Research On Communication And Control Techniques Of Industrial Visual Robot

With the raid development of computer science, digital image processing, pattern recognition technology and theory, the robot with visual system occupies an increasingly important proportion in the robot family. Compared to the traditional robot, the robot with visual system can have independent access to external image information, to perceive the surrounding environment changes, so it has the high movement precision, strong adaptability, strong anti-jamming capability, and many other advantages.As a typical industrial robot, horizontal 4-axis SCARA robot can make the visual guiding function by equipping it with visual system. In order to achieve its motion control, the open robot control system structure based on PC and motion control card has been adopted by author in this thesis. The key research object in this thesis is the robot control software in PC. The core contents of this paper are as follows:1) Robot language and interpreter: the “topic type” robot language order set has been designed in this thesis. Through a combination of its internal contained order, the robot control software users can quickly, conveniently complete the writing work of source control program. In order to convert the source control program, written by the user, to the actual robot control order, the robot language interpreter based on the Lua scripting language has been designed. It uses the 2 layer scanning structure. At the same time, each subroutine’s design method involved in the execution process of the interpreter has been discussed in this thesis.2) Robot visual guide: the proprietary robot visual guidance subsystem, which is used for processing image information collected by digital camera and getting the target object position information in the robot coordinate system, has been designed and implemented in this thesis. After the analysis of the practical robot applications scenarios, the method of image processing and template matching based on Median filter, Otsu, Canny edge detection, Contour moment invariants has been determined. After the analysis of the pin-hole camera model, the camera parameters model, the distortion model of the camera lens and the hand-eye relationship, the camera internal and external parameters calibration mode based on Zhengyou Zhang camera calibration method has been adoped. Besides, the hand-eye relationship calibration mode based on the least square method has been used.3) Robot data communication: after passing the test, in order to enhance the real-time properties of the robot control system in the future, the Ethercat real-time Ethernet technology has been studied in this thesis. After the analysis of EtherCAT master framework under Linux and the working mechanism of the master core state machine under this framework, the control software communication interface based on EtherCAT master and sending-receiving data frame format based on this interface have been designed in this thesis.After repeated testing, debugging, the horizontal 4-axis SCARA industrial robot control system with the visual system, which has been studied and designed in this thesis, is able to complete the visual guide job. And it can be applied to goods handing work, parts assembly work, parts online testing work and many other different applications scenarios. Besides the positioning accuracy of this industrial robot control system can reach 0.05 mm. In the related software design part of this industrial robot control system, the robot language interpreter based on Lua scripting language has been implemented. This method has not been reported in China.