Comprehensive parametric model and decoupling design of a Stewart platform for a large spaceborne optical load

Large spaceborne optical load necessitates an exceptionally serene on-orbit environment to achieve high precision but is subject to micro-vibration and attitude adjustments. At present, the Stewart platform is often adopted and implemented in micro-vibration isolation. However, based on the common model design, the actual decoupling performance of the Stewart platform is still problematic and significantly affects the image quality of the optical load when performing attitude adjustments. Therefore, this work develops a comprehensive parametric model of the Stewart platform to analyze its coupling property. Firstly, a Stewart platform is introduced and its comprehensive dynamic model is established while considering more influential parameters such as the positioning of flexible joints and the detailed equivalent modeling of the legs. Secondly, by comparing the common model and the comprehensive model, the latter significantly reduces errors in the stiffness of the system and modal frequencies. Therefore, relevant parameters are redesigned to meet decoupling requirements and target modal frequency based on the comprehensive model. Using the finite element model and the numerical simulation model of the platform, it is demonstrated that parameters designed based on the comprehensive model effectively decrease the multi-degree-of-freedom coupling degree, and ensure effective micro-vibration control during attitude adjustments.