A Four-Bar Linkage Designed To Accurately Deploy The Secondary Mirror Of A Large Space-Based Optical Remote Sensing System

A four-bar linkage mechanism for secondary mirror's deployment is designed to satisfy the requirement of high-precision on orbit deployment of space-based optical remote sensing system (SORSS) in this article. The integrally thermal deformation under locking state is simulated by finite element method (FEM). According to the simulation results, the influence of the pre-tightening force of the intermediate hinge and the expansion coefficient of the bars on the post-locking thermal deformation resistance of the entire structure is determined. Based on the FEM results of thermal deformation and the testing results of the actual mechanism at 20 degrees C, the repetitive deployment accuracy of the designed four-bar linkage in orbit is analyzed. The results show that the design meets the requirement of the SORSS, which are that the repetition accuracy of the relative orientation of the primary and secondary mirrors is less than 0.05 degrees, and that the relative position repetition accuracy of primary and secondary mirrors is less than 1 mm.