Abstract: The problem of singleaxis fast attitude maneuver for a flexible spacecraft is considered in this article. By converting the system into unconstrained model and applying the Minimum Principle, the solution for timeoptimal control is obtained, while the necessary and sufficient condition for the controlswitching time are also established under boundary value conditions. By analyzing the nonlinear equations of the switching time, it is found that if the damping coefficient can be negligible, the control input for timeoptimal attitude maneuver will be a symmetrical function of the maneuver time, and the complexity of solving the nonlinear equations could be reduced greatly. Based on this kind of symmetry, an analytic solution for the rigid body with only one flexible mode is obtained. To overcome the difficulty in solving the nonlinear equations with large number of flexible modes, the system is then transformed into a discretetime model and further simplified to a set of constrained leastsquares problems. Finally, numerical simulation is conducted to demonstrate the effectiveness of the method.

Key words: flexible spacecraft, fast attitude maneuver, timeoptimal control