CONTROL OF FLEXIBLE SPACECRAFT WITH TIME-VARYING CONFIGURATION

This paper is concerned with the dynamics and control of systems with time-varying configuration, such as maneuvering articulated flexible spacecraft. The mathematical model consists of a rigid platform and a given number of retargeting flexible antennas. The mission consists of maneuvering the antennas so as to coincide with preselected lines of sight while stabilizing the platform in an inertial space and suppressing the elastic vibration of the antennas. A perturbation technique permits the derivation of a new control law for systems with time-varying configuration, in which the time-varying terms are relatively small. According to the proposed perturbation method, the control gains consist of zero-order time-invariant gains obtained from the solution of a matrix algebraic Riccati equation, which are valid both during and after the maneuver, and higher-order time-varying gains obtained from the solution of matrix differential Lyapunov equations, which are valid only during the maneuver. The approach is illustrated by means of a numerical example.