Adaptive Attitude-Tracking Control of Spacecraft with Uncertain Time-Varying Inertia Parameters

Although adaptive control schemes for spacecraft attitude tracking are abundant in controls literature, very few are designed to guarantee consistent performance for a spacecraft with both rigid and nonrigid (time-varying) inertia components. Because inertia matrix changes are a common occurrence due to phenomena like fuel depletion or mass displacement in a deployable spacecraft, an adaptive control algorithm that takes explicit account of such information is of significant interest. In this paper, a novel adaptive attitude control scheme is presented for a spacecraft with inertia matrix parameters that have both unknown rigid components and only partially determined variable components. The proposed controller directly compensates for inertia variations that occur as either pure functions of the control input, or as functions of time. For the particular case of an input-dependent inertia matrix, a bounded control solution is ensured by placing some mild restrictions on the initial conditions and by empl...