Entry trajectory planning based on three-dimensional acceleration profile guidance

A new entry trajectory generation approach based on rapid planning three-dimensional acceleration profile (TDAP) is proposed in this paper. The TDAP planner concept means extending the traditional drag planning approach into three dimensional drag space to accommodate much larger downrange or cross-range, and improve the maneuvering capability by utilizing both angle of attack and bank as primary control commands. To figure out this problem, firstly, the planner transforms the generation of TDAP into scheming two sub-profiles, longitudinal drag acceleration profile and lateral lift to drag acceleration profile in parallel. Each profile is generated in the corridor converted by all path constraints correspondingly. Secondly, a reduced order dynamics system is employed to extract all standard state variables and adjust the three-dimensional acceleration profile, ensuring the terminal position precision requirement to be met. Finally, a combined proportional derivative (PD) feedback law is designed to track the reference profile. Simulations with the Common Aero Vehicle (CAV) model show that the 3-D trajectories of both planned and generated by the guidance law can successfully satisfy all path constraints and flight task requirements.