基于压电陶瓷驱动的六自由度空间光学拼接系统

由于加工工艺的限制，大口径空间光学系统通常由多个子镜拼接而成。为了保证系统的成像质量，每个子镜都需要在毫米级范围内实现微米级精度的运动调节。提出了一种串并混联的、由压电陶瓷（PZT）驱动的六轴高精度定位系统。与常见的Steward平台相比，该方案具有结构紧凑、运动学简单等特点。为了同时实现大行程和高分辨率，采用桥式放大器对PZT行程进行放大，采用柔性铰链消除运动过程中的摩擦和间隙，分析了放大器在两种外部负载下的性能，并根据实际应用情况对放大器进行了设计。此外，还发现了在执行机构的输出端必须使用位移传感器，以消除柔性机构中常见的输入耦合现象。设计的可行性通过有限元分析和实验研究进行了验证。

A PZT Actuated 6-DOF Positioning System for Space Optics Alignment

Since the restraint of the fabrication technology, the large aperture space optical mirror is always spliced by several small segments rather than being fabricated monolithically. To guarantee the imaging quality of the system, each segment needs to be aligned at micron-level precision within millimeter-level range. For this purpose, a Piezoelectric (PZT) actuated 6-axis high-precision positioning system which consists of three serially connected parallel mechanisms was proposed. Compared with previous six degrees of freedom (6-DOF) positioning solutions such as a Stewart platform, the proposed design features relatively compact structure and straightforward kinematics. To realize long stroke and fine resolution simultaneously, the bridge-type amplifiers were employed to enhance the stroke of the PZT actuation and the flexure hinges were utilized to eliminate the friction and backlash. The performance of the amplifier under two kinds of external loads was analyzed so that the amplifiers could be designed according to the application conditions. Furthermore, it was found that the displacement sensors must be employed at the output end of the actuation module to eliminate the input coupling which commonly existed in the compliant mechanisms. The feasibility of the design was validated by finite element analysis (FEA) and experiment study.