Research On Digital Twin Micro-assembly System For Reconfigurable Multi-manipulators Collaborative Assembly

With the development of micro precision machinery,micro inertial devices and other technologies,a large number of heterogeneous micro parts have appeared,which must be assembled into various micro mechanisms by micro assembly technology.The traditional micro-assembly system uses microscopic vision technology to assist the assembly operation,which has the problems of inconvenient observation and low efficiency.Using virtual reality technology and digital twinning technology to realize the virtualization and twinning of micro-assembly operation can reduce the requirements on operators and improve the assembly efficiency,which is the inevitable development of micro-assembly technology.At present,virtual micro-assembly system has not solved the digital twin problem of virtual and physical micro-assembly system.There are two main problems: one is reconfigurable,which can reconstruct the corresponding virtual micro-assembly system according to different assembly tasks.The second is to solve the problem of cooperative assembly between multiple operators to improve the efficiency of assembly operation.Aiming at the above problems,a digital twin micro-assembly system for reconfigurable multi-operator cooperative assembly is proposed and studied in this thesis,and the related theoretical research,system design and experimental test are completed.The main research work of this thesis is as follows:(1)In order to solve the reconfigurable problem of virtual micro-assembly system,a reconfigurable architecture of digital twin micro-assembly system was proposed,including the theoretical model and structural composition of the system.The kinematics model and mechanics model of the mechanism and components are established.The data structure and method that can manage system data are put forward.The data interaction method between virtual and real micro-assembly systems in digital twin micro-assembly system is analyzed.(2)A micro-assembly path planning method for multi-operator cooperative assembly in digital twin micro-assembly system is studied.A model level bounding box method based on OBB bounding box is proposed,which can meet the needs of path planning with different precision.On this basis,A dynamic map generation method of micro-assembly space based on raster method was proposed,and A path planning method of micro-assembly operation for three-dimensional micro-assembly space was established based on A* algorithm.(3)The micro-assembly system,data interaction interface and virtual micro-assembly system of digital twin micro-assembly system are designed.The precision and error compensation method of the designed digital twin micro-assembly system are analyzed.(4)The calibration method of the digital twin micro-assembly system was established.The calibration of the system was completed by using the micrometer calibration ruler as the reference and the visual measurement method,and the displacement error of the operator’s end was compensated.The real-time performance and the position accuracy of the open-loop control of the digital twin micro-assembly system are tested and analyzed,and the algorithm of micro-assembly path planning is verified.The experimental results show that the calibration test method is reasonable,and the trajectory of the manipulator end is optimized after the trajectory modification.Pose synchronization experiments show that the end positions of the micro clamps in the virtual space and physical space micro-assembly systems satisfy the real-time pose synchronization in the virtual and real environment.The research work in this thesis provides a theoretical basis for the research and design of digital twin micro-assembly system and has theoretical guiding significance and practical value for the development of micro-assembly technology.