Hu Qinglei

Adaptive terminal sliding mode finite-time attitude control of spacecraft

An adaptive terminal sliding mode based finite-time control scheme is proposed for the attitude maneuver control of spacecraft, in which the parameters uncertainty and external disturbances are taken into account explicitly. In the proposed controller, a single parameter is adjusted dynamically in such a fashion that no information of uncertainty and/or disturbance is required in advance, and only the boundedness of these is assumed to allow the spacecraft to perform given operations. Lyapunov stability analysis shows that the resulting closed-loop system is proven to be stable and the effect of the external disturbances can be attenuated by appropriately choosing the design parameters. Numerical examples are also presented to demonstrate that the control algorithms developed are not only robust against uncertainty and external disturbances, but also able to achieve the control target in given finite time.

A controller design for spacecraft attitude maneuvering with control saturation based on L 2 -gain

In this paper, a simple robust saturation controller is developed for attitude maneuver of a rigid spacecraft, in which external disturbances and control input constraint are simultaneously taken into account. Precisely, a class of novel nonlinear saturation functions, called power saturation function, is investigated to rigorously enforce actuator-magnitude saturation constraints. Although control smoothness is preserved at all times, it is important to note that the results of this paper that are derived with respect to magnitude saturation place no additional restrictions on the body inertias and make no other small-angle assumptions. The novelty of the approach is in the strategy to construct such a Lyapunov function that ensures not only stability of closed-loop system but also an L2-gain constraint on the performance, which provides a closed-form solution for spacecraft attitude control problem, compared with the conventional methods. Finally numerical examples illustrate the effectiveness and robustness of the proposed controller.

A controller design for spacecraft with control saturation under thrust misalignment

In this paper, an adaptive control approach combined with time-varying sliding mode technique is developed for attitude maneuver of a rigid spacecraft, in which multi constraints are simultaneous considered, such as thruster uncertainties including thrust misalignment and magnitude error, external disturbances, uncertainty of the inertia of the spacecraft, and even the control saturation. By explicitly considering the saturation magnitude of the available control input to the thruster, the maximum value of thrust is used in the designed control law. Finally Lyapunov stability analysis shows that the closed-loop system is stable and numerical examples illustrate that the effectiveness and robustness of using the proposed controller.