Dynamics And Control Of Two Types Of The Non-Keplerian Orbits

With thrusts provided by advanced propulsion systems such as solar sails, it is possible for spacecraft to move along non-Kepler orbits such as heliocentric displaced orbits and the pole-sitter orbits. Possessing excellent positions in space, these orbits has the potential to provide an ideal platform for plenty of missions like deep-space communication relay, space weather monitoring, and solar physics, etc. Therefore it is of great signification to study the dynamics of control of these two types of non-Kepler orbits.In the first place, station-keeping control of solar sail spacecraft flying along the heliocentric displaced orbit is analyzed. In order to improve the engineering performance of the solar sail, the station-keeping control process is divided into a transient phase and a station-keeping phase based on the different advantages of the solar sail and the solar electric propulsion. Meanwhile, the solar sail is equipped with reflectivity control devices to avoid under-actuated problem existing in regular sails. Besides, in order to overcome the non-affine and nonlinear properties of the orbital dynamic equations of solar sail spacecraft, this dissertation utilizes active disturbance rejection control technology to provide an effective solution for station-keeping control problem of solar sail spacecraft flying on the heliocentric orbit.Secondly, to achieve high-precision spacecraft formation, the controller design method for spacecraft formation flying using continuous low thrust in heliocentric displaced orbit is discussed. This dissertation first derives dynamic model of spacecraft formation flying using continuous low thrust. Furthermore, a clear and practical control method on the basis of linear active disturbance rejection control is presented. At last, numerical simulation results indicate that the proposed method is effective in the presence of system uncertainties, initial injection errors and perturbations of the eccentric nature of the Earth’s orbit. Besides, the formation keeping precision is in the submillimeter range, which satisfies the accuracy requirement of "LISA Pathfinder" mission.Finally, the pole-sitter mission is investigated. This part begins with a dynamic model of a spacecraft moving on an Earth pole-sitter orbit within the context of the circular restricted three-body problem. The position and velocity transformation relationship between the circular restricted three-body problem reference frame and the inertial, equatorial reference frame is then derived. Since the manifold-like trajectory of the Earth pole-sitter orbit could not approach the low Earth orbit, low energy cost transfer between the low Earth orbit and the Earth pole-sitter orbit is designed using the manifold-like method and Hohmann transfer technique. In addition, station-keeping control of Earth pole-sitter orbit is obtained based on the active disturbance rejection control technique.