Shunan Wu

Robust Finite-Time Control for Flexible Spacecraft Attitude Maneuver

The robust finite-time control for a flexible spacecraft attitude maneuver in the absence and presence of inertia uncertainties and external disturbances is investigated in this paper. The finite-time controllers, based on the Lagrange-like model and nonsingular terminal sliding mode technique, which guarantee the convergence of attitude maneuver errors in finite time rather than in the asymptotic sense, are proposed to perform an attitude maneuver. By constructing a particular Lyapunov function, the convergences of the proposed controllers for the closed-loop systems are proven theoretically. The robustness problem associated with inertia uncertainties and bounded disturbances is addressed. Numerical simulations are finally provided to illustrate the performance of the proposed controller by comparing it with the conventional sliding mode control. The finite-time controller demonstrates superior performance, such as fast convergence performance, ideal robustness, and effectiveness in suppressing vibration.

Robust Adaptive Learning Control for Spacecraft Autonomous Proximity Maneuver

The robust adaptive learning control for spacecraft autonomous proximity is investigated in this paper. The relative motion dynamics is firstly proposed and transformed into the state space representation. An adaptive learning controller that allows performing autonomous proximity maneuvers in the presence of uncertain orbital parameters is then developed. The unknown disturbances are considered, and a modified adaptive learning controller is therefore designed in the presence of uncertain parameters and unknown disturbances. The asymptotic stability of the proposed controllers for the closed-loop systems is proven based on the Lyapunov theory. Different numerical results are finally provided and compared to illustrate the performance of the proposed adaptive learning controllers.

Autonomous Pointing Control of a Large Satellite Antenna Subject to Parametric Uncertainty

With the development of satellite mobile communications, large antennas are now widely used. The precise pointing of the antenna’s optical axis is essential for many space missions. This paper addresses the challenging problem of high-precision autonomous pointing control of a large satellite antenna. The pointing dynamics are firstly proposed. The proportional–derivative feedback and structural filter to perform pointing maneuvers and suppress antenna vibrations are then presented. An adaptive controller to estimate actual system frequencies in the presence of modal parameters uncertainty is proposed. In order to reduce periodic errors, the modified controllers, which include the proposed adaptive controller and an active disturbance rejection filter, are then developed. The system stability and robustness are analyzed and discussed in the frequency domain. Numerical results are finally provided, and the results have demonstrated that the proposed controllers have good autonomy and robustness.