Development of a two-DOF piezoelectric posture alignment mechanism with low coupling based on a cross-orthogonal-axis structure

A two-degrees of freedom (DOF) piezoelectric posture alignment mechanism (PAM) with low coupling based on a cross-orthogonal-axis (COA) structure was proposed. The proposed PAM with millimeter-level stroke and nanoscale resolution could realize rotary motions around X-axis and Y-axis based on the stick-slip driving, and the performance of low coupling was also achieved based on the COA structure. Its working principle was introduced and it was designed to achieve the range of rotation angle of 136.4°. The kinematic characteristic of stick-slip motion was analyzed and the step displacement model of the rotor was derived. A prototype of the PAM was fabricated and some experiments were carried out to investigate its performance. The experiment results showed that the X- and Y-axis relative coupling errors are 4.69% and 3.86%, respectively. In addition, the proposed PAM satisfied the requirement of rotation angle of ±2.5° and the angular displacement resolutions achieved 0.09 µrad around X-axis and Y-axis. The proposed two-DOF piezoelectric PAM could be applied to the precision positioning and the adaptive optics system based on its merits of large range, high resolution, low coupling and good carrying capacity.