Tentacle-based guidance for entry flight with no-fly zone constraint

A tentacle-based guidance method has been proposed for entry flights with the no-fly zone constraint. The proposed method is applicable to zones in general shapes. Simulations have been conducted for four entry missions with various no-fly zones. Results show that the tentacle is capable of suggesting a feasible path for the vehicle. The lateral guidance logic, which combines the tentacle feedback and the heading error, is able to fly the vehicle to the target without entering the no-fly zones. The longitudinal tracking law performs well in following the reference trajectory. Therefore, the proposed guidance method can satisfy both the conventional constraints and the additional no-fly zone constraint. Moreover, the guidance method is demonstrated to be effective when the detection of the threat is delayed, which means that it does not rely on the prior knowledge of no-fly zones. To guarantee the computational performance for guidance commands, the guidance method generates only two tentacles in each lateral guidance cycle.