Trajectory Planning And Contouring Motion Control Of3P3R Arc Welding Robots

To meet the demand of space-complex arc welding task, as well as lower the cost of specialized welding facility, a kind of3P3R arc welding robots has been developed. This robot adopts prismatic joints to determine its motion position and revolute joints to the posture, which can also be used to spray and burring fields with the actuator changed. Based on the work of robots parameter designe, driving system selection and the machine assembling, the kinematics positive and inverse solution have been worked out with D-H coordinates transfering method. Besides, the robots kinetics simulation model has been established as to carry on research of trajectory planning with SimMechanics based on MATLAB/Simulink. To make up the shortage of none coupling control of the3P3R robots contouring motion control system and improve the contouring tracking precision, the space contour error estimation model has been built up. Based on the model,various-gain cross coupling controller has been designed which aims at the contour error directly. The result indicats that the contour error has been decreased by38.8%. Finally experiments of trajectory planning and contouring motion control have been carried out based on the MATLAB/xPC real-time control system.The first charpter of the paper points out the significance of designing a arc weld-ing robot which can ensure both the precison and economy. The research and application situation have been introduced particularly, as well as robots trajectory planning, contour tracking control and the space contour error at home and abroad so that the main research contents and goals of the paper are clear and explicit.In the second charpter, the robots technical indexs have been made firstly aiming at the structure characteristic of3P3R robots. Also finished calculation, selection and test running of the servo driving system, and explained reason of smaller motor power and lower cost of this kind of robots. Based on that, the robots assembling and system integration jobs have been finished, as well as kinematics analysis which is the basis of kinetics simulation and real-time control.The third charpter mainly aims at research on robots trajectory planning both in the joint space and Cartesian coordinates. Quintic polynomial method has been adopted to plan trajectory in the joint space, which can prevent the joints from vibration and impact. Under the circumstance of fast moving, joint-space trajectory planning method with constraints of acceleration as well as velocity, has been taken into account in this paper. In consideration of the arc welding requirements, this charpter has conducted research on cartesian-space trajectory planning methods of circular arc, intersecting line and continuous line with arc connected, and deduced the intersecting line parametric equation as well. Finally3P3R arc welding robots kinetic simulation model was built up based on MATLAB/Simulink to prove all the arithmetics above with S-function.In the forth charpter, to solve the problem of none coordinate control of the3P3R robots contouring motion control system and improve the contouring tracking precisi-on, strategy of multi-axis cross coupling control was adopted. Space contour error estimation model has been established, and cross coupling controller designed. Result of the simulink simulation model indicates that the CCC strategy has played a greate role in improving the contour tracking precision.In the fifth charpter,experiments of the3P3R arc welding robots were carried out based on MATLAB/xPC real-time control system. Based on the control model set up in simulink, the robots’performance has been tested, trajectory planning and contour tracking control experiments finished.In the last chapter, a summary was made, the deficiencies and problems in the research were pointed out, the focus and direction for further research work were put forward.