Abstract: To solve the problem of stiffness matching of constant-force micro-motion stage,a design idea of forming constant-force stage was proposed by using the positive and negative stiffness structure with linear mechanical relations.To form a zero-stiffness structure,two kinds of Z-style and trapezoid positive-stiffness structure were designed respectively,which the force-displacement relations were lniear.Combining the proposed two kinds positive-stiffness structures and the bistable-beam structure with linear negative stiffness,two novel constant-force micro-motion stages were proposed.The mechanical model of stages was established with pseudo-rigid-body method.Based on this model,the linear positive and negative stiffness matching principle was used to determine the structural parameters of the stages.The prototypes were made and the comparative analysis with the stage of nonlinear mechanical relationship was carried out.The theoretical and experimental results showed that the constant-forec range of the proposed stage could reach 2.4 mm,and the range of stage made up of a nonlinear structure increase by 1.3 mm.Thus,the feasibility of the constant-force stages design was illustrated.The proposed method provided a more simple design idea for the design of constant-force micro-motion stage.

Key words: postive and negative stiffness matching, compliant mechanisms, constant-force micro-motion stage, negative stiffness, zero stiffness

摘要： 为解决常力微动平台的正负刚度匹配问题,提出一种利用具有线性力学关系的正负刚度结构形成常力平台的设计思路。为了形成零刚度结构,分别设计了Z字型和梯形两种力—位移关系为线性的正刚度结构。将所设计的两种正刚度结构与具有线性负刚度力学特性的双稳态梁结构进行组合,设计了两种新型的常力微动平台。采用伪刚体方法建立了平台的力学模型,基于该模型采用正负刚度匹配原理确定平台的结构参数。制作样机并与具有非线性力学关系的正刚度结构平台进行比较分析,理论和实验结果表明所设计的平台的常力范围可达2.4 mm,比非线性结构组成的平台增大了1.3 mm,说明了常力平台设计的可行性。所提方法为常力微动平台设计提供了一种更为简易的设计思路。

关键词: 正负刚度匹配, 柔顺机构, 常力微动平台, 负刚度, 零刚度