Key Measurement And Control Technology Of T-shaped Welding Robot System Based On Laser 3D Scanning

China's current ship T-section steel plate welding generally uses manual welding or automatic welding methods.These methods have long construction period,low production efficiency,and the welding quality is difficult to guarantee.In this context,based on the 3D laser scanning technology for point cloud data acquisition of ship T-section steel plate,the key measurement and control technology of T-profile welding robot system is studied.In order to achieve the design goals of the system,this paper mainly does the following work:(1)According to the application requirements of ship T-section steel plate welding,the overall scheme of the system was designed,including hardware selection and software platform design,and the specific workflow of the 3D laser scanner to collect data was developed.(2)The point cloud simplification method based on the combination of octree coding and surface feature curvature threshold is proposed to simplify the collected original point cloud data.The method divides the original point cloud data by octree coding,and obtains the feature curvature information of the point cloud region by using K-neighbor and curvature calculation.The point cloud region is divided by the curvature threshold,and is simplified by random sampling method and regional center of gravity simplification method.(3)Aiming at the noise influence and the problem of unsmoothing in the T-weld weld area,a weld seam recognition algorithm based on coordinate increment method is designed.In addition,a weld seam recognition algorithm based on eigenvalue method and distance threshold is designed.In order to verify the feasibility of the above two algorithms,the streamlined point cloud data was input into the professional reverse engineering software Geomagic Studio for surface modeling and weld seam recognition results analysis.(4)The robot kinematics model is established by D-H parameters and homogeneous coordinate transformation,and the calibration of the 3D laser scanner is completed.Based on ABB robots,3D laser scanners,PC building systems and the design of the host computer client.The real-time online planning of the weld seam identification algorithm is realized by the dual-thread concurrent execution management mechanism and the Ethernet real-time communication technology.Through experimental verification,the point cloud simplification algorithm proposed in this paper has a saving rate of 30.3% under the reduction rate of 14.7%.At the same time,the error value between the improved weld seam recognition algorithm and the weld track curve identified by Geomagic Studio,a professional reverseengineering software,is within 0.764 mm.The error value between the final program's weld track and the actual teaching weld track is within 1mm.