Research On Path Planning For Ultrasonic Scanning Based On Laser Scanned Data

Arc welding technology is widely used in modern manufacturing industry,and the quality inspection of weld after welding plays an important role.At present,weld quality inspection is mainly carried out by manual method,and it is easy to be affected by subjective factors,leading to false detection or missed detection and low efficiency.This problem can be solved by automatic welding seam detection technology which combines modern robot technology with visual sensing technology.In order to realize the automatic detection of welding seams,a three-dimensional welded seam measurement system composed of a six-DOF joint robot and a three-dimensional laser scanning probe is established in this paper,and a method of identifying the boundary points of the welded seam based on line scanned data is proposed and implemented.The ultrasonic scanning path is planned based on the identified boundary points,so as to realize the ultrasonic automatic detection of the welded seam.The main research contents of this thesis are as follows:(1)The synchronous data acquisition of the robot encoders and the laser scanning probe is implemented.The three-dimensional scanned data of the welded seam in the local coordinate system is transformed into the global coordinate system of the robot with the D-H model.(2)An algorithm was proposed and implemented to extract the boundary points of the welded seam for the scanned data.The bump of the welded seam on the workpiece is not obvious,and the data is noisy.No exisitng algorithm can be used.In this paper,the discrete curvature of the scanned line data is accumulated and analysed,and an algorithm for extracting the boundary points of the welded seam is proposed and implemented.(3)The path planning of roboticultrasonic scanning is implemented.Based on the three-dimensional scanned data of the welded seam and the extraction result of the boundary,the path planning of robotic ultrasonic scanning is implemented,and the path is transformed into a language that is executable by the robot,and then the file is input into the robot controller.At last,the ultrasonic detection probe is driven by the robot to realize ultrasonic detection of weld defects.