Time-to-go Estimator for Missiles Guided by BPNG

Biased proportional navigation guidance (BPNG) law is widely used for missiles to home on the target with the required incidence angle. Nowadays the BPNG law has received great interest for sea skimming anti-ship missile (ASM) littoral operation applications. In this paper, we propose a new time-to-go estimator for sea skimming ASMs guided by the horizontal BPNG law. A BPNG problem is formulated in a simple linearized homing geometry and the solution trajectory is introduced. The length of the BPNG trajectory is approximated based on the solution. The time-to-go estimator is derived by applying the Kalman filter theory to the approximated length. Simulation results show that the proposed estimator can estimate the time-to-go very effectively with small computational load.