一种高精度大行程2R1T并联定位平台

A 2R1T parallel positioning platform with high accuracy and large working stroke

为了解决传统压电陶瓷驱动器所固有的高精度与大行程的矛盾,提出了一种新型可直接外力驱动的三自由度并联精密定位平台,利用压电直线电机直接驱动即可实现大行程与高精度定位。首先,分析了柔性铰链结构参数对其作动行程的影响机理,在此基础上设计了大行程圆柱柔性铰链,并对大行程圆柱柔性铰链的结构参数进行了模糊优化设计;接着,采用两个平移副和一个一体化、大行程圆柱形柔性铰链构建了并联分支链路,采用3条并联支路设计了2R1T并联精密定位平台,并通过坐标齐次变换方法构建了并联平台的运动学模型,推导出了并联平台位姿正反解;最后,对2R1T并联定位平台开展了实验研究。实验结果表明所设计的2R1T并联定位平台具有良好的运动同步性和重复性,利用压电直线电机的步进运动模式可实现精密定位,其平动定位分辨率为0. 09μm,转动定位分辨率分别为0. 8μrad、0. 9μrad和1. 0μrad;利用压电直线电机的连续运动模式可实现大行程空间定位,其平动工作行程为120 mm,转动工作行程分别为6. 18°、6. 74°和6. 58°。借助于压电直线电机的不同工作模式实现了并联平台的精密定位和大行程工作空间两个关键指标,为进一步研究2R1T并联机构的动态性能、精密定位及控制规律的实现等提供了重要的理论价值和实践基础。

The traditional piezoelectric ceramic actuator has the inherent contradiction of high precision and large working stroke.To solve this problem,a novel 2 R1 T parallel precision positioning platform is proposed.It can be driven by the external force directly.The high precision and large working stroke can be both realized by the piezoelectric linear motor.Firstly,the influence mechanism of the structure parameters on actuation stroke is analyzed.Based on the analysis result,the flexible cylindrical flexible hinge with large working stroke is developed.Its structure parameters are optimized by using the fuzzy optimization method.Secondly,the 2 R1 T parallel precision positioning platform is established with three parallel branches,which are consisted of the two translation pairs and the flexible cylindrical flexible hinge.The kinematics model of the parallel platform is discussed by the coordinate homogeneous transformation method.The forward and inverse position solutions of the 2 R1 T platform are also obtained.Finally,experiments are implemented to evaluate the performance of the parallel platform.Experimental results show that the 2 R1 T parallel platform has advantages of synchronization and repeatability of positioning.By using the step motion mode of the piezoelectric motor,the parallel platform can realize the precise positioning.Its translation resolution is 0.09μm,and the rotation resolutions are 0.8μrad,0.9μrad and 1.0μrad,respectively.In the continues motion mode of the piezoelectric motor,the large working stroke of the translation and rotation are 120 mm,6.18°,6.74°and 6.58°,respectively.The key performance indicators of precision positioning and large working stroke of the parallel platform are both realized based on different motion mode of only one piezoelectric motor.All basic research contents have important theoretical value and experiment foundation for the further study of the dynamical performance,the realization of precise positioning and control law of the 2 R1 T parallel platform.