Optimal rendezvous and docking simulator for elliptical orbits

This paper describes the development and implementation of a simulation environment for spacecraft rendezvous and docking guidance, navigation, and control in elliptical orbits. The rendezvous and docking simulator functions in two phases. In the first phase, optimal trajectories are obtained for the point mass model of the docking vehicle subject to path constraints, with the assumption that the target vehicle is in a known elliptical orbit. In the second phase of the simulation, the chaser vehicle is considered as a rigid body whose attitude and trajectory is controlled such that the docking port is aligned with the target vehicle at the time of docking, and the flight path closely follows the optimal trajectory. The second phase is a nonlinear simulation in which the equations of motion are integrated along with gravitational and drag perturbations. The second phase of the simulation also includes the use of sensor models and data processing techniques for state estimation. The state estimates are used in the feedback control loops for following the optimal trajectory and regulating the chaser attitude.