US 12,296,485 B2
Robot arm with adaptive three-dimensional boundary in free-drive
Jacob Gregers Hansen, Kolding (DK)
Assigned to Universal Robots A/S, Odense S. (DK)
Appl. No. 17/770,896
Filed by Universal Robots A/S, Odense S. (DK)
PCT Filed Oct. 9, 2020, PCT No. PCT/DK2020/050285
§ 371(c)(1), (2) Date Apr. 21, 2022,
PCT Pub. No. WO2021/078346, PCT Pub. Date Apr. 29, 2021.
Claims priority of application No. 2019 01239 (DK), filed on Oct. 22, 2019.
Prior Publication US 2022/0379468 A1, Dec. 1, 2022
Int. Cl. B25J 9/16 (2006.01)
CPC B25J 9/1641 (2013.01) 20 Claims
OG exemplary drawing
 
1. A robot controller for controlling a robotic arm, the robot controller for switching the robotic arm from a first mode of operation to a free-drive mode of operation in response to a free-drive mode signal, where, in the free-drive mode of operation, the robot controller is configured to perform operations comprising:
keeping the robotic arm in a posture that is static when only gravity acts on the robotic arm;
allowing a change in the posture of the robotic arm when an external force different from gravity is applied to the robotic arm;
monitoring a value of at least one parameter based on a signal of at least one sensor associated with a joint of the robotic arm;
comparing the value of the at least one parameter to at least one threshold value;
keeping the robotic arm in the free-drive mode of operation when the value of the at least one parameter does not exceed the at least one threshold value during a free-drive safety period;
wherein the at least one threshold value is based on a virtual three-dimensional geometric shape surrounding a part of the robotic arm;
wherein the free-drive safety period comprises a time period within which at least part of the robotic arm is allowed to move within the virtual three-dimensional geometric shape without creating a hazard; and
redefining the virtual three-dimensional geometric shape following expiration of the free-drive safety period and when the value of the at least one parameter has not exceeded the virtual three-dimensional geometric shape during the free-drive safety period.