Lateral Entry Guidance with Terminal Time Constraint

A simultaneous attack mission requires the entry vehicle to be capable of controlling the terminal time. To satisfy the terminal time constraint and meanwhile to cooperate with the previous longitudinal guidance algorithms, a lateral entry guidance method is developed using a closed-loop trajectory predictor for the terminal time, a bank reversal logic based on a double-corridor strategy, and a terminal time determination approach. The double-corridor contains a time error corridor used to activate the modification of the terminal time, and an adjustable heading corridor, when activated, used to reduce the terminal time error. The desired terminal time is calculated according to a feasibility index which describes the tolerance of aerodynamic dispersions. The simulations of a time constrained entry flight show that the lateral guidance method can achieve a high accuracy of the terminal time control while satisfying the conventional entry constraints. The advantage of the desired terminal time given by the feasibility index is also demonstrated.