Linear Structural Dynamics and Tip-Vane Attitude Control for Square Solar Sails

Abstract

This Paper presents a linear model for a square solar sail spacecraft containing four pretensioned triangular sails supported by four flexible diagonal booms. The structural dynamics of the stretched sails and diagonal booms is explored by using a two-stage model including a static finite element or analytic model to solve for the sails in-plane stresses due to prestretching and a dynamic finite element model to calculate the in- and out-of-plane deflections of the interconnected sails and booms. The dynamic finite element model takes into account the effect of in-plane stresses, which are calculated by the static finite element or analytic model. Once the structural dynamic model is established, different modal cost analyses are used to evaluate and rank elastic modes of the solar sail. Two attitude controllers are developed for the solar sail, and the controller/structure interactions are studied using the linear model and considering an attitude maneuver.