Proportional Navigation Guidance With Virtual Targeting for Impact Angle Control

This article introduces an impact-angle-control guidance (IACG) method employing the concept of a virtual target. The proposed guidance law is structured as a proportional navigation guidance (PNG) command, directed toward intercepting this virtual target. Initially, we delve into the characteristics of the PNG law, leveraging them to devise the proposed IACG law. By harnessing PNG's traits, we analytically determine the desired position of the virtual target, ensuring adherence to boundary conditions. Consequently, the proposed method can intercept the true target with the desired impact direction while leveraging PNG's simplicity and obviating the need for time-to-go estimation, unlike existing approaches. Furthermore, it is adaptable to nonlinear engagement scenarios featuring speed variations. We thoroughly examine the properties of the virtual target position under various engagement conditions and investigate the link between the proposed approach and the optimal guidance laws. Notably, the performance index of the proposed IACG is closely tied to control energy minimization, due to PNG's characteristics. Finally, through numerical simulations and comparisons, we showcase the validation and effectiveness of the proposed IACG approach.