Design And Key Technology Research Of Large Scale Submicroradial Rotary Positioning Platform

For space-based high-performance precision transmission components,the need for miniaturization and functional integration of their structures is increasing,which requires more compact components and more complex micro-devices and systems.The traditional transmission method can not meet its needs.The piezoelectric ceramic-driven transmission positioning system has the advantages of high power density and functional integration,high dynamic response,high resolution,large driving force,etc.Currently,research on nano-scale precision transmission and drive has been widely applied.However,for a piezoelectric drive-based nanopositioning system,its maximum transmission displacement can only reach one thousandth of its own size,and usually only achieve the micrometer/milliradial range of motion.This makes it difficult for traditional nanopositioning technology to achieve large-scale rotary precision transmission and operation in a limited space.In view of the above problems,this thesis is based on the piezoelectric ceramic drive,and the design of the compliant variable displacement amplifying mechanism and the rotary compliant micro-transmission mechanism,combined with the stick-slip drive principle,introduces a combination of feedforward and feedback controllers.A series of studies have been carried out to realize the large-scale submicroradial precision positioning platform.Firstly,based on the characteristics of the compliant transmission mechanism,this paper has carried out in-depth research on the design criteria of the compliant transmission,the design of the compliant mechanism,the analysis method of the stiffness characteristics of the compliant mechanism,and the analysis of the accuracy characteristics of the compliant structure,and comprehensively grasped the compliant transmission mechanism.Through the stiffness analysis,the design criteria and optimized design flow of the precision compliant guided micro-drive positioning device are studied.The specific research is as follows: This paper presents the design of a novel flexure–based vertical(or Z–axis)nanopositioning stage driven by a piezoelectric actuator(PZT),which is capable of executing large travel range.The proposed stage consists mainly of a hybrid displacement amplification mechanism(DAM),a motion guiding mechanism,and a decoupling mechanism.The hybrid DAM with amplification ratio of 12.1 is developed to transfer the transverse motion of the PZT actuator into the vertical motion.The motion guiding mechanism is introduced to avoid cross coupling at the output end.The decoupling mechanism can significantly reduce the cross coupling at the driving end to protect the PZT.The stiffness and dynamics of the proposed stage are improved by these mechanisms.Analytical modeling and finite element analysis(FEA)are then adopted to optimize dimensions of the stage.Finally,a prototype of the stage is fabricated and tested for verification.The results of static and dynamic tests show that the proposed stage is capable of vertical travel range of 214 ?m with resolution of 8 nm,and the first two resonance frequencies are 205 Hz and 1206 Hz,respectively.Cross coupling tests under various lateral loads(0 g–1000 g)show that the maximum variances of the lateral and angular cross couplings are less than 0.78 ?m and 95 ?rad,respectively,indicating good decoupling capability.In addition,the low–profile structure of the stage is well suited to be used in limited vertical space.Aiming at the requirement of sub-micro-radial rotary precision positioning,a precision compliant rotary micro-transmission mechanism based on PZT driven was designed.The phased research results of compliant drive characteristics analysis and comprehensive design were summarized.On the basis of theoretical analysis and research,the structural design of the mechanism,the establishment of analysis models of kinematics,statics and dynamics,finite element analysis,and the development of prototypes were completed.The displacement,bandwidth and rotation accuracy of the experiment were studied experimentally.The transmission mechanism ensures that the maximum rotational displacement is 1.64 mrad,the maximum drift of the center of rotation is less than 0.3 ?m,the natural frequency is 423 Hz,and the closed-loop rotation resolution is better than 0.2 ?rad,which verifies the effectiveness of the configuration design and analysis method.The performance requirements and prototype realization of the transmission characteristics of the single-piezoelectric precision slewing mechanism are completed.The innovative driving method and the design of the compliant mechanism are one of the innovations of this paper.The precision micro-drive positioning device can realize angular motion with sub-microarc metric resolution and high dynamic characteristics.The research on the design and characteristic analysis method of ultra-precision and compliant drive mechanism is an important key technology for the research of this paper.Combining the piezoelectric drive and the stick-slip drive mechanism to realize the large-scale precision positioning technology as the research object,a new large-scale submicro-radius-level rotary positioning platform is designed.The platform can achieve 360° unrestricted rotational positioning while ensuring sub-micro-radiation level positioning accuracy.And a micro-clamp rotary slider with adjustable friction is innovatively proposed,which can actively adjust the friction according to the change of load.The combination of innovative driving methods is one of the innovations of this paper.These aspects of research have important theoretical and practical value for improving the performance and practicability of large-scale submicro-radial-level rotating positioning platform and promoting the development of nano-positioning and nano-operation technology.At the same time,in order to meet the needs of stick-slip drive,the phase lag and oscillation of the periodic sawtooth wave are tracked by the piezoelectric precision microtransmission mechanism.The Bouc-Wen hysteresis model is selected and the nonlinear and linear system identification is obtained by genetic algorithm.The model parameters,combined with the improved zero-phase-difference feedforward compensation controller and the high-bandwidth feedback controller,enable the system to quickly track the input signal and reduce the oscillation of the system,ensuring large-scale submicroradians.The reliability of the prototype of the rotary positioning platform is verified.