Attitude Tracking Control of Spacecraft with Time-Varying Inertia Matrix

This paper investigates the problem of attitude tracking control for a nonrigid spacecraft subject to time-varying inertia matrix and external disturbances. Based on the deployable spacecraft with both fuel depletion and mass displacement, the time-varying inertia matrix is characterized with both rigid components and time-dependent components. Not only the direct influences of the fuel depletion and the mass displacement, but also the resulting change of center of mass (CM) are taken into account during the characterization. And the time-varying inertia matrix is applied to the mathematic model of the nonrigid spacecraft's dynamics. Then, an adaptive attitude tracking control algorithm is proposed for the nonrigid spacecraft. The proposed controller directly compensates for inertia variations and achieves high control accuracy and good system robustness. Furthermore, a theoretical analysis of the system stability is also presented. Finally, numerical simulations are carried out to illustrate the effectiveness and superior control performance of the proposed control scheme.