Methods for locating and tracking a tool axis

Patent metadata

Field	Value
Publication number	US-10792109-B2
Application number	US-201615548138-A
Country	US
Kind code	B2
Filing date	Mar 7, 2016
Priority date	Mar 5, 2015
Publication date	Oct 6, 2020
Grant date	Oct 6, 2020

Abstract

A calibration device is provided having a body with an exterior surface configured for placement about a tool such that the body rotates about a tool axis. One or more fiducial marker is positioned on the exterior surface and in communication with a tracking system. A fixed fiducial marker array is provided that is also in communication with the tracking system. A calibration tool defines the tool axis relative to the fiducial marker array. A surgical system is also provided with a tracking module that calculates a center point of the rotation or a normal vector to the circular path to define a tool axis orientation. A method of using the surgical system and defining a tool axis relative to a fiducial marker array is provided. A system for defining a robot link orientation or tracking a tool a medical procedure and a fiducial marker array are provided.

First claim

The invention claimed is:

1. A calibration device comprising:
a body with an exterior surface, said body comprising two or more attachment points or clips joined with a rigid member, where said body is configured for placement on a tool having a tool axis such that said body can rotate about the tool axis;
one or two fiducial markers positioned on said rigid member affixed to the exterior surface of said body, where said one or two fiducial markers are tracked by a tracking system; and
wherein rotation of said calibration device allows for a determination of said tool axis.

2. The calibration device of claim 1 wherein said one or two fiducial markers are offset axially along a longitudinal axis of said body.

3. A calibration device comprising:
a body that is a hollow cylindrical sleeve with an exterior surface, said body configured for placement on a tool having a tool axis such that said body can rotate about the tool axis;
at least one fiducial marker affixed to the exterior surface of said body of said calibration device, where said at least one fiducial marker is tracked with a tracking system;
wherein rotation of said calibration device allows for a determination of said tool axis.

4. The calibration device of claim 3 wherein said at least one fiducial marker is positioned at a known distance from a first end of said hollow cylindrical sleeve.

5. The calibration device of claim 3 wherein said hollow cylindrical sleeve further comprises a first end with an abutment surface, and where a position of at least one fiducial marker of said at least one fiducial marker is a known distance from said abutment surface.

6. A surgical system comprising:
a tool having a tool axis;
a tracking system;
a fiducial marker array fixed to said tool and tracked by said tracking system;
a calibration device comprising a body with at least one fiducial marker positioned on said body, where said body is configured for placement on said tool such that said body can rotate about the tool axis; and
wherein in response to the rotation of said body one or more circular paths are generated by said at least one fiducial marker that are tracked by said tracking system, and said tracking system calculates at least one of a center point of the rotation or a normal vector to the circular path to define a tool axis orientation relative to said fiducial marker array fixed to said tool and to said tracking system.

7. The surgical system of claim 6 wherein said calibration device is a hollow cylindrical sleeve with two or more fiducial markers offset axially along a longitudinal axis of said hollow cylindrical sleeve.

8. A method for defining a position of a tool center point at a working end of a tool with respect to said fiducial marker array comprising:
providing the surgical system of claim 6 where the tracking system is used in the determination of:
a) an intersection of the normal vector of the one or more circular paths traced by said at least one fiducial marker at the center point of the rotation, and
b) a plane defined by an abutment surface on said calibration device that is a known distance from the fiducial marker.

9. A method for determining the tool axis orientation comprising:
providing the surgical system of claim 6 wherein said tracking system calculates at least one of:
a) the average of the normal vectors to the circular paths traced by two or more rotated fiducial markers,
b) the average of the normal vectors between the center points of the circular paths traced by the two or more rotated fiducial markers, or
c) the average of a and b.

10. A method for defining a tool axis relative to a fiducial marker array comprising:
fixing said fiducial marker array to a tool;
attaching a calibration device with at least one fiducial marker on the tool;
rotating said calibration device about the tools axis;
tracking the rotation of said at least one fiducial marker with a tracking system; and
calculating a normal vector and a center point from one or more circular paths traced by the fiducial marker rotation to define the tool axis orientation relative to the fiducial marker array.

11. The method of claim 10 further comprising:
collecting a set of points on a tool tip surface of said tool with a digitizer;
best-fitting a plane to the collected set of points with a processor; and
defining the position of a tool center point at said tool tip surface relative to the fiducial marker array from the intersection of the normal vector at the center point of rotation and the best-fit plane.

12. The method of claim 10 further comprising:
actuating a robot with said calibration device to a previously calibrated tool axis at a given robot position and orientation (pose);
rotating said calibration device about the tool axis;
recording the position of the fiducial marker during rotation with the tracking module;
fitting a circular model to the recorded positions with a processor;
calculating at least one of the circles diameter, center, or normal vector; and
comparing at least one of the circles diameter, center, or normal vector with the values stored from the previously calibrated tool axis to determine the robot calibration validity.

13. The method of claim 10 wherein one end of said calibration device further comprises a sleeve with an abutment surface whereby the fiducial marker on said sleeve is at a known distance from the abutment surface.

14. The method of claim 13 further comprising:
calculating the position of a tool center point at the working end of the tool based on the intersection of the calculated normal vector to the circular paths traced by the fiducial marker at the center point of rotation and a plane defined at the abutment surface.

15. A system for tracking a tool to aid in a medical procedure comprising:
a tool;
a tracking system;
a rotating body coincident about an axis of said tool, said rotating body comprising at least one fiducial marker such that said tracking system records a position of the at least one fiducial marker as the at least one fiducial marker rotates about the tool axis; and
a processor configured for calculating at least one of a vector normal to a fitted circle or a center point of the fitted circle.

16. The system of claim 15 wherein said processor is also programmed to fit a circle to the recorded positions of the fiducial marker.

17. The system of claim 15 wherein the tracking system records the position of the at least one fiducial marker during rotation and said processor is configured for fitting a circular model to the recorded positions and calculating at least one of a circle center or vector normal to the circle to define at least one of a distal link position or distal link orientation.

Assignees

• Think Surgical Inc

Inventors

• Bonny Daniel Patrick
• Zuhars Joel
• Netravali Nathan A

Classifications

• A61B2017/00725

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• A61B90/39

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• A61B2090/3983

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• A61B2034/2055

  Optical tracking systems · CPC title

• A61B34/20 Primary

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