Dynamic modeling and analysis of large axially deployable spacecraft under gravity gradient

Many spacecrafts are designed with extendible, deployable, or inflatable appendages to achieve various desirable ultra-large configurations in space, which brings new challenges to the dynamic modeling and analysis of large spacecrafts. In this paper, flexible vibration and attitude angle coupling dynamic behavior of an axially deployable spacecraft considering the effects of gravity gradient are investigated. First, an improved spacecraft's coupled dynamic model is constructed based on the Euler–Bernoulli beam theory and Hamilton's principle while accounting for the axial motion and gravity gradient for the first time. Then, a practical deployment strategy is adopted to resolve the problem of speed residue. In addition, the effects of gravity gradient force and extension motion on deploying process, long-time evolution of the flexible vibration, and attitude motion of the spacecraft are investigated. The results indicate that the gravity gradient force and the coupling effects may alter the stability of the spacecraft system with a short deploying time, and result in a new absolute minimum value for the flexible vibration. This investigation provides constructive guidance for the attitude adjustment scheme and deployment strategy design of large-scale deployable spacecrafts.