Adaptive remote laser welding system with triangulation feedback

Namen doktorskega dela je razviti adaptivni krmilni modul za visoko zmogljive laserske daljinske sisteme. Ti sistemi potrebujejo natančno določitev varilne trajektorije in kontrolo laserske moči za dosego želene kvalitete obdelave. Omenjeno zajema sočasno sinhronizacijo gibanja robotske roke, laserskega snopa po trajektoriji relativno poljubnih oblik in ustreznega spreminjanja laserske moči. Ročno učenje laserskih daljinskih sistemov je dolgotrajno in nenatančno zaradi majhnih premerov laserskega snopa v gorišču kot tudi netočne geometrije obdelovancev, nenatančnega vpetja in deformacij med varjenjem. Razviti nadzorni modul opisane probleme rešuje z uporabo triangulacijske povratne zanke in soosnega osvetljevanja območja interakcije za natančno sprotno določitev 3D lokacije varilne trajektorije in laserskega snopa ter velikosti območja interakcije. Pri tem sta potrebna dva načina umeritve, ki zajemata pozicijsko umestitev in umeritev modula v prostoru ter določitev relacije med močjo varjenja, hitrostjo varjenja ter globino prevaritve. V rezultatih smo primerjali različne načine krmiljenja pozicije in moči laserskega snopa. Pokazali smo, da lahko dosežemo pozicijsko točnost snopa z natančnostjo pod 0,05 mm, kar je štirikrat boljše od človeške ločljivosti očesa. Z istim modulom lahko s krmiljenjem moči laserja zagotovimo konstantno prevaritev s standardno deviacijo pod 0,1 mm ter sočasno zmanjšamo pojav izbruha plazme.The proposed PhD thesis aims to develop an adaptive control module for high-performance remote-laser welding systems. These systems require precise determination of the weld path and control of the laser beam power to achieve the desired weld quality, which involves simultaneous synchronization of the movement of the robotic arm, the laser beam along a relatively arbitrarily shaped trajectory, and the corresponding change of laser power. Manual teaching of remote-laser welding systems is a tedious and inaccurate process, due to the narrow diameter of the laser beam at the focal position, as well as factors such as inexact workpiece geometry, unreliable clamping, and deformations that occur during welding. The proposed control module addresses these issues by employing a triangulation feedback control loop and coaxial structured illumination of the interaction zone to determine accurately and simultaneously the 3D position of the weld path and laser beam, and the size of the interaction zone. Two calibration methods are implemented for this control method, including positioning the control module in space and determining the relationship between welding power, speed, and penetration depth. In the results, we compared different ways to control the position and power of the laser beam. Experimental results demonstrate beam position accuracy of less than 0.05 mm, which is four times better than the resolution of the human eye. With the same module, by controlling the laser power, we can ensure a constant penetration depth with a standard deviation of less than 0.1 mm, while also reducing the occurrence of plasma bursts