Research Of The Attitude Control Method Using Gravity Gradient Momentum

The altitude determination of spacecraft has always been a hot problem in spaceflight and aero aviation. With the miniaturization of satellites, especially the huge economic benefits and outstanding impacts of modern mini-satellites, modern mini satellites have entered onto a new era. The application of gravity gradient in the attitude control system of mini-satellites provides an advantaged tool for the development and research of the miniaturization of satellites. At the same time, gravity gradient is also a hot problem in space research. Therefore, this thesis is focused on the key problem of the attitude control method using gravity gradient momentum, which can provide valuable reference for the development of space station of our country.This thesis makes a concise introduction on the research and development of gravity gradient satellites from an international viewpoint, and their application prospect, illustrates the principles and methods used in the dynamic modeling of satellite attitude, discusses the main methods for satellite attitude determination, and builds the methodology of the application of GPS in satellite attitude determination. The GPS ambiguity is especially paid attention to. The existence interval of the integral ambiguity on finite baseline length in double difference observations is determined. From the comparison of GPS attitude measurement and GPS kinematical surveying, the characteristics of GPS attitude measurement are discovered. The gravity gradient momentum model is set up from the principles of satellite attitude stabilization using gravity gradient momentum, and then the predicative filtering is applied in satellite attitude prediction and simulations are made. The principle and means in current satellite attitude control are analyzed and compared. With modern control theory, the performance and stability of gravity gradient attitude control system are analyzed, and the author finds that the best control system for gravity gradient satellite adopts the Control Momentum Gyro (CMG) and gravity gradient as the control momentum and three-axes stabilization as its control system.