Analysis Of Deformation And Error Characteristics With A Large Stroke Flexible Positioning Stage

With the rapid development of micro/-nano technology and the continuous expansion of the application,the requirements of positioning accuracy are also constantly improving in the micro/-nano precision positioning field.The traditional mechanical transmission cannot meet the actual requirements,and it is urgent to design a flexible precision positioning system with multiple-DOFs,large stroke,high resolution and dynamic characteristics.The flexible precise positioning system driven by piezoelectric actuator,and input displacement amplification and decoupling have been realized through the flexible mechanism developed by the flexure hinges.The movement of multi-DOF is finished by different combinations.It has many advantages such as fast response,high control accuracy,small volume and mass,and it has good development and application value.It is a research hotpot of precise positioning system at home and abroad.Therefore,it is of great significance to carry out the research of flexible positioning system with large stroke and high precision for promoting the development of relevant technologies in the field of flexible micro/-nano positioning in our country.This paper based on the Open Foundation of the Shanghai Key Laboratory of Space Vechicle.The working principle,structural design,coupling errors,attenuation errors,experimental measurement and the optimization design of flexible precise positioning system are carried out.The main research contents of this paper are summarized as follows:(1)The working principle and components of the flexible precise positioning system with multi-DOF and large stroke are studied.The working principle and components of the flexible precise positioning system are analyzed by using the theory of compliant mechanism and the elastic beam.The deformation principles and characteristics of driving elements,flexure hinges and compliant mechanisms are discussed,and the selections and characteristics of different elements are determined in the positioning stage.(2)The error characteristics and output amplified characteristics of the flexible precise positioning system with multiple-DOF and large stroke are studied.Based on the pseudo-rigid body model method,elastic beam theory,virtual work principle,energy conservation and other theories,the coupling error caused by the flexible precise positioning platform’s gravity is modeled and analyzed,and the influence of external load and self-weight on the gravity coupling error is discussed.The input / output stiffness model of the flexible precise positioning platform is established,considering the effect of structural stiffness on the actual output displacement of the positioning platform.The error attenuation model of the flexible precision positioning platform is established.The relationship between the output deformation and the attenuation error has been analyzed through the "attenuation factor".Based on the theoretical derivation model,the actual output model of the flexible positioning stage is established,and the output errors and the amplified characteristics of the positioning stage are obtained.(3)The error measurement and analysis evaluation of the multi-DOF and large stroke flexible precision positioning system are studied.A six-DOF precision positioning stage with error measurement system is built,and the single-axis motion error,multi-axis motion error and gravity coupling error of the positioning stage are performed.The theoretical model of the flexible precision positioning stage is verified by the results of the FEA.And the output error characteristics of the positioning stage are evaluated and analyzed.(4)The optimistic design and static/dynamic characteristics of the multi-DOF and long stroke flexible precise positioning system are studied.Based on the attenuation error and gravity coupling error models of the flexible precise positioning platform,a new flexible precise positioning stage with the large stroke and two-DOFs is proposed.The input displacement is amplified and the dynamic characteristics are improved by the hybrid multi-stage displacement amplification mechanism The static and dynamic model of precision positioning stage is established,and it meet the requirements of working stroke and dynamic characteristics compared with the FEA results.