Virtual Terminal-Based Adaptive Predictor-Corrector Entry Guidance

An adaptive predictor-corrector guidance algorithm is presented to improve the performance of atmospheric entry guidance. In the predictor, a virtual entry terminal (VET) is employed instead of an actual terminal to reduce the computational request. The VET is adaptively selected from a reference trajectory according to the vehicle's authority to cancel disturbances; thus, it is reachable by the vehicle in different cases. In the corrector, an effective modification method for the bank angle and the angle of attack is designed. With the predictor-corrector algorithm, the vehicle is able to reach the VET. After the VET, a reference trajectory tracking law is employed to fly the vehicle to the actual entry terminal. The adaptive entry guidance method is verified using Monte Carlo simulations. A comparison with the conventional predictor-corrector algorithm shows that the computation time is significantly reduced by employing the VET in the adaptive algorithm.