The Type And Structural Optimization Of All Position Welding Robots Of Intersecting Pipes

The welding of sphere tanks, oil tanks, and pipelines is one of the most common tasks in industries like petrochemicals, boilers, and shipbuilding. The spatial curve created by intersecting pipes is very hard to be dealt with by traditional welding robots. New welding robots of intersecting pipes includes climbing type robot, electromagnetic sticky robot, and cylinder type robot with new wrist structure.A condition number index based on global performance is proposed in this paper to conduct structural parameter optimization. During manipulation task, the higher the condition number index is, the lower the motor speed becomes. During the task of welding of intersecting pipes, the low speed of the welding gun causes the motor speed to become too slow to be controlled. Against the traditional interpretation of condition number, a new method is proposed to reduce the dexterity of robot in order to increase the motor speed.A new centering wrist structure for the cylinder type welding robot is constructed to achieve the decoupling between position and pose. The new centering wrist structure is consisted of a rod and a curved rail. During the adjustment of pose, the position of the end-effector can be unchanged.The program for the simulation of the structural parameter optimization based on higher condition number index is conducted in MATLAB. The interference index and compactness index are also considered in the process. The concept of the interference avoidance is defined, the mathematical model is constructed, and the structural parameter optimization of different types is conducted.The practicality of this new method is testified by 3D models. The measurements of models are also consistent to the computational result of interference index and compactness index.Based on the former research, the cylinder type robot is confirmed to be the best structural type. Although the motion range is limited by the special centering wrist structure, the advantage of this new type is far more obvious:the performance of motors is improved; the decoupling of structures makes modular design become possible; the adjustment of structure enable the robot to be suitable for more tasks.