Systems and methods for tracking a path using the null-space

Patent metadata

Field	Value
Publication number	US-9610689-B2
Application number	US-201615057073-A
Country	US
Kind code	B2
Filing date	Feb 29, 2016
Priority date	Sep 17, 1999
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

Devices, systems, and methods for providing a desired movement of one or more joints of a manipulator arm having a plurality of joints with redundant degrees of freedom while effecting commanded movement of a distal end effector of the manipulator. Methods include defining a constraint, such as a network of paths, within a joint space defined by the one or more joints and determining a movement of the plurality of joints within a null-space to track the constraints with the one or more joints. Methods may further include calculating a reconfiguration movement of the joints and modifying the constraints to coincide with a reconfigured position of the one or more joints. Various configurations for devices and systems utilizing such methods are provided herein.

First claim

What is claimed is:

1. A method for a manipulator arm, the manipulator arm comprising a movable distal portion that includes an end effector, a proximal portion coupled to a base, and a plurality of joints between the distal portion and the base, the plurality of joints having sufficient degrees of freedom to allow a range of differing joint states for a given state of the end effector, the method comprising:
defining a position-based constraint of one or more joints of the plurality of joints within a joint space of the plurality of joints, the position-based constraint including one or more paths corresponding to a desired movement of the one or more joints within the joint space of the plurality of joints;
receiving a manipulation command to move the end effector with a desired end-effector movement;
calculating an end-effector displacing movement of the plurality of joints to effect the desired end-effector movement, wherein calculating the end-effector displacing movement of the plurality of joints comprises calculating joint velocities of the plurality of joints from directions that correspond to the end effector moving;
calculating a tracking movement of the plurality of joints so as to move a position of the one or more joints of the plurality of joints towards the position-based constraint, wherein calculating the tracking movement of the plurality of joints comprises calculating joint velocities of the plurality of joints from directions that correspond to the end effector not moving; and
driving the plurality of joints according to the calculated movements so as to effect the end-effector displacing movement concurrently with the tracking movement.

2. The method of claim 1 , further comprising:
calculating values for a Jacobian of the manipulator arm, the joint velocities from directions that correspond to the end effector not moving being associated with a null space of the Jacobian, and the joint velocities from directions that correspond to the end effector moving being associated with a null-perpendicular space of the Jacobian.

3. The method of claim 1 , wherein a first path of the one or more paths of the position-based constraint has at least one dimension and is defined within a subspace of the joint space of the plurality of joints by at least two joints of the plurality of joints.

4. The method of claim 1 , wherein the one or more paths of the position-based constraint include a network of piecewise continuous paths within the joint space of the plurality of joints.

5. The method of claim 1 , wherein calculating the tracking movement comprises:
defining a potential field between a calculated position of the one or more joints of the plurality of joints and the one or more paths of the position-based constraint, wherein an increasing potential of the potential field corresponds to an increasing distance between the calculated position and the one or more paths;
determining from the potential field a potential between the calculated position and the one or more paths; and
calculating the tracking movement by using the potential to determine a direction from the calculated position towards the one or more paths.

6. The method of claim 1 , wherein calculating the tracking movement comprises:
determining a first movement of the plurality of joints within the joint space of the plurality of joints by evaluating a potential function of the one or more joints of the position-based constraint; and
determining the joint velocities of the plurality of joints for the tracking movement by projecting the first movement of the plurality of joints onto a null space of a Jacobian of the manipulator arm.

7. The method of claim 1 , wherein the distal portion of the manipulator arm includes an instrument holder that releasably supports a surgical instrument having an elongate shaft extending distally to the end effector, the shaft pivoting about a remote center of motion during surgery.

8. A system comprising:
a manipulator arm comprising a movable distal portion that includes an end effector, a proximal portion coupled to a base, and a plurality of joints between the distal portion and the base, the plurality of joints having sufficient degrees of freedom to allow a range of differing joint states for a given state of the end effector;
an input device for receiving a manipulation command to move the end effector with a desired end-effector movement;
one or more processors operably connected to the input device and the manipulator arm, the one or more processors being configured to perform operations including:
defining a position-based constraint of one or more joints of the plurality of joints within a joint space of the plurality of joints, the position-based constraint including one or more paths corresponding to a desired movement of the one or more joints within the joint space of the plurality of joints;
calculating an end-effector displacing movement of the plurality of joints to effect the desired end-effector movement, wherein calculating the end-effector displacing movement of the plurality of joints comprises calculating joint velocities of the plurality of joints from directions that correspond to the end effector moving;
calculating a tracking movement of the plurality of joints so as to move a position of the one or more joints of the plurality of joints towards the position-based constraint, wherein calculating the tracking movement of the plurality of joints comprises calculating joint velocities of the plurality of joints from directions that correspond to the end effector not moving; and
transmitting a command to the manipulator arm to drive the plurality of joints according to the calculated movements so as to effect the end-effector displacing movement concurrently with the tracking movement.

9. The system of claim 8 , wherein the operations further comprise:
calculating values for a Jacobian of the manipulator arm, the joint velocities from directions that correspond to the end effector not moving being associated with a null space of the Jacobian, and the joint velocities from directions that correspond to the end effector moving being associated with a null-perpendicular space of the Jacobian.

10. The system of claim 8 , wherein a first path of the one or more paths of the position-based constraint has at least one dimension and is defined within a subspace of the joint space of the plurality of joints by at least two joints of the plurality of joints.

11. The system of claim 8 , wherein the one or more paths of the position-based constraint include a network of piecewise continuous paths within the joint space of the plurality of joints.

12. The system of claim 8 , wherein calculating the tracking movement comprises:
defining a potential field between a calculated position of the one or more joints of the plurality of joints and the one or more paths of the position-based constraint, wherein an increasing potential of the potential field corresponds to an increasing distance between the calculated position and the one or more paths;
determining from the potential field a potential between the calculated position and the one or more paths; and
calculating the tracking movement by using the potential to determine a direction from the calculated position towards the one or more paths.

13. The system of claim 8 , wherein calculating the tracking movement comprises:
determining a first movement of the plurality of joints within the joint space of the plurality of joints by evaluating a potential function of the one or more joints of the position-based constraint; and
determining the joint velocities of the pluralit

Assignees

• Intuitive Surgical Operations

Inventors

• Swarup Nitish
• Hourtash Arjang M
• Mohr Paul W

Classifications

• G05B2219/40359

  Constraint, physical limitations · CPC title

• G05B2219/40339

  Avoid collision · CPC title

• B25J9/1643 Primary

  redundant control · CPC title

• A61B2034/742

  Joysticks · CPC title

• A61B2034/107

  Visualisation of planned trajectories or target regions · CPC title