Research On Visual Servo Control For Welded Seams Grinding And Polishing Robot

Because of the development of railway technique in our country and increase indemands for carrying capacity, High-speed is a tendency of locomotive development.Thus the requirements for safety and technicality of locomotive body are higher andhigher.As a kind of successful manufacture technology, weld has been widely appliedto shaping process of aluminium alloy body.While postprocessing of weld is animportant pathway to improve the body’s safety, technicality and beauty.This subject takes the National Natural Science Foundation project of China asbackground and depends on CNR Changchun railway vehicles co..To resolve theproblems of heavy labor intensity, low efficiency and low accuracy of manualgrinding, researches on Micro-polishing Robot that polishing and self-positioningwith visual servo control on free-form surface, develops a visual servo control systemfor welded seams grinding and polishing robot based on visual servo technique andimage processing technique.This system makes the robot online test and Real-timemonitor.This paper analyses the key technologies of visual servo control and uses onwelded seams processing.Refering to the robot working space and manufacturedemands, proposes the model of binocular vision together with structured light forvisual servo control system.Then researches on welded seams digital imageprocessing, integrates algorithm and calculates the oretical values of welded seams’discretization as well as coordinate transformation.Based on this model, this paper computes the parameters of hardware and selectsthem. After that, designs the structures of important parts.The joints between visualsystem and robot system are as follows: CCD fixes on robot’s chassis by flange andvibration attenuation support.Changes the position of mounting holes on flanges canmake different CCDs’ centre distances. Laser fixes on Y module slider.When Ymodule slider moves along X, the welded seams are scanned.To prove the feasibility of this model and optimize system structural parameters, designs and assembles a testbench of visual servo control for welded weams grinding and polishing robot.Software development for visual servo control system is carried out by the methodof layerings and modules.Under the environment of HALCON, programmes thebottom modules of image processing, such as module of weld image acquisition,module of weld image enhancement, module of binarization and single pixel, moduleof feature points extraction and module of3D measurement and so on.Through callingand combining the bottom modules, middle-level modules,such as one-key forcalibration, reference zero point calculation, robot navigation and auto imageprocessing,can be came true.High-rise module can automatically process the weldedseams image completely.Under VC++environment, integration of visual systeminterface and control system interface of robot makes the visual servo controlvisualization.Optimization experiments, three factors and three levels orthogonal experiments,are implemented on the test bench. According to the characters of hardwares andworking space of robot, defines CCDs’ centre distances (b), CCDs’ angle (2θ) andobject distance (z) as three factors. Analyses the error and error band of experimentalresult, and then optimizes structural parameters.