Design And Research Of Wall Climbing Robot For Weld Seam Image Inspection

Inspection of pressure vessel welds is very important in the petrochemical industry.At present,most of the welds of pressure vessel inspections are manually operated.The detection efficiency is slow and working process is dangerous,especially for large and medium size pressure vessels.It is difficult to inspect welding zone defects.Considering these challenges,we propose a program to design wall-climbing robot instead of manual to perform welding image acquisition and processing.The main research contents include:(1)The overall scheme of the wall-climbing robot laboratory prototype was designed.Then the robot's magnetic attraction mode,walking mode and driving mode were analyzed and selected.A magnetic attraction unit design structure was proposed.The permanent magnet and the magnetically conductive wall surface adopt indirect contact attraction mode Through the calculation of static mechanical analysis and vertical overturning model analysis,the conditions for reliable attraction were tested.(2)The control system of the wall-climbing robot is designed,including the micro-chip computer circuit,motor drive circuit,power conversion circuit,remote communication module and image transmission module of the lower computer part;and the coding the single-chip computer control program.At the same time,based on the hardware conditions of the lower computer,an upper computer operating interface was programmed on the personal computer to perform the remote control of the robot's motion status and the function of receiving and processing video images.(3)The digital image processing algorithm is used to process and analyze the welding seam test block,to detect the location area of the welding seam and extract the information of the welding seam center line.Gray-scale and median filtering methods are implemented to smooth the images.For welding area edge detection,an improved weld edge detection algorithm is proposed.It combined the traditional Prewitt operator with Canny operator.Morphology operator is selected to extract the weld area geometry parameters for image post-processing.Finally,the Hough transform is used to obtain the weld centerline information.(4)The designed wall-climbing robot performance was tested.Firstly,the magnetic attraction effect is tested.The selected neodymium-iron-boron permanent magnet and its installation method guarantee the stable adsorption of the robot in this article.Secondly,it presents the control ability of the single-chip microcomputer and uses an oscilloscope.The output of the test single-chip computer meets the control requirements.At the same time,it is shown that the robot can be controlled remotely for corresponding movements.Finally,it proves that the upper computer control system of the wall-climbing robot owns the functions of image acquisition and processing.