Research On Autonomous Control System Technology Of Non-silicon MEMS Flexible Micro-assembly Line

Advances in micro-assembly technology enable micro-assembly systems towardflexible, efficient mass assembly direction. Flexible modular micro assembly line came intobeing. Compared with the traditional one piece, trial type micro-assembly systems, microassembly line put forward higher requirements on assembly capacity, perception, control,timeliness and reliability of the control system. Micro-assembly technology of controlsystem becomes a key issue. This paper focuses on the realization of micro-assembly linecontrol system technology including the overall control system technology, the controlsystem hardware and software technology, precision motion control technology,microscopic study of the visual assembly technology and optimal control of stepper drivesystem control.This paper first discusses the background of micro assembly line control system andsummarizes the main related control system technologies home and abroad. For problemsabout micro-assembly line control system，presents the main research contents of this paper.(1)Research on overall autonomous control system technology of Non-silicon MEMSmicro-assembly line: Features and functional requirements of Non-silicon MEMSmicro-assembly line were analyzed. For flexible and complex systems characterized bymicro-assembly structure, Open control system architecture inclding multiple autonomousunit control module, multi-modular vision systems dedicated microscopy, multi-sensor, andeCAN bus is presented. The control system architecture regard reconfigurable control unitas the basic components when building control system. Dedicated micro-vision system isthe basic visual detection unit. CAN bus consists of reliable real-time bus communicationnetwork.Control system achieved multi-axis motion control, visual feedback control, forcefeedback control, multi-I/O logic control and other control requirements. In order to meetthe flexible requirement of micro-assembly structure, a modular and reconfigurableapproach control system was proposed. A functional analysis for software module ofcontrol system was conducted.(2)Research on unit control module of control system: In order to meet the complexneeds of micro-control assembly line control, a design method of modular, networked,reconfigurable embedded industrial control unit module was presented. Modular,networked, reconfigurable ideas were introduced into the design process, of the control unit. A hardware with the three-tier architecture of “main control module+logical extensionmodule+isolated driver modules" was implemented. Reconfigurable and high reliabledesign method was studied on the control module. Finally, a function test was performed onthe control unit. The A/D conversion accuracy and CAN bus communication performancewere verified on the control module.(3) Research on assembly precision control technology of autonomous module controlunit: Multi-axis motion control and force feedback control method were introduced. Inorder to achieve the positioning accuracy of the posture adjusting mechanism,Mathematical model of stepper motor systems and ball screw was establish throughappropriate equivalent method. The model was appropriately simplified for the purpose ofControl system design. Two degree of freedom control theory was applied to designbistable closed-loop control system of X-Y micro positioning platform. The transientresponse characteristics of the control system was Analyzed. The repeat positioningaccuracy of X-Y micro positioning system was validated by laser interferometer calibrationexperiments. In order to improve the accuracy of the feedback signal power，a de-noisingfilter method of hardware oversampling plus average smoothing method was presented. Byanalyzing the dynamics of the contact force assembled body, the a system dynamics modelof assembly force feedback mechanism was established. A PD controller which was notsensitive to identified parameters was studied through experiment using this model. Thetarget of a high damping force feedback control without overshoot was achieved by PDcontroller parameter adjustment.(4)Research on microscopic visual assembly control technology of flexiblemicro-assembly line: A designed method of precision micro-vision system dedicated toprecision visual inspection was proposed. A two modular structure micro-vision inspectionsystem including imaging subsystem, image processing subsystem was designed.Flexibility and reconfigurability of the control system were ensured. High-resolution imagecapture and display driver design and implementation underlying vision system wasconducted. The detection accuracy and detection speed of micro-vision system forassembling parts was calibrated using multi-dimensions standard gauge block with thesame material of assembly object. Through Kinematic analysis of microscopic vision, akinematic model of assembly space was established. The transfer function matrix fromassembly space to phase plane was derived. On this basis, The transfer function model ofvisual alignment system was established. Through system simulation method The looking then moving strategy, looking and moving strategy and direct visual feedback controlstrategy was analyzed. The dynamic response of visual assembly system using differentcontrol strategies was studied.(5) In order to solve the stepper motion control drive system oscillation, lost step andimbalance issues, improve control performance of stepper drive system and optimize thecontrol of stepping drive system, by studying the structure of hybrid stepper motors,stepper-driven methods and modern stepping drive system drive control process, a overallmodel of stepping drive system including speed trajectory generator, micro-step driver,hybrid stepper motor and load was established. The influence of speed trajectory control tothe performance of stepper drive system, the mechanism of oscillation, lost step anddisorders are analyzed. Steady cutoff frequency identification method and speed trajectoryoptimization control method based on stability frequency characteristics are proposed.Subsequently, an example of stepper drive systems-an arm system is tested.