Soft landing on a planet: a trajectory planning approach for the Liouvillian model

A feedback regulation scheme, based on an off-line trajectory planning, is proposed for the terminal descent trajectory of a vertically controlled spacecraft attempting a soft landing maneuver on the surface of a planet with no atmosphere. The approach is based on the “Liouvillian”, character of the system, i.e., it has a defect regarding the flatness property of the spacecraft mass variable. This fact allows off-line trajectory planning controlled by a linear, time-varying, state feedback regulator complementing an ideal (nominal) open loop controller. Simulation results demonstrating the robustness of the approach are presented