Microvector control for edge and joint following
AssigneeGeneral Electric Company
InventorsAllen W. Case, Jr., Carl G. Ringwall, Michael L. Pollick
Life of this patent
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Abstract
An industrial robot is controlled to move by increments and approximately track an edge or a joint. A structured light pattern such as two parallel light bars is projected onto the workpiece and the scene is imaged by a visual sensor. Information derived from the image is used to compute move vectors. The navigation algorithm is based on extracting and computing the next move vector from the visual scene while the current move vector is being executed. The positioning system of an arc welding robot approximately follows the joint to be welded; the computed microvectors specify the direction and distance the positioning system moves.
Claims12
A method of controlling an arc welding torch and positioning system to track a joint in a workpiece to be welded, said arc welding torch having a light projector and an integral puddle view optical system, comprising the steps of:
- during the welding operation projecting a structured light pattern onto said workpieces and joint close to the weld puddle and producing images thereof with said integral optical system that are transmitted to a video camera and hence to a controller;
- computing a first move microvector from known positioning system parameters;
- capturing a first image and executing said first move while computing a second move microvector using parameters determined from said first image and from said positioning system;
- capturing a second image and executing said second move while computing a third move microvector using parameters determined from said second image and from said positioning system;
- said moves causing said positioning system to approximately follow said joint.
A method of controlling an industrial robot to move by increments to track at least one edge on a workpiece comprising the steps of:
- projecting a structured light pattern onto the workpiece intersecting and approximately perpendicular to said edge;
- producing images of the foregoing scene with an otpical lens system that are relayed to a controller;
- computing a first move microvector from robot parameters;
- capturing a first image and executing said first move while computing a second move microvector from parameters derived from said first image and robot;
- and
- capturing a second image and executing said second move while computing a third move microvector from parameters derived from said second image and robot;
- said moves causing said robot to approximately follow said edge.
A method of controlling the positioning system of a welding robot, which has a rotational axis and a vision sensor, to track a joint in a workpiece, comprising the steps of:
- during the welding operation projecting a structured light pattern onto said workpiece approximately perpendicular to said joint and close to the weld puddle;
- viewing the foregoing scene with said vision sensor and sequentially capturing a plurality of images of said weld puddle, joint and structured light pattern that are transferred to a controller;
- and
- executing move vectors specifying the direction and distance for said positioning system to move by increments to approximately follow said joint;
- each move vector being computed from parameters extracted from one image and obtained from said positioning system;
- the next move vector being extracted and computed while the current move vector is executed.
Dependencies are inferred from the claim text.