Coordinated Motion Planning Of The Welding Robot And Positioner

Welding is a fundamental technology of modern industry and influences thequality of industrial products immediately. The welding robotic system canimprove the welding effciency, lower the human costs and obtain better weldingquality, so it is applied in the actual welding widely.Based on six degrees of freedom serial robot with a offset wrist and2-axispositioner, a welding robotic system has been set up in this paper. Because thetube-plate fillet weld, tube-tube and spiral line are common in the industrialproducts, this paper chooses them as main experiment objects. According tothose characteristics, corresponding mathematical models of weld-seam andtorch orientation were constructed. Geometric method and screw theory wereapplied comprehensively to study the inverse kinematic of robot. And accordingto the minimum displacements of joints, a better result was chosen. An easiermethod has been provided to get the deviation of jacobian matrix of our robotmodel. Considering the genetory characteristics of flat welding, an algorithm hasbeen given to realize the flat positions of weldpoints through the positioner.For the coordinated motion planning problem of the robotic system,poseture index of the torch, the manipuility index of robot and the stability indexof the motion have been set up according to the requirements of the weldingproduction. And two object functions were proposed based on the differentfocuses. The incorporation of multiple criteria control was implemented by theweighting method. The genetic algrithm has been applied to optimize the weldingpath for three typical weldseams of the industrial production. And the results hasbeen compared with other people’s. Because the motion of the robot andpostioner were more stable, the results indicated that our algrithm was correctand feasible. A good welding appearance could be gotten. Meanwhile,considering the higher demands on the manipuility of the robot in the weldingprocess, the manipuility function was elected as the object funcion and the othercriteria were elected as constraint condicions. The genetic algrithm has also beenapplied to optimize the above weldseams. The paths had better manipuility, butthe joint speed and acceleration fluctuated violently so that the motio n stabilitybecame worse. And a bad welding appearance would be obtained.