Robotic system for grasping objects

Patent metadata

Field	Value
Publication number	US-11007648-B2
Application number	US-201816120953-A
Country	US
Kind code	B2
Filing date	Sep 4, 2018
Priority date	Sep 5, 2017
Publication date	May 18, 2021
Grant date	May 18, 2021

Abstract

A method is provided for grasping randomly sized and randomly located objects. The method may include assigning a score associated with the likelihood of successfully grasping an object. Other features of the method may include orientation of the end effector, a reachability check, and crash recovery.

First claim

The invention claimed is:

1. A method of robotically grasping an object, comprising:
imaging a first area within a workspace of the robot, the workspace containing multiple objects of random sizes and random locations and comprising a ramped surface;
determining a first score for the first area, the first score corresponding to a likelihood that a first object is graspable;
grasping the first object if the first score is above a first threshold and moving the first object to an output station; and
moving one or more objects in the workspace to change a position of objects in the workspace without moving the one or more objects to the output station;
wherein the step of moving the one or more objects in the workspace comprises grasping one of the objects with an end effector of the robot, moving the end effector and the object upward along the ramped surface, and releasing the object from the end effector at a height on the ramped surface higher than where the object was grasped, the object sliding on the ramped surface after being released by the robot and thereby pushing into the objects in the workspace to move the one or more objects.

2. The method according to claim 1 , wherein prior to the step of moving the one or more objects in the workspace, if the first score is below the first threshold, the method further comprises:
imaging a second area within the workspace of the robot;
determining a second score for the second area, the second score corresponding to a likelihood that a second object is graspable; and
grasping the second object if the second score is above a second threshold and moving the second object to the output station.

3. The method according to claim 2 , wherein prior to the step of moving the one or more objects in the workspace, if the second score is below the second threshold, the method further comprises:
imaging a third area within the workspace of the robot;
determining a third score for the third area, the third score corresponding to a likelihood that a third object is graspable; and
grasping the third object if the third score is above a third threshold and moving the third object to the output station.

4. The method according to claim 3 , wherein the first threshold, the second threshold and the third threshold are the same.

5. The method according to claim 3 , wherein the step of moving the one or more objects in the workspace is performed if the third score is below the third threshold prior to moving an object in the workspace to the output station.

6. The method according to claim 5 , wherein the robot grasps the third object and moves the third object to perform the step of moving the one or more objects in the workspace.

7. The method according to claim 1 , wherein the step of moving the one or more objects in the workspace is performed if the first score is below the first threshold prior to moving an object in the workspace to the output station.

8. The method according to claim 7 , wherein the robot grasps the first object and moves the first object to perform the step of moving the one or more objects in the workspace if the first score is below the first threshold.

9. The method according to claim 1 , wherein the multiple objects in the workspace are rectangular shipping packages with each having at least one flat surface larger than edge surfaces, the first score corresponding to a likelihood that the at least one flat surface of a shipping package is graspable.

10. The method according to claim 1 , wherein the first object is grasped with one or more vacuum cups.

11. The method according to claim 1 , wherein the first object is separated from other objects on the output station.

12. The method according to claim 1 , wherein the end effector of the robot moves to the first object in the step of grasping the first object at a first speed, and the end effector moves to one of the objects in the step of moving the one or more objects in the workspace at a second speed, the second speed being slower than the first speed.

13. The method according to claim 1 , wherein the step of moving the one or more objects in the workspace comprises grasping one of the objects with the end effector of the robot, moving the object with the end effector, and releasing the object from the end effector while the end effector is moving, the object thereby being tossed to a new location in the workspace.

14. The method according to claim 13 , wherein the end effector is moving at an accelerating speed when the object is released from the end effector.

15. The method according to claim 1 , wherein an infeed conveyor is disposed at a top of the ramped surface, the multiple objects being fed into the workspace from the infeed conveyor at the top of the ramped surface.

16. The method according to claim 1 , wherein the step of grasping the first object comprises:
determining an orientation and a location of the first object using imaged surfaces of the first object;
determining motions of the robot based upon the orientation and location to grasp the first object with the end effector of the robot, wherein the motions include a rotation movement and the rotation movement is retained within a predefined angular range; and
moving the robot using the determined motions and grasping the first object.

17. The method according to claim 1 , wherein the step of grasping the first object comprises:
determining whether a pre-pick target for the first object is reachable by the robot;
determining whether a pick target for the first object is reachable by the robot; and
grasping the first object with the robot and moving the first object to the output station responsive to a determination that the pre-pick target and the pick target are reachable by the robot.

18. The method according to claim 1 , further comprising:
determining that a robotic control program being executed on a robotic controller to operate the robot has been stopped;
determining whether a cause of the stoppage is a motion supervision error;
requesting a new target object from a vision system; and
resuming normal robotic operation using the robotic control program.

19. The method according to claim 1 , further comprising:
performing an action with the robot by executing a robotic control program;
detecting a collision of the robot;
stopping the execution of the robot control program;
setting a crash flag;
requesting a new target object from a vision system; and
resuming normal robotic operation using the robotic control program.

20. A method of robotically grasping an object, comprising:
imaging a first area within a workspace of the robot, the workspace containing multiple objects of random sizes and random locations;
determining a first score for the first area, the first score corresponding to a likelihood that a first object is graspable;
grasping the first object if the first score is above a first threshold and moving the first object to an output station; and
moving one or more objects in the workspace to change a position of objects in the workspace without moving the one or more objects to the output station;
wherein the step of moving the one or more objects in the workspace comprises grasping one of the objects with an end effector of the robot, moving the object with the end effector, and releasing the object from the end effector while the end effector is moving, the object thereby being tossed to a new location in the workspace.

Assignees

• Abb Schweiz Ag

Inventors

• Wertenberger Steven
• Watson Thomas
• Sallee Matthew

Classifications

• B25J9/1676

  Avoiding collision or forbidden zones · CPC title

• B25J9/0093

  co-operating with conveyor means · CPC title

• B25J9/1697 Primary

  Vision controlled systems · CPC title

• G05B2219/40053

  Pick 3-D object from pile of objects · CPC title

• B65G47/52

  Devices for transferring articles or materials between conveyors i.e. discharging or feeding devices (loading or unloading by means not incorporated in, or not operatively associated with, conveyors B65G65/00; transfer of workpieces during metal rolling B21B41/00) · CPC title