Large Antenna Servo System Modeling And Wind Disturbance Rejection Control

The large antenna with a high gain and a narrow beam plays an important role in fields such as astronomical observation, aerospace measurement and control. The frequency increased continually in order to improve the antenna’s resolution, and thus a higher pointing precision is required. For the large windward area and low natural frequency, the pointing accuracy of the large antennas operating in the open air could be gravely influenced by the wind gust disturbances, which becomes one of the crucial factors to limit the improvement of the large antenna performance.The wind interference control strategy and method are presented, for decreasing the pointing deviation, caused by the flexible deformation of antenna structure under wind disturbance. Firstly, while analyzing the pointing errors from structure deformation, the flexible body dynamic model for large antenna, or control-oriented antenna model, is derived with model reduction technique. Secondly, an LQG(Linear-Quadratic-Gaussian) controller based on above model is designed to reject wind disturbance for high pointing accuracy. Furthermore, the wind gust disturbance rejection properties and dynamic properties are analyzed with a 7.3m test antenna. Finally, an adaptive sliding mode controller with disturbance observer is designed for the antenna with uncertain parameters, with which the tracking performance of the antenna models for different pitch angles and uncertain damping are tested. Compared with the traditional PID controller, the results show that the wind gust disturbance rejection properties of the LQG servo control system could be improved remarkably, and the robustness and tracking performance are improved with the adaptive sliding mode controller.