| 摘要 |
The invention relates to a method of determining the attitude (<, theta , psi ) of a space device. The inventive method comprises the following steps, consisting in: (a) capturing the projections (xmi, ymi) of several stars on an optical star sensor which is mounted on the space device; (b) supplying a reference focal length (fref) for said sensor which is used to convert the star projections (xmi, ymi) captured on the sensor into sensor-star directions (wi) in a reference system which is linked to the sensor; and (c) determining the angular attitude values of the space device in relation to the stars by resolving a system of equations, said system comprising, in particular, the star projections (xmi, ymi) on the sensor and the reference focal length of the sensor as input data. Moreover, the method is characterised in that at least one parameter (D1, , D7) is introduced as an unknown quantity into the equation system. The aforementioned parameter defines a series of focal length deviations and each of said deviations influences the conversion of the projection (xmi, ymi) of a respective star into the corresponding sensor-star (Wi) direction. Furthermore, the invention is characterised in that in step (c), said parameter(s) (D1, , D7) is determined simultaneously with the angular attitude values (?, theta , psi ) of the space device. Thus, the aforementioned focal length deviation parameters are considered as unknown quantities in the system. As a result, uncertainty is reduced with respect to the results of the space device angular attitude values (?, theta , psi ), said uncertainty being caused by lack of knowledge in relation to the aforementioned deviations. |
