Granted Patent B1

US 10,335,947 · App. 16/252,383 · Granted Jul 2, 2019

Inventors: Rosen Diankov (Tokyo, JP); Huan Liu (Tokyo, JP); Denys Kanunikov (Tokyo, JP)

Assignee: MUJIN, Inc.

B25J9/1664B25J9/1633B25J9/1674B65G61/00

Abstract

Claims (75)

1. A method for operating a transfer robot including a gripper for gripping a target object and a robotic arm for maneuvering the gripper, the method comprising:

calculating a base motion plan, wherein the base motion plan includes a first set of actuator commands, actuator settings, or a combination thereof, that is configured to operate the robotic arm and the gripper to transfer the target object from a start location to a task location;

tracking a current location of the target object while executing the base motion plan;

receiving a contact measure while executing the base motion plan, wherein the contact measure represents an amount of grip of the gripper on the target object measured by a contact sensor after initiating horizontal transfer of the target object;

determining that the contact measure fails to satisfy a transfer grip threshold; and

calculating an adjusted motion plan that deviates from the base motion plan based on the determination, wherein the adjusted motion plan includes a second set of actuator commands, actuator settings, or a combination thereof corresponding to a controlled drop including:

selecting a drop area based on the current location, wherein the drop area is selected from a source drop area, a destination drop area, a transit drop area, or a combination thereof,

calculating an adjusted drop location in the selected drop area, wherein the adjusted drop location is calculated after the contact measure is determined to be below the transfer grip threshold, and

calculating an adjusted motion plan to transfer the target object from the current location to the adjusted drop location, wherein the adjusted drop location is different from the task location.

2. The method of claim 1 , further comprising:

tracking an orientation of the gripper while executing the base motion plan; and

adjusting the contact measure based on the orientation to account for a directional relationship between a sensing direction for the contact sensor and gravitational force applied to the target object according to the orientation.

3. The method of claim 1 , wherein selecting the drop area includes:

determining that the current location is outside of the source drop area and the destination drop area; and

selecting the transit drop area based on the determination to intentionally place the target object therein instead of the task location.

4. The method of claim 1 , wherein selecting the drop area includes

determining that the current location is within the source drop area, wherein the source drop area is associated with boundaries of a container or a pallet including the start location; and

selecting the source drop area based on the determination to intentionally place the target object therein.

5. The method of claim 1 , wherein selecting the drop area includes:

determining that the current location is within the destination drop area, wherein the destination drop area is associated with boundaries of a container or a pallet including the task location; and

selecting the destination drop area based on the determination to intentionally place the target object therein.

6. The method of claim 1 , wherein:

the adjusted drop location is different from both the start location and the task location; and

the adjusted motion plan includes actuator commands, actuator settings, or a combination thereof to:

transfer the target object to the adjusted drop location from the current location, and

release the target object from the gripper at the adjusted drop location to intentionally place the target object at the adjusted drop location.

7. The method of claim 1 , wherein the adjusted motion plan includes actuator commands, actuator settings, or a combination thereof to regrip the target object with the gripper after executing the controlled drop.

8. The method of claim 1 , further comprising:

cancelling remaining actions of the base motion plan after executing the controlled drop;

determining a new target object; and

calculating a new base motion plan to transfer the new target object.

9. The method of claim 1 , wherein the transfer grip threshold is lesser than an initial grip threshold associated with initially gripping the target object before horizontally transferring the target object.

10. The method of claim 1 , wherein receiving the contact measure includes receiving a measurement of a force, a torque, a pressure, or a combination thereof that corresponds to the amount of grip, and wherein the measurements are made for one or more locations on the robotic arm, one or more locations on the gripper, or a combination thereof.

