An Omni-directional Mobile Welding Robot With Manipulator Arm Motion Planning And Control System Design

The shipbuilding industry is an important pillar of China’s industrial production,and welding robotics can improve industrial efficiency and reduce production costs.In view of the existence of a large number of linear welds and right angle welds in lattice steel components of ships,and the limitations of traditional fixed welding robots in lattice welding,this paper adopts a mobile welding robot with an all-round mobile platform and a four-degree-of-freedom robot arm as the actuator as the research object.The robot has a wide working range and works dexterously,and is suitable for working on large welding parts,thus improving the level of ship welding automation.Firstly,in this paper,we take an all-round mobile welding robot as the research object,and model and analyze the positive and negative solutions of the mobile platform respectively;we analyze the kinematic modeling of the robot arm part through the D-H parameter method,derive the positive and negative kinematic solutions,and build a Simulink 3D model of the robot using MATLAB to verify the correctness of the kinematics;we also establish the overall kinematics of the mobile welding robot to provide a theoretical basis for the trajectory planning of the welding robot in the later paper.Secondly,the kinetic equations are established using Lagrangian mechanics and the kinetic and potential energies of the joints of the welding robot are derived,and then the kinetic equations of the entire welding robot are analysed and validated using ADAMS kinetic simulations of the welding robot to study the relationship between moment,velocity and time during robot motion and to verify the mechanical performance of the mobile welding robot in this paper and the smoothness of the mechanism’s operation.Thirdly,the robot’s trajectory planning is then studied,with polynomial interpolation algorithms and S-shaped acceleration/deceleration algorithms in joint space,and linear planning algorithms and circular arc planning algorithms in Cartesian space,respectively.Two different welding trajectories were planned when the actual welding object was a right-angle weld.The continuous variation function of each joint angle is obtained by inverse solution,and the crossover and variation probabilities of the genetic algorithm are improved to optimise the working time of the whole robot arm and improve the efficiency of the robot.Finally,the hardware of the mobile welding robot is selected according to the actual requirements,the hardware control system of the welding robot is built,the hardware circuit is improved and optimised,the upper computer control interface is designed,the control system is debugged and the welding experiments are completed with straight and right angle welds to verify the feasibility of the mobile welding robot for lattice type welds.