Research On The Design Of Automatic Polishing Control System For Weld Defects And Trajectory Planning Strategy

Industrial robots are currently more and more widely used in production.Due to their strong adaptability and high repetitiveness,they have gradually replaced manual labor.However,it is rarely used in welding defects polishing operations,mainly because of the various types of weld defects,the location of the defects are not fixed,and the required polishing parameters depend on the characteristics of the polishing defects.Therefore,manual polishing is still used,but the efficiency of manual polishing is low.,Poor quality,high labor intensity of polishing workers,and harsh working environment.It is urgent to use robots to replace manual tasks to complete automatic polishing tasks in order to improve the production efficiency of industries such as automobile manufacturing.In order to promote the application and development of industrial robots,combined with the current needs and status quo of welding seam grinding,this paper designs a robot control system for automatic welding seam defect grinding.We mainly target two typical weld defects: weld bead and long strip weld with defects as the goal.Starting from the two existing forms and characteristics,the polishing process and the polishing trajectory are modeled separately.This article focuses on the polishing trajectory planning.The research is carried out from the issues of efficiency,stability and obstacle avoidance.The specific work is as follows:(1)Modeling of automatic polishing system for weld defectsThis article is based on the known weld defect type and location to carry out the automatic grinding design.The key of automatic polishing is mainly divided into two parts: process and trajectory.For this reason,this article has planned and modeled the two parts.Analyze the polishing process of weld bumps and long strip welds with defects,and further subdivide the two types of defects into four types by establishing a model of the removal of processed materials,and estimate the required polishing parameters for different types for process testing Parameter selection for reference.Combining the characteristics of the grinding workpiece environment and the robot's grinding movement,the grinding trajectory is divided into two parts: the tracking trajectory and the grinding path.The tracking trajectory is modeled according to the principle of obstacle avoidance,and the tracking trajectory is preliminarily interpolated.Combining with the existing form and distribution characteristics of weld defects,inspired by the Traveling Salesman Problem(TSP),construct a polished path planning model based on the shortest path principle(2)Robot polishing trajectory planningPlan the polishing trajectory with the goal of optimal time.Based on particle swarm optimization(Particle Swarm optimization),the previous trajectory planning model is used to establish the fitness functions of the tracking trajectory and the polishing path,and the constraint conditions are established for the tracking trajectory and the penalty function mechanism is introduced.Describe the trajectory,determine whether the motion parameters of the trajectory meet the constraint conditions by solving the equation,determine the penalty for its fitness function,optimize the trajectory to obtain the optimal solution;for the polished path,introduce a jump-out mechanism combination The particle swarm algorithm sorts the path points to find the time-optimal polished path.(3)Build an automatic polishing system for weld defectsIn order to achieve the purpose of automatic polishing,a robot control system for automatic polishing of weld defects is built,which mainly includes two parts:hardware and software systems.The hardware system is mainly to control the three-degree-of-freedom sliding table.Its role is to drive the camera to complete the welding seam collection work.This part of this article is mainly to design motion control without image processing.The software system mainly includes data collection management,technology Database,robot offline motion control,upper computer software interface control.The software system is mainly to realize the process and trajectory planning.According to the input of weld defect information,decision-making and planning are made,optimization results are derived,and transmission is finally carried out to control the execution of the robot.Through the host computer,the integration of trajectory planning,process parameter selection and robot control is realized,that is,data processing,data transmission,signal control,etc.are performed on external equipment to realize the task of automatic polishing of weld defects.(4)Welding seam grinding experimentThe process experiment and trajectory experiment were carried out based on the built system.The research focused on the selection of polishing process parameters,and the optimized trajectory was verified by collecting robot motion data.According to the established process model,the normal pressure of the grinding wheel and the rotation speed of the grinding wheel are changed to polish the weld bead and the long weld,and the optimal parameters are determined according to the surface roughness and the amount of material removal to improve the process database.Finally,the entire system was verified to prove the feasibility of automatic polishing.In summary and the final verification,the automatic welding seam defect grinding system designed in the thesis can better replace manual labor,solve the problem of welding bead and long weld seam with defects,and has certain reference value for the application of industrial robots.