Comparison of two methods in satellite formation flying

Recently, the research of dynamics and control of the satellite formation flying has been attracting a great deal of attentions of the researchers. The theory of the research was mainly based on Clohessy-Wiltshire's (C-W's) equations, which describe the relative motion between two satellites. But according to some special examples and qualitative analysis, neither the initial parameters nor the period of the solution of C-W's equations accord with the actual situation, and the conservation of energy is no longer held. A new method developed from orbital element description of single satellite, named relative orbital element method (ROEM), was introduced. This new method, with clear physics conception and wide application range, overcomes the limitation of C-W's equation, and the periodic solution is a natural conclusion. The simplified equation of the relative motion is obtained when the eccentricity of the main satellite is small. Finally, the results of the two methods (C-W's equation and ROEM) are compared and the limitations of C-W's equations are pointed out and explained.