ANGULAR RATE ESTIMATION FOR GYROLESS SATELLITE ATTITUDE CONTROL

This paper presents the results of a study to develop and evaluate an attitude and attitude rate estimation technique for a multi-body spacecraft that includes a real time angular rate calculation from the system dynamic model and a Kalman filter estimator with attitude sensor updates provided by star trackers. The performances of this method, dynamic gyro, are compared with that of rate gyros and the effects of primary error sources in the dynamic model are analyzed. It is shown that the corrections provided by a star tracker based Kalman filter make the system robust to measurement and parameter knowledge error sources. This method provides an imperfect but operative means of estimating multi-body spacecraft angular rates. This method is ideally suited to a spacecraft designed specifically for its implementation with precise internal sensors and mechanism to monitor spacecraft parameters and integrated external torque estimation modeling. 1