二级杠杆式微牛级微力发生机构

Design and functional analysis of a micro-Newton force generator

针对力传感器标定系统难以精确加载微牛级微力的现状,设计了一种二级杠杆式微力发生机构。首先,在比较了常用柔性铰链精度性能的基础上,介绍了微力发生机构的工作原理。然后,在考虑杆件变形和柔性铰链中心偏转的基础上,分析了各级杠杆和各柔性铰链的受力和能量传递情况,推导了二级杠杆式微力发生机构力缩小倍数的理论计算方法,并以实现某一力缩小倍数为设计目标,据此提出了微力发生机构的优化设计方法。接着,进行有限元仿真分析,得到了不同输入力下的力值响应特性。最后搭建了微力发生机构的性能实验测试平台。结果表明,有限元分析、实验结果与理论力值间的最大误差分别为5.501%和7.391%,实验非线性误差为2.89%,可实现0～500μN的微力加载。认为力缩小倍数满足设计要求,验证了采用该优化设计方法准确设计二级杠杆式力柔顺机构、提高微力加载精度的有效性。

A two-stage lever-type micro-force generator was designed to address the challenges in the calibration system of force sensor to provide accurate micro loads.Initially,the working principle of the micro-force generator was introduced based on the performance comparison among general flexure hinges.Next,the force and energy transmissions were analyzed and a theoretical calculation method to evaluate the minification ratio K was deduced by taking into consideration the deformation of the lever and the offset of the flexure hinge's rotation.To accomplish the aim of achieving a certain minification ratio,the optimization design of the micro-force generator was proposed.Moreover,the response characteristics under different input forces were obtained by performing finite element simulation.Subsequently,a test platform was fabricated to measure the power performance of the micro-force generator.The results show that the largest error between the finite element analysis(FEA)and the theoretical analysis result is 5.501%,whereas that between the experimental result and the theoretical analysis result is 7.391%,the linearity is 2.89%,and loading range of up to 500μN is reached.The results also indicate that the minification ratio K meets the design requirements and verify the validity of applying the optimization method to design two-stage lever-type micro-force generator and improve the accuracy of micro-Newton loads.