Study On System Of Underwater Welding Robot Base On Vision Technology

This paper regards realizing the control strategy of “Remote Control Overall,Local Automatically” as the purpose for underwater automatic welding technology,and then researched a set of hand-eye coordination tracking control system of welding robot in underwater space.This system are composed of underwater binocular vision subsystem,robot subsystem and underwater welding subsystem.While the process of underwater welding robot tracking welding based on vision technology,which have some problems of underwater welding technology,underwater image processing,stereo matching,stereo vision 3D reconstruction,underwater camera calibration,hand-eye calibration,underwater welding robot trajectory planning and tracking control have limited underwater robot to develop.This key technology processing are more difficulty on the land,so it is necessary to do some research about this key technology of vision servo control tracking welding for underwater welding robot in this paper,its specific researching contents are as follows:(1)The surfacing welding is adopted,and the overall system hardware structure is designed through the performance of the system and characteristics of underwater welding maintenance.At the same time the relative important basic theory of the whole system is discussed in order to provide technical support for this key technology researching later.(2)A binocular vision test platform with underwater platform is developed for this topic,and the binocular vision system is rearched for underwater welding robot to using.The parts of underwater binocular stereo vision system is designed,calculated and selected in terms of hardware.The installation of mechanical structure and waterproof sealing structure is designed.In the aspect of software,the development and application of image processing procedures,with the underwater welding image noise pollution,to select the mean filter pretreatment.Aiming at the underwater camera calibration technology,a focal length compensation method is presented,this method is used as strategy of first distortion correction and after calibration,and then using the zhang calibration method to calibrate parameter of camera.At last,result of calibration is used to measure the actual space curve,to be proved correctness,feasibility and validity of the algorithm.(3)According to the actual coordinate based on camera optical center as its origin,which relative ideal coordinate deflection,and the camera's optical center can't locate,the problem of specific verification for binocular measurement results can't be caused.A coordinate system calibration method based on least square method is proposed,and detection platform is designed and developed.At last,accuracy of coordinate system calibration and binocular vision system measurement are verified and repeated stability by experiments.(4)According to be set up robot kinematics model existing shortcomings by traditional D-H method,this paper is proposed a inverse kinematics model of robot based on the screw theory,and its all sixteen of solutions is got by using Sylvester junction method.(5)For underwater welding robot as uncertainty,time-varying,coupling and highly nonlinear systems,its accurate dynamics model couldn't be set up,so active disturbance rejection control(ADRC)method based on model compensation is presented as a theoretical study.And also active disturbance rejection sliding mode control(ADRC_SMC)compound control technology is presented to improve controller dynamic and static performance,and to solve the problems existing by using a single control method.(6)Based on the needing of underwater welding for system,a kind of local dry shielding cup is designed,the structure designing is used “double loop” form for this dry shielding cup,so that it can drainage,and ensure stability ignition at the same time.At last,the designing obtained the invention patent.(7)Experimental platform hand-eye coordination control system of welding robot for underwater space is set up based on key technology researching accomplishing,and software of system is developed by combining VC++6.0 software with Open CV visual library.The system is carried out welding experiment in laboratory pool,to be simulated actual welding repair underwater of nuclear power equipment,the results of experimental show that system can realize tracking underwater weld.