| As a type of key technology in the development of modern high-tech and industry,micro/nano positioning technology has been playing a critical role in many fields such as:microelectronics manufacturing,biomedical research,precision instruments,aerospace,ultra-precision machining,communications positioning,flexible precision drive,the defense industry and so on.Among them,micro-/nano positioning stage with piezoelectric ceramic as an actuator and a variety of flexible hinges attracts a widely range of discussion by scholars all over the world.However,nowadays,existing micro-/nano positioning stages remain disadvantages of small workspace density and long positioning time,which is required to be improved urgently,but it is still challenging to design a type of high performance microstage.This thesis designs a type of microstage and the measurement&control system actuated by PZT,which is sponsored by "project of Science and Technology Foundation Project of Shenyang"(No.F13-316-1-74).The main research contents and results are as follows:(1)This thesis proposes a type of parallel microstage with high workspace density,real time response and high positioning precision based on the previous researches at home and abroad.The structure of the nano-positioning platform is designed via choosing the piezoelectric ceramics as displacement generator;designing parallelogram flexible hinges with advantages of no mechanical friction,backlash and high displacement amplification as actuator;designing parallel mechanism with decoupled X and Y DOF;choosing displacement sensors with high linerity and low volume;developing the monitoring and control system based on the DSP+FPGA control unit with rapid and high precision as well as the user interface based on USB2.0 and C++Builder.(2)Aiming at improving the work space density of the micro positioning stage,this thesis proposes a type of 2-DOF symmetrical parallel microstages.Through the analysis of the deformation magnitude of the main flexible parts in the displacement amplifier,calculation of the circular flexible hinge,parallel plate flexible hinge and corner-filleted flexible hinges were carried out.By utilizing the energy method and the displacement matrix,the output force formula of displacement amplification parallelogram mechanism and the displacement formula of the stage movement were established.By setting the output displacement of micro stage as the optimization objective,optimization function was established.Through the simulation analysis and experimental tests,the performance evaluation indexes of the optimized microstage were obtained.The theoretical calculation,simulation and experimental results show that the workspace is 143um×143um,workspace density is 2.560?m/mm2,and the relative coupled displacement is 4.2%.(3)For solving the problem of the long positioning time and the low positioning precision of microstage,this thesis adopts a type of”DSP+FPGA" based modular,high-speed and high precision microstage controller.Through the analysis of resource requirement and system function of the measurement&control system,this research conducted the program design of central processing unit based on DSP+FPGA.The user interface in the host PC was designed using C++Builder.The DSP+FPGA module was designed to communicate with the host computer through USB2.0 protocol.(4)For handling the problem that signals in the measurement&control system usually sufferes the electromagnetic interference from the noise in the internal of system and random disturbance from the external environment,this study proposed to filter the noises by adopting the weak signal adaptive threshold extraction method based on wavelet entropy theory.Simulation results and experimental results with the given threshold method were compared,and the results confirmed that after filtered with the wavelet entropy method,the signal with SNR-13.0402dB can be improved to signal with SNR 5.0988dB and SNRG 18.1390dB.(5)For handing the problem of high machining accuracy,low success rate,and the requirement of saving cost and improving effiency,this thesis conducted the virtual prototyping open-loop and closed-loop system design using co-simulation approach with characteristics of multi-platform and cross-software.Results show that open-loop system can generate proper response to all three types of input signals,but there exists an overshoot about 11.3%and steady-state error.The simulation result and experiment result of the closed-loop system show it can track the reference signal without steady-state error,but the response speed is still slow.(6)Finally,conclusion about the research is summarized.Also,this thesis puts forward some questions to study and explore in the future.Outlook of the research is presented about the key technique of the high-presion positioning stage and its measurement&control system in the coming era. |
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