TOOL CALIBRATION FOR MANUFACTURING ROBOTS
A method for calibrating a tool center point (TCP) of a robotic welding system. The method includes receiving a plurality of images captured from a plurality of image sensors of the robotic welding system, the plurality of images containing at least a portion of a protrusion extending from a tip of a weldhead of the robotic welding system, and identifying by a controller of the robotic welding system the protrusion extending from the weldhead in the plurality of images. The method additionally includes defining by the controller a longitudinal axis of the protrusion based on the protrusion identified in the plurality of images, and identifying by the controller a location in three-dimensional (3D) space of the weldhead based on the protrusion identified in the plurality of images and the defined longitudinal axis of the protrusion.
1 . A method for calibrating a tool center point (TCP) of a robotic welding system, the method comprising:
(a) receiving a plurality of images captured from a plurality of image sensors of the robotic welding system, the plurality of images containing at least a portion of a protrusion extending from a tip of a weldhead of the robotic welding system;
(b) identifying by a controller of the robotic welding system the protrusion extending from the weldhead in the plurality of images;
(c) defining by the controller a longitudinal axis of the protrusion based on the protrusion identified in the plurality of images; and
(d) identifying by the controller a location in three-dimensional (3D) space of the weldhead based on the protrusion identified in the plurality of images and the defined longitudinal axis of the protrusion.
2 . The method of claim 1 , wherein the plurality of image sensors comprises a pair of cameras arranged stereoscopically in relation to the weldhead.
3 . The method of claim 1 , wherein (c) comprises identifying a trajectory in 3D space of the longitudinal axis of the protrusion.
4 . The method of claim 1 , wherein the protrusion comprises a welding wire.
5 . The method of claim 1 , wherein (b) comprises:
(b1) annotating at least one of the plurality of images to indicate a base of the protrusion and a tip of the protrusion located opposite the base of the protrusion identified in the plurality of images.
6 . The method of claim 5 , wherein (c) comprises:
(c1) defining a first plane in a first image of the plurality of plurality of images based on the annotated base of the protrusion;
(c2) defining a second plane in a second image of the plurality of images based on the annotated tip of the protrusion; and
(c3) intersecting the first plane with the second plane to define the longitudinal axis of the protrusion.
7 . The method of claim 1 , wherein (d) comprises identifying the location in 3D space of the weldhead based on a first projection of the protrusion captured in a first image of the plurality of images, a second projection of the protrusion captured in a second image of the plurality of images that is different from the first image, and on a known length extending between a base of the protrusion and a tip of the protrusion.
8 . The method of claim 1 , wherein (d) comprises:
(d1) triangulating a location in 3D space of a tip of the protrusion based on a first projection of a tip of the protrusion captured in a first image of the plurality of images and a second projection of the tip of the protrusion captured in a second image of the plurality of images that is different from the first image; and
(d2) identifying the location of a tip of the weldhead based on the location in 3D space of the tip of the protrusion and on a known length extending between a base of the protrusion and a tip of the protrusion.
9 . The method of claim 1 , wherein (d) comprises identifying a pose in 3D space of the weldhead.
10 . The method of claim 1 , wherein the plurality of image sensors comprises at least a portion of a local sensor unit or a global sensor unit of the robotic welding system.
11 . A robotic welding system for welding a part, the system comprising:
a fixture for holding the part to be welded;
a robot extending between a base and a terminal end;
a weldhead coupled to the terminal end of the robot, wherein the weldhead receives a protrusion;
a sensor unit comprising a plurality of image sensors arranged whereby at least a portion of the weldhead is within a field of view of each of the plurality of image sensors; and
a controller in signal communication with the sensor unit, wherein the controller is configured to:
receive a plurality of images captured from a plurality of image sensors of the robotic welding system, the plurality of images containing at least a portion of a protrusion extending from a tip of a weldhead of the robotic welding system;
identify the protrusion extending from the weldhead in the plurality of images;
define a longitudinal axis of the protrusion based on the protrusion identified in the plurality of images; and
identify a location in three-dimensional (3D) space of the weldhead based on the protrusion identified in the plurality of images and the defined longitudinal axis of the protrusion.
12 . The system of claim 11 , wherein the controller is configured to:
annotate at least one of the plurality of images to indicate a base of the protrusion and a tip of the protrusion located opposite the base of the protrusion identified in the plurality of images.
13 . The system of claim 12 , wherein the controller is configured to:
define a first plane in a first image of the plurality of plurality of images based on the annotated base of the protrusion;
define a second plane in a second image of the plurality of images based on the annotated tip of the protrusion; and
intersect the first plane with the second plane to define the longitudinal axis of the protrusion.
14 . The system of claim 11 , wherein the controller is configured to:
identify the location in 3D space of the weldhead based on a first projection of the protrusion captured in a first image of the plurality of images, a second projection of the protrusion captured in a second image of the plurality of images that is different from the first image, and on a known length extending between a base of the protrusion and a tip of the protrusion.
15 . The system of claim 11 , wherein the controller is configured to:
triangulate a location in 3D space of a tip of the protrusion based on a first projection of a tip of the protrusion captured in a first image of the plurality of images and a second projection of the tip of the protrusion captured in a second image of the plurality of images that is different from the first image; and
identify the location of a tip of the weldhead based on the location in 3D space of the tip of the protrusion and on a known length extending between a base of the protrusion and a tip of the protrusion.
16 . The system of claim 11 , wherein the plurality of image sensors comprises a pair of cameras arranged stereoscopically in relation to the weldhead.
17 . The system of claim 11 , wherein the controller is configured to:
identify a pose in 3D space of the weldhead based on the protrusion identified in the plurality of images and the defined longitudinal axis of the protrusion.
18 . The system of claim 11 , wherein the protrusion comprises a welding wire.
19 . A system for calibrating a tool center point (TCP) of a robotic welding system, the system comprising:
a processor;
a non-transitory memory; and
an application stored in the non-transitory memory that, when executed by the processor:
receives a plurality of images captured from a plurality of image sensors of the robotic welding system, the plurality of images containing at least a portion of a protrusion extending from a tip of a weldhead of the robotic welding system;
identifies the protrusion extending from the weldhead in the plurality of images;
defines a longitudinal axis of the protrusion based on the protrusion identified in the plurality of images; and
identifies a location in three-dimensional (3D) space of the weldhead based on the protrusion identified in the plurality of images and the defined longitudinal axis of the protrusion.
20 . The system of claim 19 , wherein the application, when executed by the processor:
annotates at least one of the plurality of images to indicate a base of the protrusion and a tip of the protrusion located opposite the base of the protrusion identified in the plurality of images.
21 . The system of claim 20 , wherein the application, when executed by the processor:
defines a first plane in a first image of the plurality of plurality of images based on the annotated base of the protrusion;
defines a second plane in a second image of the plurality of images based on the annotated tip of the protrusion; and
intersects the first plane with the second plane to define the longitudinal axis of the protrusion.
22 . The system of claim 19 , wherein the application, when executed by the processor:
triangulates a location in 3D space of a tip of the protrusion based on a first projection of a tip of the protrusion captured in a first image of the plurality of images and a second projection of the tip of the protrusion captured in a second image of the plurality of images that is different from the first image; and
identifies the location of a tip of the weldhead based on the location in 3D space of the tip of the protrusion and on a known length extending between a base of the protrusion and a tip of the protrusion.
23 . The system of claim 19 , wherein the application, when executed by the processor:
identifies a location in three-dimensional (3D) space of the weldhead based on the protrusion identified in the plurality of images and the defined longitudinal axis of the protrusion.