Welding assistance method for a robot device
A method for welding together two parts along a weld line using a welding system enabling an operator to remotely perform welding operations. The operator defines reference points on the parts to be welded and/or on the weld line to be followed. A general movement direction of the welding torch is defined from the reference points. A local frame of reference is defined relative to the general movement direction of the welding torch. The welding torch is automatically moved from a welding starting point in the general movement direction. A flow of movement instructions linked to actions of the operator on the human-machine interface is generated to move the welding torch away from the general movement direction to adapt a trajectory of the welding torch to an actual shape of the weld line. The welding torch is moved corresponding to the flow of instructions generated by the human-machine interface.
1 . A welding assistance method between two parts along a weld line using a welding system allowing an operator to carry out welding operations remotely, the welding system comprising:
a robotic device carrying a welding torch, said robotic device being associated with a robot coordinate frame;
a man-machine interface configured to generate movement instructions for moving the robotic device;
a controller configured to receive the movement instructions from the man-machine interface and to control the robotic device according to the movement instructions received via a communication link; and
the welding assistance method comprising:
defining, through the operator, reference points on at least one of: the parts to be welded and the weld line to be followed;
defining a general direction of movement of the welding torch from the reference points;
defining a local coordinate frame with respect to the general direction of movement of the welding torch;
automatically moving the welding torch from a welding initial point in the general direction of movement;
generating a flow of movement instructions linked to actions of the operator on the man-machine interface to move the welding torch away from the general direction of movement in order to adapt in real-time a trajectory of the welding torch to a real shape of the weld line;
processing, through the controller, the flow of movement instructions generated by the man-machine interface in order to deduce therefrom a desired speed vector or a desired position in the local coordinate frame; and
effectively moving the welding torch corresponding to the desired speed vector or to the desired position in the local coordinate frame.
2 . The method of claim 1 , wherein to ensure the effective movement of the torch, the method further comprises:
transposing the desired speed vector or the desired position in the robot coordinate frame;
determining, from coordinates of the desired speed vector or of the desired position in the robot coordinate frame, joint coordinates of the robotic device; and
effectively moving the welding torch according to the joint coordinates previously determined.
3 . The method of claim 1 , wherein the general direction of movement is a direction having a shape chosen from: a straight line, a circle or a portion of a circle, an oval shape or a portion of an oval, a polygon or a portion of a polygon, an intersection of two cylinders or an intersection portion of two cylinders, or a 2D or 3D curve.
4 . The method of claim 1 , wherein following the definition of the welding initial point and a welding end point, and a validation of a trajectory along a return trip, further comprising adjusting the position of the reference points, the welding initial point and the welding end point.
5 . The method of claim 1 , wherein a latency period between an actuation of the man-machine interface by the operator and an effective movement of the welding torch is less than 450 ms.
6 . The method of claim 1 , wherein the local coordinate frame comprises an XI-axis coincident with the general direction of movement of the welding torch, a Zl-axis corresponding to a projection of a direction of orientation of the welding torch in a plane perpendicular to the Xl-axis, and a Yl-axis perpendicular to the plane defined by the Xl-axis and the Zl-axis.
7 . The method of claim 6 , wherein the welding system further comprises a camera and a monitor to display an image of the weld line and the welding torch captured by the camera; and
wherein an axis of the camera coincides with the general direction of movement such that the image displayed by the monitor is situated in the Yl/Zl plane.
8 . The method of claim 6 , wherein with an automatic movement along the Xl-axis being imposed by the robotic device, the operator can adjust a movement of the welding torch via the man-machine interface, only along at least one of the Yl-axis and the Zl-axis.
9 . The method of claim 6 , wherein the weld line is a curved weld line, the local coordinate frame evolves along the curved weld line such that the Xl-axis remains tangent to the curved weld line.
10 . The method of claim 6 , further comprising controlling a speed of movement of the welding torch along the Xl-axis via the man-machine interface.
11 . The method of claim 10 , wherein the speed of movement is between a minimum value and a maximum value.
12 . The method of claim 1 , further comprising adjusting an angular orientation of the welding torch with respect to the weld line.
13 . The method of claim 1 , wherein the welding system further comprises a camera and a monitor to display an image of the weld line and the welding torch captured by the camera.
14 . The method of claim 1 , further comprising establishing communication with a welding generator to modify welding parameters from the man-machine interface and to display the welding parameters modified on the man-machine interface.
15 . The method of claim 1 , wherein a continuous pressing of a safety button of the man-machine interface is imposed during a phase of making a weld by the robotic device.
16 . The method of claim 1 , wherein a continuous pressing of a safety button of the man-machine interface is imposed during an adjustment phase of defining the reference points.
17 . The method of claim 1 , wherein the robotic device comprises a plurality of actuators mechanically mounted in series with respect to each other.
18 . The method of claim 1 , wherein the robotic device comprises a structure made of a lightweight material, the lightweight material being aluminum or a composite material.
19 . The method of claim 1 , wherein the robotic device comprises a base provided with a removable holder configured to fix the robotic device on or near the parts to be welded.