Design Of Micro-operation Stage With Variable Stiffness Characteristics

Micro-operation stage is widely used in the fields of bioengineering,micro-mechanical manufacturing,aerospace and other fields.With the development of science and technology,new performance requirements for micro-operation stage are put forward.In some application areas,the stage is required to have multi-stroke,multi-rate performance.In order to meet the requirements of multi stroke and multi resolution stage,three design ideas of variable stiffness stage are proposed in this paper.The main contents are as follows:In order to meet the requirements of compact,large motion range,high natural frequency,decoupling motion and high motion accuracy of micro-operation stage,a novel 2-DOF microoperation stage is presented.The leverage flexure mechanism is designed to displacement amplifier.The double parallel four-bar flexure mechanism is used to guide.The mechanical model reflecting static stiffness,displacement magnification and natural frequency of the stage is established by using pseudo rigid body method and virtual work principle.The prototype of the stage is manufactured.And the experimental system is built to test the performance of the stage.Experimental results showed that the displacement amplification rate is up to 4.5,the stiffness is 5.79 N/?m and the natural frequency is 580 Hz.The index reflecting the coupling degree of the stage along the x and y directions are 1.3 ‰ and 1.2 ‰,respectively.The repeat positioning accuracy along x and y are 0.68 ?m and 0.72 ?m.Therefore,the presented stage can achieve the design goal.Aiming at the integration problem of displacement sensing in micro-operation stage,a resistance strain gauge integrated with micro-operation stage structure is put forward to realize structural sensor integrated design.The optimum target is the maximum strain of the driving direction strain sensor unit and the minimum strain in the coupling direction strain unit.The relationship between the output displacement of the micro-operating stage and the strain of the displacement sensor unit by the least square method The fitting results show that the strain relation between the output displacement and strain unit of the micro-operation stage is firstorder polynomial,and the proposed design idea provides a novel thought for the integrated displacement design of the micro-operation stage.To design a multi-resolution and multi-stroke micro-operation stage,a design idea of series variable stiffness stage is proposed.The micro-operation stage is composed of a rigid component and a flexible component interacting with each other.When the stage moves for a stroke,the rigid members are in contact with each other,so that the flexible members connected to the two rigid members lose their functions,the flexible members in series are reduced,and the stiffness of the stage increases,which achieves the effect of variable stiffness.Based on this idea,the stiffness of the flexible member on the multi-stage variable stiffness stage and the gap condition between the rigid members are deduced under normal circumstances,and the design principle of the multi-stage series variable stiffness stage is obtained.According to the principle of variable stiffness,a two-stage variable stiffness and three-stage variable stiffness microoperation stage was designed to produce prototypes for experimental verification and analysis.The experimental results show that the designed stage is in conformity with the principle of variable stiffnessTo design a multi-resolution and multi-stroke micro-operation stage,two design idea of parallel variable stiffness is proposed.The design idea of the stage is that when the microoperation stage moves a stroke,the rigid components are in contact with each other,so that the flexible members connected to rigid components work at the same time,the parallel flexible components increase,and the stiffness of the stage increases,which achieves the effect of variable stiffness.Based on this idea,the relationship between the rigidity of the parallel multistage variable stiffness micro-operation stage and the stiffness of the flexible members and the relationship between the strokes and clearances at various stages of the micro-operation stage are deduced and a parallel multi-stage is derived.The design principle of the variable stiffness stage provides a theoretical basis for designing a multi-stage variable stiffness micro-operation stage.According to the principle of variable stiffness,an experimental verification and analysis of machining prototype.The experimental results show that the designed stage is in conformity with the principle of variable stiffnessIn order to meet the design requirements of variable stiffness,large travel and motion decoupling of multi-dimensional micro-operation stage,a new two-dimensional variable stiffness micro-operation stage is designed based on the longitudinal parallel variable stiffness design principle.,The prototype of the machining stage is tested on the stiffness and decoupling properties of the micro-operation stage.The experimental results show that the two-dimensional stage can achieve the design requirement of variable stiffness and has good decoupling performance.