Autonomous determination of orbit for probe around asteroids using unscented Kalman filter

The observed images of the asteroid and the asteroid reference images are used to obtain the probe-to-asteroid direction and the location of the limb features of the asteroid in the inertial coordinate. These information in combination with the shape model of the asteroid and attitude information of the probe are utilized to obtain the position of the probe. The position information is then input to the unscented Kalman filter (UKF) which determines the real-time orbit of the probe. Finally, the autonomous orbit determination algorithm is validated using digital simulation. The determination of orbit using UKF is compared with that using extended Kalman filter (EKF), and the result shows that UKF is superior to EKF.