Study On Weld Vision Characteristic For All-position Autonomous Welding Robot With Visual Sensor

The shipbuilding industry is an important part of the country's traditional industries.However,shipbuilding in China consumes a lot of energy,labor resources are scarce,and the level of automation is low.In the process of welding ship profiles,manual welding is still used.The on-site production environment is poor,the efficiency is low,and the welding quality cannot be guaranteed.At the same time,the practical needs of the welding manufacturing industry,such as the difficulty in working,the high labor cost,and the shortage of highly skilled welders,have made the “machine substitution” an inevitable trend in the transformation and upgrading of the welding manufacturing industry.In the actual welding production process,due to factors such as assembly gaps,misalignment,and uneven heat dissipation,the traditional “Teacher-Reproducing” robots are prone to problems such as deviation of welding trajectory or mismatch of welding parameters during the welding process,resulting in unstable welding joint quality,even failed.Based on the above problems,this paper develops an arc welding robot system based on laser vision sensor for the automatic welding of ship section profiles,aiming at the characteristics of ship section T-profile groove profile.With the help of laser vision sensor technology,multi-layer and multi-channel planning and welding expert system,the automatic and intelligent welding of sectional sections was successfully realized.The constructed system has the functions of initial weld identification,tracking,multi-layer planning,gun attitude,and adaptive adjustment of process parameters.Firstly,according to the requirements of welding materials and welding process used in ship T profiles,combined with the production status of shipbuilding industry,the problems faced in realizing automatic production of ship T-section counterpart welding in shipbuilding are analyzed in detail;then,the actual use of ship-based arc welding robot system is then analyzed.The environment proposes a series of performance indicators and technical requirements for the robot system.Finally,according to actual needs,the overall system design plan is proposed.The entire system consists of six parts: an arc welding robot system,a welder system,a laser vision sensor system,a welding expert library system,a multi-layer multi-path production system,and a master control system.The hardware system includes a robot system,a welding device,a line laser sensor,a main control computer,an anti-collision sensor,a gun clearer,and peripheral auxiliary equipment.The developed software system has a friendly man-machine interface and rapid response to faults,facilitating remote monitoring and operation.Secondly,with the aid of line laser vision sensor,a simple and applicable calibration method was proposed to determine the “hand-eye” relationship between the sensor and the robot.According to the two types of joints of the T-profile plate butt joint and the vertical plate butt joint,welding was proposed based on the work-piece coordinate system.First and last point seek strategy;In view of the influence of the laser incident angle,the method of extracting the center coordinate of the root of the thick plate weld was improved.The welding torch coordinate system was established on the work-piece to ensure the ideal attitude of the welding torch during welding.Seam tracking function.The welding expert system developed for segmented profiles supports the import and export of welding procedure specifications.Based on the input welding process parameters,the multi-pass multipass distribution of the weld bead is automatically planned based on the thickness of the plate,and the welding current and the weld fill are calculated using the adjacent data interpolation method.The method optimizes the welding speed and further improves the planning algorithm described above to avoid nozzle and work-piece collision problems.Finally,the ship segmented arc welding robot system developed in this paper was piloted in Dalian Shipbuilding Industry Group Co.,Ltd.ship segmentation digital workshop.A series of safe operating procedures were proposed for field applications.With the development of a welding expert system,it is possible to automatically generate welding specification parameters for work-pieces of different sizes in the field.The results of on-site welding trial production show that the use of the ship section subsection arc welding robot system developed in this paper can greatly increase the production efficiency,reduce the labor intensity of workers and guarantee the quality of welds.It is of great significance to improve the efficiency and automation of shipbuilding in China and promote the level of shipbuilding automation.