Relative orbit estimation and formation keeping control of satellite formations in low Earth orbits

A new relative orbit estimation method and practical control scheme for satellite formation keeping is developed. We present the general formation description method based on the relative orbital elements and employ the extended particle filter for the relative orbit estimation using the relative distance, elevation, and azimuth measurements. The stability of the formation configuration is analyzed in the presence of the J2 perturbation and atmospheric drag. We propose a new control scheme for formation keeping, including the triple-impulse strategy for the in-plane motion, the single-impulse maneuver for the cross-track motion, and the time-optimal aerodynamic control for the along-track separation. The full analytical fuel-optimal triple-impulse solutions are then derived, which do not cause additional along-track drift compared with the conventional dual-impulse method. Effects of the thruster errors are also analyzed. Furthermore, the time-optimal aerodynamic control law for the along-track drift is presented. Simulation results show that the relative position estimation errors are within 2 x 10(-2) m, and that of the relative velocity estimation are within 1 x 10(-4) m/s. Moreover, the triple-impulse strategy is simple and effective, and the along-track aerodynamic control precision is under 50 m. (C) 2012 Elsevier Ltd. All rights reserved.