Adaptive integral sliding mode control for rigid spacecraft attitude tracking

When the adaptive sliding mode control (ASMC) technique is utilized for attitude tracking system design, a prior knowledge of the upper bounds of external disturbances and inertia matrix uncertainty is not required for switching gain tuning. However, there may be over-adaptation in current ASMC design in that the generated switching gain is unnecessarily large with respect to the required value. To address such a problem, this paper considers the attitude tracking control of a rigid spacecraft in the framework of ASMC design and proposes an adaptive integral sliding mode control scheme. First, the underlying causes of over-adaptation are analyzed in detail. Then, the influence of initial tracking error on switching gain adaptation is eliminated by exploiting the global sliding mode feature of the integral sliding mode control. The switching gain reduction ability of the proposed strategy is verified by theoretical analysis and simulation results.