11. A method for operating a transfer robot including a gripper for gripping a target object and a robotic arm for maneuvering the gripper, the method comprising:

calculating a base motion plan, wherein the base motion plan includes a sequence of actuator commands, actuator settings, or a combination thereof, that is configured to operate the robotic arm and the gripper to transfer the target object from a start location to a task location;

receiving a contact measure while executing the base motion plan, wherein the contact measure represents an amount of grip of the gripper on the target object measured by a contact sensor after gripping the target object and before initiating horizontal transfer of the target object;

determining that the contact measure fails to satisfy an initial grip threshold;

generating regrip commands, regrip settings, or a combination thereof based on the determination, wherein the generated regrip commands, regrip settings, or a combination thereof deviate from the base motion plan to regrip the target object.

12. The method of claim 11 , further comprising:

executing a first set of actions in the base motion plan, including placing the gripper about the start location and initially gripping the target object with the gripper;

wherein:

receiving the contact measure includes receiving the contact measure determined after initially gripping the target object; and

the generated actuator commands, actuator settings, or a combination thereof are configured to operate the robotic arm, the gripper, or a combination thereof to:

release the target object from the gripper when the contact measure is below the initial grip threshold after executing the first set of actions, and

regrip the target object with the gripper after releasing the target object.

13. The method of claim 12 , further comprising generating position adjustment commands, position adjustment settings, or a combination thereof to adjust a position of the gripper after releasing the target object and before regripping the target object.

14. The method of claim 13 , further comprising:

receiving a regrip contact measure after regripping the target object;

determining that the regrip contact measure satisfies the initial grip threshold; and

adjusting the base motion plan based on the determination, wherein the base motion plan is adjusted according to the generated position adjustment commands, position adjustment settings, or a combination thereof to transfer the target object from the adjusted position of the gripper to the task location.

15. The method of claim 11 , further comprising:

pausing execution of the base motion plan when the contact measure fails to satisfy the initial grip threshold; and

receiving a regrip contact measure after regripping the target object; and

resuming execution of the base motion plan when the regrip contact measure satisfies the initial grip threshold.

16. The method of claim 11 , further comprising:

pausing execution of the base motion plan when the contact measure fails to satisfy the initial grip threshold;

determining that an iteration count exceeds a threshold based on iteratively:

incrementing the iteration count after regripping the target object,

receiving a regrip contact measure after regripping the target object,

determining that the regrip contact measure fails to satisfy an initial grip threshold, and

regenerating the regrip commands, regrip settings, or a combination to regrip the target object; and

generating a solicitation for an operator input when the iteration count exceeds the threshold.

17. The method of claim 11 , wherein the contact measure represents a quantity, a location, or a combination thereof of suction cups of the gripper contacting a surface of the target object and holding a vacuum condition therein.

18. The method of claim 11 , wherein the contact measure corresponds to a shift in the target object relative to jaws of the gripper that are configured to apply compressing forces on opposing points of the target object.

19. A tangible, non-transient computer-readable medium having processor instructions stored thereon that, when executed by a robotic system via one or more processors thereof, cause the robotic system to:

calculate a base motion plan, wherein the base motion plan includes a first set of actuator commands, actuator settings, or a combination thereof, that is configured to operate a robotic arm and a gripper to transfer a target object from a start location to a task location;

receive a contact measure while executing the base motion plan, wherein the contact measure represents an amount of grip of the gripper on the target object measured by a contact sensor;

determine that the contact measure fails to satisfy a threshold;

track a progress of executing the base motion plan, wherein the progress is associated with a horizontal transfer of the target object; and

selectively generate a second set of actuator commands, actuator settings, or a combination thereof based on the determination and the progress for operating the robotic arm, the gripper, or a combination thereof to deviate from the base motion plan and execute one or more response actions not included in the base motion plan.

20. The tangible, non-transient computer-readable medium of claim 19 further comprising:

instructions to track a current location of the target object while executing the base motion plan; and

instructions to determine that the progress corresponds to execution of the horizontal transfer;

wherein instructions to selectively generate includes:

instructions to generate the second set according to the current location based on the progress determination, wherein the second set corresponds to a controlled drop for intentionally placing the target object at a location different from the task location.

Assignments (1)

Cited By (13)

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