Abstract
Attitude determination using earth sensors has an advantage of smaller volume compared with star trackers. The methods to determine attitude with earth sensors proposed so far are based on matching the detected known land with images or map data. Thus it can be used only in the situation some land can be seen. To resolve this problem, we have developed several methods to detect relative attitude, that is attitude shift, which does not require known land. In this paper, a new method besides suggested ones is proposed which can achieve higher accuracy. By estimating the position of unknown objects using geometrical analysis, it is possible to predict the direction to the object from the earth sensor frame, at the time after a certain period. Comparing this and actual object direction, we can calculate the relative attitude. As a result of numerical simulations, the proposed method is roughly ten times more accurate than the existing method.
