Design And Research On Simulation System Of A Welding Robot Workstation

With the development of the society, the labor cost is higher and higher and the demand for industrial robots is also increasing. The proportion of welding robot is the most in the application of industrial robots. In addition, the robot simulation system is a reliable method for the research and application of the actual robot system, which has great significance. So this paper is to design and develop a set of simulation system which is suitable for welding robot workstation and study the key technologies.In this paper, the D-H parameters of the robot are obtained by the welding robot MOTOMAN-MH12. The forward kinematics equation of the robot is derived from the D-H parameters and the inverse kinematics solution is also analyzed.As the welding quality is related to the welding parameters, so the welding parameters are planned. Meanwhile, the planning of the straight bead and curve welding seam is analyzed. The planning of the straight bead and curve welding seam are divided into the planning which provides welding surface information and the planning which does not provides welding surface information. Considering the mathematical expressions of the planning which does not provides welding surface information are varied, we extract discrete point coordinates and fit into Newton interpolation polynomial, and then carry out the trajectory planning. Considering the poor quality of the welding method is not downward welding or Ship welding, we study the coordinated trajectory planning of robot and positioner. In order to detect whether there is a collision in the simulation system, we present collision detection algorithm based on distance calculation and collision detection algorithm based on intersection judgment. These two kinds of algorithms are used to detect internal collisions and external collisions of the robot. The collision detection algorithm based on intersection judgment has large computation. In addition, it can be used to detect the geometric model which is complex and the applicability is wide. Considering the weldment produces a considerable residual deformation in the welding process because of the instantaneous heat energy.For a comprehensive understanding of the distribution of welding deformation, we analyze the welding deformation. We validate the numerical simulation results of straight bead and reduce welding deformation according to the numerical simulation results. Finally, in order to improve the programming efficiency and achieve the best path planning, the off-line programming is developed through the simulation system. The simulation of trajectory planning and welding experiments of circular weld and intersecting lines weld are carried out. The results show circular weld meets the welding quality requirements and the quality of downhill welding is better than uphill welding in the intersecting lines weld. The welding quality of intersecting lines weld can be improved by coordinated welding of positioner.