Title

Variable Structure Model Reference Adaptive Formation Control of Spacecraft

Document Type

Article

Abstract

Based on the variable-structure model reference adaptive control theory, a new output feedback control system for the formation flying of satellites is designed. A leader satellite is moving on an elliptic orbit. The objective is to control a follower satellite so that it follows a prescribed path with respect to the leader satellite. The nonlinear formation model of the satellites includes unknown parameters and disturbance forces, and it is assumed that only the relative position of the follower spacecraft with respect to the leader spacecraft is measured for feedback. A variable-structure model reference adaptive control system is derived that includes relays and linear first-order filters. In the closed-loop system, including the adaptive control system, the follower satellite tracks given reference trajectories, and all state variables remain bounded. The modulation functions of the relays are functions of certain auxiliary signals and the bounds on the uncertain parameters and unknown signals. A simplified adaptive control law is obtained by the choice of constant modulation functions. Simulation results show that the closed-loop system, including the simple control law, has good transient behavior and robustness to parametric uncertainties and unknown signals.

Disciplines

Aeronautical Vehicles | Aerospace Engineering | Controls and Control Theory | Electrical and Computer Engineering | Space Vehicles