Online trajectory planning and guidance for reusable launch vehicles in the terminal area

• The lateral guidance strategy is based on a new ground track geometry.
• The vertical profile is determined by an adjustable dynamic pressure profile.
• A feasible path can be rapidly generated online from the current state.
• The guidance scheme is proved to be effective by a variety of numerical trials.

A guidance scheme has been proposed based on a new online trajectory planning algorithm for an unpowered reusable launch vehicle (RLV) in the terminal area energy management (TAEM) phase. The trajectory planning algorithm is able to rapidly generate a feasible path from the current state to a desired state at approach and landing interface (ALI) based on the dynamic pressure profile and new ground track geometry. Simple guidance laws are used to keep the RLV flying along the reference path which can be adjusted online by five related parameters. Then, the effectiveness and adaptability of the proposed TAEM guidance scheme is demonstrated by numerical trials with variations in the initial energy, position and aerodynamic performance.