Research On Free-form Surface Seam Tracking Method Based On Multipole Array Capacitance Sensor

Free-form surface is widely used in the structural design of modern industrial products because of its beautiful shape and outstanding mechanical properties,however,free-form surface parts with complex surface shape also bring great difficulties and challenges to automatic welding,the difficulty lies not only in the tracking and rectification of welds,on the other hand,the difficulty of surface identification is more prominent.At present,the welding automation of free-form surface weld is still low,it still depends on manual welding,there is a lack of equipment and methods that can effectively improve the degree of free-form surface welding automation.In this paper,according to the characteristics of free-form surface weld,a new multipole array capacitance sensor for free weld identification is designed,the design theory and the method of surface reconstruction are studied,proposing a free-form surface seam tracking method based on multipole array capacitance sensor,It effectively solves the key problem of low accuracy of free-form surface weld identification,the specific research contents are as follows:1)A multipole array capacitance sensor is designed to satisfy the sampling ability and accuracy of free-form surface weld.According to the working principle of capacitance sensor,the design basis of the multipole array capacitance sensor is determined.The movement mode of sensor probe is analyzed,using MATLAB to simulate the motion track of the sensor probe,the rationality of the sensor design is verified.2)A complete seam tracking system is designed,the system composition,operation process and important design links are described.The whole structure of the automatic welding system is designed with the multipole array capacitance sensor as the core,according to the inverse kinematics of the robot,a mathematical model is established to solve the coordinate position of the sensor sampling point,using LABVIEW and combining data acquisition card and motion control card,the tracking recognition and automatic welding of the seam tracking system are realized.3)A surface reconstruction method based on PSO-Loop subdivision algorithm is proposed,the shape of free-form surface weld was reconstructed.According to the sampling method of the multipole array capacitance sensor,the spatial distribution of sampling data points is determined.First,using the two-dimensional Delaunay triangulation algorithm to determine the initial triangular mesh,the efficiency andaccuracy of PSO-Loop subdivision algorithm is verified by algorithm simulation,it effectively reduces the complexity of normal vector solution,the shape of free-form surface weld is reconstructed.4)The welding effect of this method is verified by the welding test of free-form surface weld.According to the proposed free-form surface seam tracking method based on multipole array capacitance sensor,the welding seam tracking test platform is built,the results show that the method described in this paper has high accuracy and good welding quality.