Accurate Positioning Of Robot In Automatic Drilling And Riveting System Based On Photographic Measuring

Due to the advantages of high quality and efficiency,easy integration and good flexibility,robotic automatic drilling and riveting technology has become an important application and research direction in the field of aircraft assembly.At present,the positioning accuracy of industrial robots can not completely meet the requirements of aircraft drilling and riveting,which limits the development of robotic automatic drilling and riveting technology.This paper presents a method to improve the positioning accuracy of robot drilling based on photographic measuring of reference features,which takes the reference holes images by industrial camera and guides the robot to move according to the result of the images processing.The main contents and results are as follows:1.In order to calibrate the eye-in-hand system of industrial camera and robotic automatic drilling and riveting system,a calibration method based on a special calibration board is proposed.On the one hand,in this method,the tool coordinate is built relying on the board.On the other hand,by the nineholes array of the board,the camera intrinsic and extrinsic parameters can be calibrated,and the calibration board coordinate.is built to determine the hand-eye relationship.2.According to the different requirements of system calibration and visual measurement in robot drilling,two algorithm of extracting the contours and their positions of holes in the images are developed.In this paper,the algorithm of image segmentation,recognition and extraction is studied,and a subpixel edge detection based on first three gray moments is used to improve the accuracy of holes location.3.In order to improve the accuracy of position of connecting holes,this paper researched the positioning error compensation of robot in automatic drilling and riveting system.The deviation between the actual position and the nominal position of the reference holes is obtained through the industrial camera.Then the error compensation model based on bilinear interpolation is established,and the positioning error of the hole to be drilled is compensated.4.Based on the key technology and the proposed techniques,the prototype drilling positioning system based on photographic measuring of reference features was constructed,which is used to assist industrial robot to locate accurately in automatic drilling and riveting system,and the relevant software on the VS2013 platform is developed,which has the functions of hand-eye calibration,photographic measuring and error compensation etc.