# US 12,178,540 B2 · Systems and methods for controlling movement of a surgical tool along a predefined path class

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- Number: US 12,178,540 B2
- Document ID: US12178540B2
- Status: Granted
- Kind: B2
- Application number: 18/093,384
- Filed: 2023-01-05
- Published: 2023-05-11
- Granted: 2024-12-31
- Earliest claimed: 2019-03-08
- Assignees: MAKO Surgical Corp.
- Applicants: MAKO Surgical Corp.
- Inventors: Helmut Rohs; Michael Dale Dozeman; Bharat Arora; Michael Ferko; Patrick Roessler; Richard Thomas DeLuca; David Gene Bowling
- Web page: https://patentgrep.com/patent/US12178540B2

## CPC

- A61B 34/70: {Manipulators specially adapted for use in surgery}
- A61B 34/76: {Manipulators having means for providing feel, e.g. force or tactile feedback}
- A61B 34/10: Computer-aided planning, simulation or modelling of surgical operations
- A61B 34/20: Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
- A61B 34/30: Surgical robots
- A61B 34/37: Leader-follower robots (A61B34/35 takes precedence)
- A61B 34/74: {Manipulators with manual electric input means}
- A61B 90/06: {Measuring instruments not otherwise provided for}
- A61B 2034/104: {Modelling the effect of the tool, e.g. the effect of an implanted prosthesis or for predicting the effect of ablation or burring}
- A61B 2034/107: {Visualisation of planned trajectories or target regions}
- A61B 2034/108: {Computer aided selection or customisation of medical implants or cutting guides}
- A61B 2034/2046: {Tracking techniques}
- A61B 2034/2055: {Optical tracking systems}
- A61B 2034/2059: {Mechanical position encoders}
- A61B 2034/2068: {using pointers, e.g. pointers having reference marks for determining coordinates of body points}
- A61B 2090/064: {for measuring force, pressure or mechanical tension}
- A61B 2090/066: {for measuring torque}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

Robotic surgical systems and methods for controlling movement of a tool relative to a tool path. An input is received from a force/torque sensor in response to user forces/torques manually applied to the tool by a user. A component of force is calculated tangential to the path based on the input. An effective feed rate is calculated to advance the tool along the path based on the tangential component. Virtual constraints are defined on movement of the tool along the path with respect to three degrees of freedom and based on the effective feed rate to promote movement of the tool along the path. Dynamics of the tool are virtually simulated based on the virtual constraints and the input from the force/torque sensor. The manipulator is commanded to advance the tool along the path based on the virtual simulation.

## Claims

### Claim 1

A robotic surgical system comprising:
a surgical tool;
a manipulator configured to support the surgical tool, the manipulator comprising a plurality of links;
a force/torque sensor to measure forces and torques applied to the surgical tool; and
a control system configured to:
obtain a tool path for the surgical tool, wherein the tool path is three-dimensional and pre-defined;
receive an input from the force/torque sensor in response to user forces and torques manually applied to the surgical tool by a user;
calculate, based on the input from the force/torque sensor, a tangential component of force that is tangential to the tool path;
calculate an effective feed rate for advancing the surgical tool along the tool path based on the calculated tangential force component and by excluding normal components of force that are normal to the tool path;
define virtual constraints on movement of the surgical tool along the tool path with respect to three degrees of freedom and based on the effective feed rate to promote movement of the surgical tool along the tool path;
simulate dynamics of the surgical tool in a virtual simulation based on the input from the force/torque sensor; and
command the manipulator to advance the surgical tool along the tool path based on the virtual simulation.

### Claim 2 (depends on 1)

The robotic surgical system of claim 1 wherein the control system is further configured to simulate dynamics of the surgical tool by representing the surgical tool as a virtual rigid body having a virtual mass and by applying a constraint force to the virtual mass in the virtual simulation to yield a commanded pose, wherein the constraint force is based on the virtual constraints.

### Claim 3 (depends on 2)

The robotic surgical system of claim 2, wherein the control system is configured to determine a target pose on the tool path based on the effective feed rate.

### Claim 4 (depends on 3)

The robotic surgical system of claim 3, wherein the control system is configured to define the virtual constraints with respect to the three degrees of freedom on a distance between the commanded pose and the target pose.

### Claim 5 (depends on 1)

The robotic surgical system of claim 1, wherein the control system is configured to:
define one or more additional constraints associated with constraining an orientation of the surgical tool;
simulate dynamics of the surgical tool in the virtual simulation based on the virtual constraints, the one or more additional constraints, and the input from the force/torque sensor; and
command the manipulator to advance the surgical tool along the tool path based on the virtual simulation.

