Single Access Antenna Pointing Control System Design of TDRS

Abstract

Tracking and data relay satellite system (TDRSS) is one of the hot spots in the development of the aerospace engineering recently. It is a challenging task to design the SA pointing control system with high pointing accuracy to ensure the communication between the tracking and data relay satellite (TDRS) and the user satellites. The SA pointing control system is designed in this paper in detail. Firstly the dynamic model of the TDRS is established using the Lagrange equation. Secondly the control scheme of the TDRS satellite is selected for the main body and the single access antennae. The tracking laws are derived and the antenna's azimuth and elevation angles can be derived by the tracking laws when the TDRS is tracking the user satellites. Thirdly the antenna pointing control concepts are described, and the on-board autonomous control method is designed. The on-board autonomous control scheme is composed of acquisition and autotrack modes. On one hand the acquisition process of the SA antenna is designed. On the other hand, the antenna step logic of the autotrack mode is properly selected. The SA antenna is driven by two-phase permanent magnetic stepper motor, and the mathematical model of the stepper motor is established. Finally, the mathematic simulation of the antenna pointing control system designed in this paper is conducted in the case of taking the user satellite and the ground station as tracking objects according to tracking laws derived before, and the SA antenna pointing performance of the TDRS is demonstrated by the analysis of the simulation results.