Design and Implementation of a High Precision Stewart Platform for a Space Camera

Abstract

In order to design and implement a high-precision Stewart platform to precisely adjust the position and posture of the secondary mirror of a space camera, the following measures were taken: firstly, the inverse mathematical model and ADAMS parametric model of the Stewart platform are established, which are the basis of structural optimization design; secondly, the structural parameters of Stewart platform are obtained through structure optimization design in ADAMS after determining the objective function; thirdly, a 50nm resolution driving strut based on brushless DC motor, ball screw, grating ruler and PI closed-loop control law is designed, which strongly guaranteed the six degrees’ resolution of the Stewart platform that mainly consist of 6 such high-resolution driving struts; finally, the accuracy of Stewart platform is tested via dual frequency laser interferometer and photoelectric autocollimator, and the test results show that the displacement resolution of the Stewart platform is 0.2 μ m, and the angular resolution is 1”, which meets the requirements of the index. The Stewart platform has been successfully applied to the space camera by tuning the secondary mirror precisely in 6 degrees of freedom in the optical alignment experiment, which lays a solid theoretical and practical foundation for on orbit application in future.