Abstract
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.
Highlights
In recent years, the development of large orbiting structures to support Earth observation and mobile communication technology has been witnessed [1,2,3]
The large satellite antennas (LSAs) is fixed on the satellite body, as shown in Figure 1, and the attitude dynamics include two components: the attitude dynamic model of the flexible satellite and the antenna pointing in the satellite body coordinate system
The autonomous pointing problem of a large satellite antenna, which is achieved through satellite attitude maneuvers, is addressed in this paper
Summary
The development of large orbiting structures to support Earth observation and mobile communication technology has been witnessed [1,2,3]. An active disturbance rejection control for the antenna pointing control of a large flexible satellite system was proposed in [12], and the inner and outer loops of the control system were studied to improve pointing accuracy and rotation speed. If the antenna is large with high moments of inertia and low structural frequency, the fundamental frequency of the whole satellite–antenna system will be mainly driven by the antenna In this case, the bandwidth of APM-based pointing control loop is not much higher than that of the satellite attitude control loop, which will lead to complicated attitude dynamic coupling problems. The adaptive control approach provides an ideal solution to deal with this problem since it can handle online estimation for uncertain and unknown system parameters To address these challenges, frequency-domain methodology is used to design the autonomous pointing controllers in this paper. The proposed control approach can avoid excessive complexity of the control laws, and reduce the dependency of the controller on the knowledge of the system parameters
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