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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. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the spacecraft attitude tracking control problem. Two robust sliding mode controllers based on the quaternion and Lagrange-like model are proposed to solve this problem both in the absence of model uncertainties and external disturbances as well as in the presence of these. The controllers can guarantee the convergence of attitude tracking errors in finite time rather than in the asymptotic sense, where time tends to infinity. By constructing a particular Lyapunov function, the convergences of the proposed controllers for the closed-loop systems are proven theoretically. To alleviate the chattering phenomenon while at the same time guaranteeing the finite convergence during the process of attitude tracking, a new function is introduced into the controller. Numerical simulations are finally provided to illustrate the performance of the proposed controllers. [Copyright &y& Elsevier]

This paper investigates the attitude control problem in the presence of wheel low-speed friction and external disturbances. The critical issues surrounding wheel friction are firstly discussed, and the spacecraft attitude model and wheel friction model are introduced. A friction observer that can effectively estimate the friction torque is developed. An observer-based sliding mode controller, to perform attitude maneuver, is then proposed. By constructing a particular Lyapunov function, the stability and performance of the proposed controller for the closed-loop systems is discussed theoretically. Numerical simulations are finally provided, and the results have demonstrated that the friction is compensated by the observer and the proposed controller has better transient and steady-state performance. [ABSTRACT FROM AUTHOR]

Abstract This paper investigates the multi-objective attitude tracking problem of a flexible spacecraft in the presence of disturbances, parameter uncertainties and imprecise collocation of sensors and actuators. An integrated robust H∞ controller, including an output feedback component and a feedforward component, is proposed, and its gains are calculated by solving Linear Matrix Inequalities. The output feedback component stabilizes the integrated control system while the feedforward component can drive the attitude motion to track the desired angles. The system robustness against disturbances, parameter uncertainties and imprecise collocation is addressed by the H∞ approach and convex optimization. Numerical simulations are finally provided to assess the performance of the proposed controller. Highlights • The attitude tracking control of flexible spacecraft is a multi-objective problem. • An integrated robust H∞ controller is proposed to perform attitude tracking. • The proposed controller is robust to imprecise collocation of sensors and actuators. • The system robustness is addressed by the H∞ approach and convex optimization. [ABSTRACT FROM AUTHOR]