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.