Automatic teaching of a robotic remote laser 3D processing system based on an integrated laser-triangulation profilometry

Abstract

Original scientific paper One of the key challenges in robotic remote laser 3D processing (RL3DP) is to achieve high accuracy for the laser's working trajectory relative to the features of the workpiece. This paper presents a novel RL3DP system with an automatic 3D teaching functionality for a precise and rapid determination of the working trajectory which comprises a robot manipulator, 3D scanning head, fibre laser and an off-axis positioned camera. The 3D measurement is based on laser triangulation with laser-stripe illumination using the laser's pilot beam and scanning head. The experimental results show that the system has a precision better than 70 µm and 120 µm along lateral and vertical direction respectively inside the measuring range of 100 × 100 mm. The teaching time is 30-times shorter compared to a visual teaching procedure. Therefore, such a system can lead to large cost reductions for modern production lines that have constant changes to the products' geometries and functionalities. Keywords: edge detection; laser triangulation; remote laser processing; robot teaching; three-dimensional measurement Automatsko učenje robotskih laserskih daljinskih 3D obradnih sustava na osnovu laserske triangulacijeIzvorni znanstveni članak Jedan od bitnih izazova u daljinskoj laserskoj 3D obradi (RL3DP) je postizanje visoke točnosti jer laser radi po rubovima predmeta koji obrađuje. Ovaj rad prikazuje novi RL3DP sustav s automatskom 3D nastavnom funkcionalnošću radi točnog i brzog određivanja prijenosa detektiranih rubova koje obrađuje robot sa 3D skenerom, fiber laserom i izvan aksijalno pozicioniranom kamerom. 3D skeniranje se bazira na laserskoj triangulaciji sa pilotskom laserskom trakom. Eksperimentalni rezultati pokazuju da sustav ima preciznost bolju od 70 µm i 120 µm u bočnom i vertikalnom smjeru u mjernom području od 100 × 100 mm. Vrijeme učenja je 30-puta kraće u odnosu na vizualni postupak. Stoga, takav sustav može značajno smanjiti troškove obrade sa modernim proizvodnim sistemima koji se moraju prilagođavati stalnim promjenama geometrije i funkcionalnosti proizvoda.

Automatic Calibration of the Adaptive 3D Scanner-Based Robot Welding System

“…Robotic welding is an important production technology that significantly increases the precision and efficiency of welding in numerous fields of industry ( Shimon et al, 2020 ). Workpiece complexity and small series of products are driving the development of this technology to shorten the programming time of the welding paths and enable in-line robot movement adaptation due to various influences, such as deviations between a CAD model and a real part, or thermal distortions of the workpiece ( Jezeršek et al, 2017 ; Kos et al, 2019 ). A promising solution to these issues is the integration of a laser profilometer onto the robot arm, which measures the shape of the workpiece in the vicinity of the weld path and corrects the robot movement accordingly.…”

“…A simple measurement principle, usually based on the laser triangulation principle ( Dorsch et al, 1994 ), offers a compact and robust design, enabling their wide application. In addition to adaptive robotic welding ( Hatwig et al, 2010 ; Jezeršek et al, 2017 ; Kos et al, 2019 ; Lee et al, 2020 ), other types of adaptive machining can be performed efficiently, such as milling ( Pérez et al, 2016 ) and deburring ( Kosler et al, 2016 ).…”

Remote laser welding with in-line adaptive 3D seam tracking

“…We can see the rise of remote laser welding applications in many fields such as automotive, electronics, and appliance industry where new and thinner materials are being used [1][2][3]. A demand is also seen in the field of monitoring and controlling such a process in order to achieve a better weld quality [4][5][6].…”