关键词: 精密传动, 六自由度, 压电制动器, RPY 角, 运动特性, 坐标变换

Abstract:

In order to meet the requirement of degree of freedom and long distance in the precision manufacturing field,a micro transmission platform with six degrees of freedom is designed on the basis of spatial mechanism.This platform is driven by piezoelectric ceramic and oriented by flexible hinge.Aiming at the small output displacement of piezoelectric ceramic,a bridge mechanism is designed to enlarge its output displacement,and the wire cuttingmethod is employed to accomplish a one- time processing of transmission platform.Thus,a one- piece transmissionplatform with long distance is obtained.Moreover,a supplemented and corrected RPY (Roll- Pitch- Yaw) anglepose description method is put forward by means of the homogeneous coordinate transformation,and then it is usedto analyze the motional characteristics of the transmission platform.Consequently,a kinematics model of microtransmission platform is established according to the virtual work principle and the coordinate transformation theory,and thus the mapping relationship between the moving displacement of transmission platform and the driving dis-placement of piezoelectric ceramics is obtained.Besides,the static stiffness in six directions of micro transmissionplatform and their change rules are also arrived at.Finally,a finite element simulation on the one- piece transmi-ssion platform is performed by using the software ANSYS12.0,and an experimental platform is put up to carry outthe corresponding experiments.As a result,the correctness of the proposed theoretical model and the rationality ofthe proposed platform are verified by means of the comparative analysis among theoretical,simulation and experi-mental results.

Key words: precision transmission, six degrees of freedom, piezoelectric actuators, RPY angle, movement charac-teristic, coordinate transformation