Motion Planning And Graphic Simulation Of Welding Robot And Positioner For Intersecting Welding Curve

Welding technology is an important manufacturing method which is widely used in industrial production to generate atomic bonding between materials and materials.In order to reduce the manpower requirement of welding and improve the efficiency and quality of welding production,more and more welding robots have been put into industrial production.According to the welding experience,when a series of welding spots which are discretized by welding seam are in the flat welding posture,that is,the normal vector of the welding spot is opposite to the gravity direction,and a better welding seam can be obtained by welding in such posture.Intersection curve welding seam is a common curve welding seam in industrial production.Aiming at this complex space welding seam,in order to enlarge the workspace of welding robot,improve the flexibility of robot for welding and avoid the singularities that may occur in the movement of the welding robot,so as to ensure the welding quality and efficiency,it's necessary to introduce the positioner into the welding robot to form a welding robot system.In this paper,the intersection curve is taken as the research object,aiming at the arbitrary welding spot in the flat welding posture,motion planning and graphical simulation of welding robot system are studied.Firstly,the coordinate system of welding seam and torch is defined and expressed mathematically.The description of welding seam is discretized into a series of welding spots by the idea of mathematical discretization,and a coordinate system is fixed at each welding spot.The description of welding coordinate system can be completed by the transformation matrix from welding coordinate system to workpiece coordinate system.However,the description of welding torch coordinate system can be realized by transforming operators through three welding torch attitude angles:working angle,walking angle and rotation angle.Aiming at the forward and inverse kinematics algorithm of welding robot system,this paper uses two different methods,D-H parameter method and screw method,to model the robot.In the D-H model,the inverse solution of the robot is based on the separation of pose and position of the robot,and the inverse transformation method is used to solve the problem.In the screw model,the inverse solution of robot is first to solve the joint angle₁ by using the geometric relationship,then to transform the joint angle₂ and₃ into two Paden-Kahan sub-problems 1,then to transform the joint angle₄ and₅ into a Paden-Kahan sub-problem 2,and finally to transform the joint angle₆ into a Paden-Kahan sub-problem 1.For multi-solution problems in inverse solutions,the shortest travel criterion is used to find a set of optimal solutions.In order to obtain the coordinate trajectory of the welding robot and the positioner,the coordinate system of the welding robot system is decoupled from the welding seam coordinate system in the closed chain,and the preliminary trajectory panning is obtained.The B-spline interpolation algorithm is used to smooth the joint motion space trajectory of the welding robot system.The Jacobian matrix is solved by differential transformation method,and the conditions for the joint angle of welding robot to be satisfied when the welding robot is in singular shape are finally calculated.The collision detection of welding torch and weldment is carried out by using the method of bounding box and triangular surface of weldment.Finally,the final trajectory planning is completed.Finally,through the combination of VC++and OpenGL for programming,the three-dimensional model of the robot system is established by using 3DS MAX,and the model is imported into OpenGL through Assimp library,and the realistic rendering is carried out.The visual simulation in off-line programming is realized by the transformation of model matrix in OpenGL.