Design Of Motion Control System For Assembly Line Of Visual Positioning Robot

With the prevalence of intelligent robots with the functionality of visual recognition in the intelligent manufacturing industry,it gradually becomes a mainstream to compose a novel assembly line with intelligent robots,while the previous one only depends on manual efforts and specialized machines for industry.As the core technology for the precise assembly and efficient production,motion control systems have been drawing wide research.However,most of the existing motion control systems in China are centralized and specialized,leading to the limitations in promotion and secondary development.As a result,these existing motion control systems do not meet the requirements of modern intelligent and precise assembly.The research work of this thesis was supported by the Key Laboratory of Robot and Intelligent Technology.Aiming at the precise assembly of small parts,the experimental platform of the assembly line with visual positioning robots was built.Specifically,this study focuses on the design of an open,intelligent and scalable assembly line motion control system to simultaneously meet the demands of accurate control and practical applications,and also meet the requirements of openness and scalability of the system in scientific research and teaching.The research in this thesis can be summarized as follows:(1)Developing an experimental platform for the assembly line,of which the core component is the visual positioning robot.By analyzing the assembly process for small parts,the structure and functionalities of the proposed motion control system were determined accordingly.Also,this work completed the division of functional modules and the selection of main components such as motion controllers,control motors,robots,driving elements,actuators,sensors and conveyors.Then the overall design of the motion control system was given.(2)According to the requirements of the modern precise and intelligent assembly process,the visual positioning system was introduced into the motion control system.The position and orientation of the target workpieces and assembly points like the center coordinates,angles and discrete points of the contour edge,were obtained from the captured images.Then,based on the analysis of the main structure of different types of robots and the movement characteristics of the end actuator,the establishment of kinematics equation and the inverse solution of the joint expression were completed.Besides,the optimal solution was determined.Finally,the Akima algorithm and 4-3-4 interpolation method were used to complete the trajectory planning of main station robots.It provided the theoretical foundation for the software design of the upper computer system.(3)Based on the characteristics of DVP60-15MC main motion controller,the motion position control mode of the servo drive module was designed.The precise control of 11 groups of servo motors was realized through CANopen communication.According to the control requirements of each functional module and the hardware characteristics of the peripheral equipment,the I/O address of the main motion controller was assigned.Furthermore,the electrical systems including main circuit,servo drive circuit and drive module circuit and the pneumatic driving module were designed.Finally,the motion control cabinet was designed and installed to complete the general assembly of the hardware system.(4)By analyzing the requirements of software design,the structure and implementation method of the software system were determined.Inspired by the idea of modularization,software programming was divided into two parts:controller programming and upper computer software development.Based on the kinematic analysis of robot and the research of the trajectory planning algoritfun guided by vision,the upper computer software sent the processed data instructions to the lower computer through network communication.After decoding process with the controller according to the customized communication protocol,the lower computer invoked the motion instruction block to respond to the control request of the upper computer to complete the data exchange and instruction exchange of the system.Finally,a user-friendly human-computer interface was made to realize manual single-step debugging,automatic operation and online monitoring and alarm of operation status.The experimental results demonstrated that the designed motion control system is reliable,flexible,intelligent and expandable,compared with the previous work.Specifically,the designed system can efficiently control the assembly line of visual positioning robot with high precision so as to achieve the process operations of gluing and sealing,precise assembly and locking screw for the target workpiece,which is of great significance to both the industrial production of precise assembly and the scientific research and teaching.