Research On Piezoelectric Spatial Pointing Mechanism Based On Flexure Hinge

At present,the pointing mechanism of laser communication terminal researched by many countries has many problems,such as large volume,mass and energy consumption,which can not adapt to the development trend of miniaturization and lightweight of laser communication terminal.The flexible mechanism driven by piezoelectric ceramic stack has become a research hotspot in the field of high precision because of its high precision,compact structure and low energy consumption.Therefore,the research of high precision,compact,lightweight and piezoelectric spatial pointing mechanism is of great significance to promote the development of micro and small pointing mechanism in the field of laser communication in China.In this paper,a piezoelectric spatial pointing fine tuning mechanism is designed for the performance objectives of single degree of freedom,large displacement stroke,power failure holding,compact lightweight and high resolution displacement output.First,the mechanical properties of the flexible hinge are studied.Based on the theory of elastic mechanics,the flexible hinge is assumed to be a cantilever beam with variable cross-section.The general mathematical analytical formulas of the displacement and rotation angle,stiffness,maximum elastic deformation and motion accuracy characteristics of the flexible hinge with different sizes and different shapes are derived using the load superposition method and the stepwise deformation effect superposition method.Combined with Workbench simulation software,the uniqueness of the rigidity of the flexible hinge is simulated and verified.The maximum error is 4.85%,which proves the correctness of the theoretical model of the mechanical characteristics of the flexible hinge.The influencing factors of mechanical characteristics are explored,and the relationship between the characteristics of flexible hinges and various factors is analyzed.Then,the structural design of fine adjustment mechanism is studied.Combining the requirements of the subject index and the principles of mechanism design,a compact and lightweight mechanism design method is proposed.The working principle of the fine-tuning mechanism is explored.The whole mechanism type is determined,and the degrees of freedom and magnification of the mechanism are analyzed.The rod model is used to statically model the braking mechanism.The optimization goals,influencing factors and evaluation indexes of the braking mechanism and the driving mechanism are determined according to the subject index.The optimal design is combined with Matlab to obtain the optimal size of the braking mechanism and with orthogonal test method to obtain the optimal size of the driving mechanism.Combined with Workbench simulation software,the static and dynamic analysis of the braking mechanism and the driving mechanism are carried out to determine the rationality of the structure size design of the fine adjustment mechanism.Finally,the key indicators and performance of the fine-tuning mechanism are analyzed and verified.Based on the piezoelectric-static coupling analysis theory,a finite element simulation model of the piezoelectric stack drive source is established.By analyzing the mechanical characteristics of the drive source,the preloading problem of the piezoelectric ceramic stack is studied and its preload is determined.The compact and lightweight mechanism is evaluated,and the space ratio is calculated to be 4.48.Combined with the simulation software,the displacement stroke of the mechanism under load and no-load conditions is verified to be 35.9?m and the resolution is 0.023?m.Through the contact analysis,the braking reliability of the mechanism is verified.Through the piezoelectric-structure coupling analysis,the reliability of the braking of the piezoelectric stack of the braking mechanism when the input voltage is 127.16 V is verified.The maximum driving force and output displacement of the intermittent working mode and scanning working mode of the mechanism can meet the driving performance requirements.It reveals the reliability of fine tuning mechanism performance.