Adaptive Attitude Tracking Control with L2-gain Performance for an Orbiting Flexible Spacecraft

This paper treats the problem of nonlinear adaptive attitude tracking control of an orbiting flexible spacecraft. It is assumed that the system parameters are unknown and the truncated model of the spacecraft has finite but arbitrary dimension. An adaptive sliding mode control law is derived for a threeaxis stabilized spacecraft attitude tracking control system. The control gains are designed by solving a linear matrix inequality (LMI) problem to achieve a prescribed L2-gain performance criterion. The external torque disturbance/parametric error attenuation, with respect to the performance measure, along with control input penalty are ensured in the L2-gain sense. Lyapunov analysis is employed to show that the closed-loop system is asymptotically stable and the effect of the external disturbances/parametric error on the tracking error can be attenuated to any prescribed level. Simulation results show the effectiveness of the control scheme.