Research On Obstacle Avoidance Path Planning And Trajectory Optimization For Welding Robots

In view of the low productivity,poor processing environment,and unstable welding quality of manual welding,and the advantages of welding robots with high independent movement capability and movement accuracy,which are not restricted by working time and workplace,welding robots are used instead of hands for welding processing tasks to achieve automation of welding production.In order to achieve the goal of autonomous obstacle avoidance and efficient and smooth operation of welding robots,this thesis takes the six-degree-of-freedom welding robot IRB4600 as the research object.Kinematic analysis,obstacle avoidance path planning,trajectory optimization,and virtual simulation studies are conducted for this robot,the main contents are as follows:Firstly,based on the improved D-H method,the IRB4600 linkage coordinate system of the welding robot is established for positive kinematic analysis,and the inverse kinematic solution is carried out by the analytical method.A simulation model is established in MATLAB software for positive and inverse kinematics simulation verification and workspace solution to provide the theoretical basis for subsequent path planning and trajectory planning.Next,the obstacle avoidance path planning is carried out.The obstacles are simplified as spherical envelopes,and the connecting rods of the robot arm are simplified as cylindrical envelopes,and the safety distance is set as the constraint in the working space based on the collision detection principle;the shortest path and the smallest total deflection angle are taken as the optimization objectives,and the sixth polynomial with six terms as adjustable coefficients K is introduced for obstacle avoidance path planning in the joint space.To address the problem of poor local convergence of the Sparrow Search Algorithm,the initial population is optimized by using the Cauchy Reverse learning,and the perturbation mechanism of the Firefly Disturbance is introduced to enhance the local merit-seeking ability of the optimization algorithm.MATLAB simulation results show that the Improved Sparrow Search Algorithm successfully achieves obstacle avoidance path planning and all performance indexes are better than the traditional Sparrow Search Algorithm,and the Improved Sparrow Search Algorithm has faster search speed.Subsequently,joint space trajectory optimization is performed.To improve the operating efficiency of the welding robot and reduce the impact of motion shocks on each joint,trajectory optimization is carried out by using the motion parameters of each joint of the robotic arm as constraints and time and shock as performance indicators.By introducing weight coefficients to construct an objective function,the multi-objective optimization problem is transformed into a single objective optimization problem.The Improved Sparrow Search Algorithm is used to optimize the time and shock in the joint space,and the optimized motion trajectory is obtained by using Quintic B-spline curve.From the MATLAB simulation results,it can be seen that the optimized welding robot operation efficiency is improved by 30.28% and the impact of motion shock on each joint is controlled within the safe range,which improves the work efficiency and ensures the stable operation of the equipment at the same time.Finally,the IRB4600 simulation experiment platform is built in the ROS simulation system to simulate and verify the path planning and trajectory optimization results.The simulation results show that the path planned by the improved algorithm can successfully achieve obstacle avoidance;by monitoring the motion parameters of each joint of the robot arm after trajectory optimization,the motion curve consistent with the MATLAB simulation results can be obtained,which verifies the effectiveness of the trajectory optimization method.