### Claim 6 (depends on 1)

The robotic surgical system of claim 1, wherein:
the manipulator is operable in a guided-manual mode and a semi-autonomous mode and wherein the control system is further configured to utilize the effective feed rate and define the virtual constraints in the guided-manual mode; and
in response to transitioning to the semi-autonomous mode from the guided-manual mode, the control system is configured to calculate a transition path from a current position of a tool center point of the surgical tool to a last known point of the surgical tool on the tool path before transitioning from the semi-autonomous mode.

### Claim 7 (depends on 1)

The robotic surgical system of claim 1, wherein the control system is configured to:
obtain a virtual boundary for the surgical tool with the virtual boundary being a three-dimensional tube defining the tool path; and
define the virtual constraints on movement of the surgical tool inside the three-dimensional tube and along the tool path, the virtual constraints being defined to constrain movement of the surgical tool to be along the tool path.

### Claim 8 (depends on 1)

The robotic surgical system of claim 1, wherein the virtual constraints are defined as velocity constraints, wherein each of the velocity constraints comprises stiffness and damping parameters and one or more force limits and one or more activation limits.

### Claim 9 (depends on 1)

The robotic surgical system of claim 1, wherein the control system is configured to determine a direction of movement to move the surgical tool along the tool path based on the calculated tangential force component.

### Claim 10 (depends on 1)

The robotic surgical system of claim 1, wherein the control system is configured to:
define an end constraint with respect to one degree of freedom tangential to the tool path to constrain the surgical tool to remain on the tool path by constraining movement beyond an end of the tool path.

### Claim 11

A method for operating a robotic surgical system, the robotic surgical system comprising a surgical tool, a manipulator configured to support the surgical tool, and a force/torque sensor to measure forces and torques applied to the surgical tool, the method comprising the steps of:
obtaining a tool path for the surgical tool, wherein the tool path is three-dimensional and pre-defined;
receiving input from the force/torque sensor in response to user forces and torques manually applied to the surgical tool by a user;
calculating a tangential component of force that is tangential to the tool path based on the input from the force/torque sensor;
calculating an effective feed rate to advance the surgical tool along the tool path based on the calculated tangential component and by excluding normal components of force that are normal to the tool path;
defining virtual constraints on movement of the surgical tool along the tool path with respect to three degrees of freedom and based on the effective feed rate to promote movement of the surgical tool along the tool path;
simulating dynamics of the surgical tool in a virtual simulation based on the virtual constraints and the input from the force/torque sensor; and
commanding the manipulator to advance the surgical tool along the tool path based on the virtual simulation.

### Claim 12 (depends on 11)

The method of claim 11, wherein simulating dynamics of the surgical tool further comprises representing the surgical tool as a virtual rigid body having a virtual mass and by applying a constraint force to the virtual mass in the virtual simulation to yield a commanded pose, wherein the constraint force is based on the virtual constraints.

### Claim 13 (depends on 12)

The method of claim 12, comprising:
determining a target pose on the tool path based on the effective feed rate.

### Claim 14 (depends on 13)

The method of claim 13, comprising:
defining the virtual constraints with respect to the three degrees of freedom based on a distance between the commanded pose and the target pose.

### Claim 15 (depends on 11)

The method of claim 11, comprising:
defining one or more additional constraints associated with constraining an orientation of the surgical tool;
simulating dynamics of the surgical tool in the virtual simulation based on the virtual constraints, the one or more additional constraints, and the input from the force/torque sensor; and
commanding the manipulator to advance the surgical tool along the tool path based on the virtual simulation.

### Claim 16 (depends on 11)

The method of claim 11, comprising:
operating the manipulator in a guided-manual mode and a semi-autonomous mode;
utilizing the effective feed rate and define the virtual constraints in the guided-manual mode; and
in response to transitioning to the semi-autonomous mode from the guided-manual mode, calculating a transition path from a current position of a tool center point of the surgical tool to a last known point of the surgical tool on the tool path before transitioning from the semi-autonomous mode.

### Claim 17 (depends on 11)

The method of claim 11, comprising:
obtaining a virtual boundary for the surgical tool with the virtual boundary being a three-dimensional tube defining the tool path; and
defining the virtual constraints on movement of the surgical tool inside the three-dimensional tube and along the tool path, the virtual constraints being defined to constrain movement of the surgical tool to be along the tool path.

### Claim 18 (depends on 11)

The method of claim 11, comprising:
defining the virtual constraints as velocity constraints, wherein each of the velocity constraints comprises stiffness and damping parameters and one or more force limits and one or more activation limits.

### Claim 19 (depends on 11)

The method of claim 11, comprising:
determining a direction of movement to move the surgical tool along the tool path based on the calculated tangential force component.

### Claim 20 (depends on 11)

The method of claim 11, comprising:
defining an end constraint with respect to one degree of freedom tangential to the tool path to constrain the surgical tool to remain on the tool path by constraining movement beyond an end of the tool path.