Adaptive Sliding Mode Control Laws for Attitude Stabilization of Flexible Spacecraft With Inertia Uncertainty

In this paper, attitude stabilization control for flexible spacecraft with inertia uncertainty is considered. First, an adaptive law is constructed to estimate the upper bound of a certain function related to the inertia uncertainty. Then, based on the proposed adaptive law, an adaptive sliding mode finite-time state feedback control law is established for the case where the flexible modal variables are measurable. Furthermore, an adaptive sliding mode control (SMC) law based on observers is proposed for the situation where the flexible modal variables are unmeasurable. To verify the effectiveness of the presented control laws, simulations are performed in the presence of inertia uncertainty. The simulation results show that the proposed control laws can attenuate the effect of inertia uncertainty successfully, and the attitude states can be stabilized in finite time without unwinding phenomenon by the proposed SMC laws.