Simulation of Multibody Spacecraft Reconfiguration through Sequential Dynamic Equilibria

Abstract

This paper describes a novel hybrid-control strategy to reconfigure multibody spacecraft from one shape to another in such a way that passively stable system dynamics enable both low control effort and a high degree of robustness. This approach treats reconfigurable spacecraft systems as multibody kinematic mechanisms with controllable kinematics and takes advantage of ambient force fields in the space environment (gravity gradient, magnetism, etc.) along with passively generated, non-contacting forces on the spacecraft (such as those from permanent magnets) to drive the reconfiguration maneuver to one stable dynamic equilibrium after another, in sequence. The use of kinematic constraints and passive dynamics adds robustness, while the stepwise nature of the reconfiguration maneuver provides many safe-hold points for verification regardless of transient dynamics. The focus on kinematic constraints lends itself well to Udwadia and Kalaba’s technique for generating equations of motion. This work details the augmentation of the Udwadia-Kalaba equations with quaternion states and Euler’s equation for fully 3D rigid body motions, as well as the development of a simulation environment and computational tools for exploring sequential-equilibrium reconfigurations.