Application of Kalman filtering to gyroless attitude determination and control system for environmental satellites

A highly accurate, gyroless, attitude determination and control system for advanced environmental satellites is developed and validated by analysis and simulation. The features of this approach include an algorithm to determine satellite rates directly from the apparent motion of the stars on the focal plane and an extended square root Kalman filter algorithm to estimate attitude. This system is appropriate for satellites with slowly varying attitude dynamics and high priority accuracy. Missions of this variety are meteorology, Earth resources, communication and surveillance. Appropriate attitude control techniques are reaction wheel and bias momentum system providing three-axis pointing control. The simulation results of the attitude estimation with various noise statistics on the star data are shown. The results of this approach are also compared with the gyro-aided system in accuracy of the attitude estimation process. The results show that the concept presented in the paper does work and that the accuracy would meet a large variety of satellite mission requirements. The major result of this research is the realization of a space-capable stellar attitude determination system which does not require a rate gyro package.