Terminal guidance with impact angle constraint based on a practical flight strategy

The vehicle is expected to impact the target with high precision of position and direction while all the constraints are satisfied. First an optimal control model for terminal flight dynamics is formulated and the multi-shooting method is employed to obtain numerical optimal solutions. Based on the optimal solutions, a practical flight strategy is proposed to design the terminal guidance law. The guidance law is on the basis of a proportional navigation (PN) form and the resulting PN parameters are seriously selected to mimic the proposed flight strategy. To enhance the guidance performance, an on-line correction algorithm of guidance parameters is devised to eliminate the adverse effect caused by the lag-free assumption and a critical parameter for entry strategy is designed to guarantee the trajectory convergence. Simulation results show that a high precision terminal impact can be achieved and the trajectory is consistent with the optimization results.