Design of landing trajectory and safe interface area for RLV with initial interface errors

The trajectory planning for reusable launch vehicle (RLV) approach and landing with initial interface error is researched. The automatic approach and landing trajectory is divided into three sections: interface section, nominal glideslope section and nominal flare section. The last two sections are designed firstly, based on the nominal interface states and the desire touch down states. Then, an online three dimensional trajectory generation method for interface section by which the vertical, horizontal and velocity errors are concerned simultaneously is raised, together with a piecewise linear speed brake adjustment strategy. According to the Interface trajectory, the concept of “safe interface area (SIA)” in the Interface height plane is proposed and the method is also included. Finally, the simulations show the reference value of the SIA and trajectory generation method for the trajectory planning of unpowered vehicle approach and landing with initial interface errors.