Attitude Dynamics Modeling of Nanosatellites with Flexible Deployable Structures

Maxwell is a student built CubeSat scheduled for launch in 2021. The satellite is being designed to carry and deploy a large reflectarray antenna for in-orbit ground communication testing. This paper develops a general model of a satellite with deployable boom-like structures and analyzes the effects of flexing dynamics of such deployables on the attitude performance of a three-axis stabilized CubeSat. The deployables are modeled as point tip masses with stiffness and damping properties tailored to represent those of the actual booms. The model is simulated with typical CubeSat attributes, while the mass and natural frequency of the deployables is varied. Deviations from the nominal position of the deployable are studied under large attitude correction and slewing maneuvers to estimate transient and steady state performances. Influence of mass of the deployable on controller gain constraints is analyzed. The analysis is then applied to the Maxwell CubeSat in a deployed reflectarray antenna configuration to study in-orbit attitude control performance