensional representation of the workpiece;

evaluating, with the one or more controllers, the density distribution of the workpiece to identify a first density classification for the first portion of material of the workpiece;

evaluating, with the one or more controllers, the density distribution of the workpiece to identify a second density classification for the second portion of material of the workpiece;

generating, with the one or more controllers, the first tool path based on the identified first density classification; and

generating, with the one or more controllers, the second tool path based, at least in part, on the identified second density classification.