考虑减速机背隙的3-RRR并联机构的运动学标定

Kinematic Calibration of 3-RRR Parallel Mechanism Considering Reducer Backlash

为了提高宏动并联平台的定位精度,推导了考虑减速机背隙的3-RRR并联机构误差模型,同时建立不考虑减速机背隙的误差模型用于对比,以验证该模型的有效性;通过实验测量末端平台位姿误差并分别辨识两个误差模型参数,根据距离反比法进行空间插值实现误差补偿并完成运动学标定.根据标定结果修正逆运动学模型,通过测量末端平台位姿误差分布可知,文中提出的考虑减速机背隙的误差模型优于不考虑减速机背隙的误差模型.文中提出的考虑减速机背隙的运动学标定提高了并联机构的定位精度,为该类并联机构用于高精密宏微结合提供了基础.

In order to improve the positioning accuracy of macro parallel platforms, firstly, an error model of 3-RRR parallel mechanism, which takes into consideration the reducer backlash, is derived, and the effectiveness ofthe proposed model is verified through a comparison with the error model without considering the reducer backlash.Secondly, an experiment is carried out to measure the attitude error of end-effector and to identify the parameters ofthe two above-mentioned models. Then, IDWM is employed to realize spatial interpolation and error compensation,followed with a kinematic calibration. Finally, the inverse kinematic model is corrected according to kinematic calibrationresults. It is found from the measured posture error distribution of end-effector that the proposed error modelconsidering reducer backlash is superior to that without considering the backlash. The kinematic calibration consideringreducer backlash enhances the positioning accuracy of parallel mechanism and provides a theoretical foundationfor the development of high-precision macro-micro parallel mechanisms.