Hybrid estimation of spacecraft attitude dynamics and rate sensor alignment parameters

This paper deals with attitude dynamics estimation and rate sensor calibration of spacecraft at the same time during a designed maneuver. This study has been motivated from that both estimation of the moment of inertia and calibration of gyros for precision attitude control are usually performed by a pre-designed 3-axis maneuver for them, respectively. Spacecraft attitude dynamics to be estimated consist of the attitude quaternion, the body angular rate, and the moment of inertia. The gyro sensor calibration terms include the gyro scale factor, misalignments and the bias vector. The equations of motion of spacecraft are augmented by estimation and calibration parameters for an extended Kalman filter design to estimate states and measurement parameter errors together. Estimation and calibration results are shown in numerical simulations.