Research On Motion Control System Of Submarine Pipeline Maintenance Welding Robot

Submarine pipeline transportation is the main way of offshore oil and gas production and transportation.With the deepening of deep-sea oil and gas development,the increase of the length,depth and service time of submarine pipeline laying,and the increase of potential maintenance workload of submarine pipeline,major foreign oil and gas companies continue to research and develop underwater pipeline maintenance technology.The research on repairing technology of deep-water submarine pipelines and important structures has been gradually carried out in China,and the prototype of submersible deep-water pipeline repairing project has been preliminarily completed.According to the technological characteristics of submarine pipeline maintenance,the structure of submarine pipeline maintenance and welding system is analyzed.By studying the key technology of motion control system of submarine pipeline maintenance and welding robot,we can realize the trajectory planning and adjustment of multi-pass fillet weld and the motion stability control of rotary mechanism.The main research work of this paper is as follows:1.According to the requirement of dry high pressure maintenance welding technology for submarine pipeline and the structure of each functional unit of maintenance robot,the functional control scheme of each axis of motion control system for submarine pipeline maintenance welding robot is put forward,and the key technology of the research is clarified.2.The structure of motion control system for submarine pipeline maintenance welding robot is studied.By adopting A multi-axis motion control scheme,a hardware system of motion control system for submarine pipeline maintenance and welding robot is established.Andthe functional subsystems of submarine pipeline maintenance and welding robot is designed.Therefore,the distribution control system of multi-axis motion based on EtherCAT,Device NET welding power supply control,angle sensing speed control and integration are formed.The designed motion control system provides hardware basis for welding speed smoothness control,torch attitude control and multi-layer,multi-pass trajectory planning control.3.Aiming at the technological characteristics of submersible submarine pipeline maintenance welding robot for fillet weld multi-layer and multi-pass welding,this paper analyzed the adjustment scheme of welding torch posture of maintenance welding robot.On the premise of equal cross section of each fillet during multi-layer and multi-pass welding,a strategy of fillet weld multi-layer and multi-pass welding bead layout was put forward,The trajectory planning of multi-layer and multi-pass welding for sleeve fillet weld is realized by changing the moving coordinates of welding torch and the relative position coordinates of welding bead.The welding torch swing strategy and dry elongation adjustment strategy of fillet weld placement were designed.4.Aiming at the accuracy and stability of welding speed control in all-position welding with variable load operation in deep water environment pipeline maintenance,a double closed-loop variable gain control algorithm based on inclination sensor and incremental coding is proposed.The test results show that the control strategy guarantees the motion control accuracy of rotary motor and the smooth operation of the whole maintenance process.5.The principle of EtherCAT equipment model and the data exchange process of servo driver slave station unit are studied.The master-slave communication based on EtherCAT is completed.The software of motion control system for submarine pipeline maintenance and welding robot is designed and compiled.The software system mainly includes motion control program and human-machine interface program.The submarine pipeline maintenance and welding is realized by programming.The functions of motion control,welding parameter management and fault real-time processing of the motion control systemof the receiving robot are introduced,and the motion trajectory of the welding torch is simulated by 3D data tracking function.The above research results provide a basis for the manufacture of submersible submarine pipeline maintenance and welding robot system engineering prototype,lay a foundation for further research on Key Technologies of intelligent pipeline maintenance system,and will effectively promote the practical engineering application process of submersible submarine pipeline maintenance and welding equipment.