Abstract: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.