Study On Bias Momentum Micro-satellite Attitude Control System

Since the 80's 20 centuries, the micro-satellite techniques have made great progress in recent years, the development of which is a significant trend in the aerospace area.The development of the micro-satellite techniques have been a revolution which influence our lifestyle. As a key section of micro-satellite, the micro-satellite attitude control system should have the feature of simple configuration, light weight, high reliability and low cost. In this paper, taking a specific micro-satellite'attitude control system as an example, the method of micro-satellite attitude determination,magnetic attitude control and their hardware realization are studied. The main work done is as follows:At first, Euler Angle and Quaternion are used to describe the micro-satellite status. Then the attitude kinematics and dynamic models are established. The mathematical models of environmental torques are also discussed and manifested. Meanwhile, the transition between Euler Angle and Quaternion has been given. The pertinent definition has also been indicated. It's the foundation of the extending research.The attitude sensor's measure theories for attitude determination and magnetorquers for active magnetic attitude control are important parts of the satellite attitude control system. They influence the measure precision and the control effect to a certain extent. Moreover, the attitude sensor's measure theories for attitude determination are manifested and illustrated, as well as the the work theory of magnetorquers for active magnetic attitude control. The the characteristic of magnetic torque are also analyzed.Research about attitude determination: Discussing the principle and process of EKF (extended kalman filter). Based on state estimation, an extended kalman filter algorithm by fusing the data from sun sensor, magnetic sensor and infrared earth sensor is built. The MRPs and SSUT definitions and the transition between MRPs and Quaternion have been introduced. Based on the MRPs(Modified Rodrigues Parameters) and SSUT(Spherical Simplex Unscented TransforMation), an unscented kalman filter is designed by using the sun sensor, magnetic sensor. All of these attitude determination algorithms are demonstrated by simulation.Research about active magnetic attitude control: the velocity damping magnetic control of satellite during the initial entering orbit is discussed (minus B-dot control algorithm). Based on Quaternion, a slidingmodel control algorithm is design for the biased momentum satellite. To limited and eliminate the serious influence of bias momentum wheel invalidation, the magnetic control algorithm for gravity gradient micro-satellite is studied too. The adaptive control law based on Quaternion is provided to keep the control system's continuity. All of these control algorithms are demonstrated by simulation, too.