A Guidance Law Based on Correcting Velocity Direction Continuously in Finite Time

Abstract

Taking the limited control authority and guidance information of a gun-launched guided projectile into account, a novel three-dimensional terminal guidance law based on the combination of the correction of the velocity direction via impact point prediction and continuous distribution of acceleration command is proposed. The deviations between the impact point of the projectile and the target are predicted based on the series solutions of the nonlinear ballistic equations. According to the deviations, a nonlinear method to calculate the direction angles corrections of the current speed is addressed. Design the remaining flight time as the correction time. The acceleration correction formulas are established through sharing the direction angles corrections of the current speed into the whole remaining guided flight to reduce the possibility of command saturation. By predicting the impact point and distributing acceleration corrections continuously to shape the trajectory in real time. The simulation results show that the proposed guidance law is feasible and effective, and provides the performances of higher precision and less requirements of control authority and greater damage effects on account of the larger impact angle, compared with the proportional navigation law, which provides a reference for the application of the guided projectile.