Damage Model Iterative Approximation Approach for Reflector Identification Under Uneven Cable Degradations

During long-term on-orbit operation, mesh reflectors exposed to harsh environments may experience nonuniform cable stiffness degradations due to cable creep and microslippage at joints, leading to significant deterioration in reflector accuracy. Existing reflector identification methods, such as photogrammetry, often face challenges in onorbit applications due to their reliance on additional equipment. To address the problem, a novel damage model iterative approximation (DMIA) method is proposed for identifying mesh reflectors experiencing nonuniform cable stiffness degradations. In this method, the changes of selected cable tensions are monitored. If tension changes exceed a threshold, the DMIA approach is triggered. In each iteration step, the sensitivities of cable tensions to stiffness degradations are derived, and the most likely degraded cable is determined based on correlation analysis, and the damage submodel is updated accordingly. Finally, the damage model of the mesh reflector is achieved, and its reflector accuracy is identified timely. Another merit of the approach is that cable tensions could be evaluated timely, which provides critical parameters for subsequent shape adjustment. Simulation on a 3-m-diameter reflector and experimental validation by photogrammetry on a 1.5-m-diameter reflector confirm the effectiveness of the DMIA in identifying mesh reflectors under nonuniform cable stiffness degradation.