双柔性平行六连杆微动平台结构的设计及测试

采用直圆型柔性铰链设计了承载能力较大的双柔性平行六连杆微纳定位平台,并对其性能进行了测试。基于柔性铰链经典刚度公式计算了直圆型柔性铰链转动刚度,推导了双柔性平行六连杆微动平台在运动方向的整体刚度函数;建立了平台的动力学模型,得到了平台的固有频率解析式。基于静动态特性优化设计了双柔性平行六连杆微纳定位平台,得到了平台的优化参数。基于激光干涉仪和多普勒激光测振仪建立了平台的静动态特性测试系统。对微纳定位平台进行了试验和测试,结果显示:刚度的理论计算值为7.92N/μm,试验值为7.44N/μm,误差为6.5%;固有频率的理论模型值为349.9Hz,实验值为342.2Hz,误差为2.3%。空载和加载为250、500、2 000、2 250、2 500g时的平台位移表明加载不均匀会对平台输出位移产生较大的影响,当加载为2 500g时,不均匀加载对位移的影响量约为均匀加载的5倍。此外,平台最大位移为56.59μm。重复定位精度测试显示,在施加电压50、100、150V时,定位平台在同一输入电压下的位移最大偏差为0.896μm。实验结果表明,建立的双柔性平行六连杆的刚度和固有频率计算模型是正确的,设计的微动平台的最大位移及精度可满足设计要求。

Design and experiments of micro motion platform based on a pair of flexible parallel six-bar linkages

A micro motion platform with a pair of flexible parallel six-bar linkages and larger bearing capacity was designed based on a right circular flexure hinge and its performance was tested. The rotational stiffness of the right circular flexure hinge was calculated by classical stiffness equation, then the stiffness equation of the platform with a pair of flexible parallel six-bar linkages in a motion direction was deduced. The dynamic model of the platform was established with Lagrange equation, and the analytical formula of natural frequency of the platform was deduced. The micro motion platform was designed and optimized and the parameters of the flexure hinge were optimized based on the static and dynamic characteristics. A test system for static and dynamic characteristics of the micro motion platform was established based on a laser interferometer and a laser Doppler vibrometer. The test results show that the error of stiffness is 6.5% between the theoretical value 7.92 N/μm and the experiment value 7.44 N/μm, and the error of nature frequency is 2.3% between the theoretical value 349.9 Hz and the experiment value 342.2 Hz. The displacements under no-load and the loading of 250, 500, 2 000, 2 250, 2 500 g indicate that the uneven loading has larger influence on the displacement of the platform. When the loading is 2 500 g, the effect by uniform loading is about five times as much as that of nonuniform loading. The max displacement of the platform is 56.59 μm. Moreover, the repeated accuracy of positioning is tested and the results indicate that the max displacement deviation is 0.896 μm on the voltage of 50, 100, 150 V. It concludes that the calculation models of the stiffness and natural frequency are correct and the max displacement and accuracy match the design demand.