Complex Framework Structure Robot Collision-free Welding Path And Trajectory Planning Studies

With the development of welding automation technology, the welding robots, as the key equipment in welding automation, play an increasingly important role. Spot welding robot is one kind of the welding robot, and the study of its path and trajectory planning is less than other kind of robot in its early application because of its simple task. But with the development of the manufacturing industry, especially the automotive industry, the welding robots are widely used and the welding tasks are becoming more and more complex, so it is necessary to study on the welding path and trajectory of the spot welding robots with complex task.This paper studied collision-free welding path and trajectory planning method of the welding robot which of the welding gun can be changed and the weldments have complicated frame structure, based on the welding process of side-frame outer panel. The welding sequence optimization, complicated frame modeling, obstacle avoidance strategy of collision-free path and path planning technology of spot welding robot have been studied detailed. Otherwise, the suggested planning methods are demonstrated with examples and simulation. The main contents of the article are as follows:(1) Using ant colony algorithm to Optimized the welding sequence of the grouped solder joints of the side-frame outer panel, based on the analysis of the spot welding process. The effect of the welding process on the welding sequence is considered in that method which is more practical engineering value.(2) The structural characteristics of complicated frame weldments was analyzed by studying the side-frame outer panel. Wireframe model is determined to model for the complicated frame. Features of frame can be adequately expressed by this model which has fewer redundancy and lower model data completed to the past polyhedral model. This modeling method is beneficial to improve the efficiency of follow-up obstacle avoidance operation.(3) Taking C-type gun as an example, this paper analyzed the effect of the structure and kinematic characteristics of the welding gun on the collision detection and treatment. The effect of the processing parameters of the collision on the collision treatment was discussed based on the wire-frame model of the side-frame outer panel. The obstacle avoidance strategy was finally established which consists of two parts:final basic obstacle avoidance processing and dynamic obstacle avoidance processing. The strategy is based on the wire-frame model of the side-frame outer panel and the key parameter of the obstacle avoidance is expressed with space dynamic vector which brings simple calculation, high efficiency and adaptive ability for the change of welding gun.(4) According to the characteristics of the spot welding robot and combining with the path planning methods of general robot, the paper ultimately determine the path planning methods of using Cartesian space for the welding trajectories and path planning methods of combining polynomial interpolation in the joint space with arc interpolation in the Cartesian space for the non-welding trajectories.(5) According to the planning method of this paper, Visual Basic is used to compile the planning software and to complete the planning of collision-free welding path and trajectory of the side-frame outer panel. The welding trajectory of side-frame outer panel is simulated with the off-line programming software:Robot Studio, which verifies the feasibility and availability of the planning method.