The solar system objects are fast moving objects, needing to build accurate dynamical models in order to make ephemerides and to predict the positions of these objects in the future. More, the building of such dynamical models helps to understand the formation and the evolution of the objects of the solar system. For that purpose, astrometric observations of their positions are made since years. Because of the progress of the observational techniques, the astrometric accuracy of the observations is increasing, years after years.