Impact Time and Angle Control Guidance

Abstract

In this paper, a guidance strategy, which extends the existing impact angle control guidance laws to cater to the impact time constraints as well, is proposed. This guidance scheme is based on switching between sliding mode control based impact time control guidance law and the impact angle control guidance laws. Unlike the usual impact time guidance laws, the proposed guidance law also takes into account the requirement of the curvature of the trajectory toward the interception point due to the an impact angle requirement. The impact time guidance law is derived using a switching surface based on nonlinear engagement dynamics and time-to-go. In the first step, the guidance law corrects for the impact time and then in the second step, the impact angle control guidance achieves the impact angle requirements along with the interception. Initially stationary targets are considered, and later the same guidance scheme is extended to a constant velocity target using the notion of predicted interception. Numerical simulation results are presented to validate the proposed guidance law for different initial engagement geometries, impact times, and angles scenarios. By controlling both the impact time and angle, simulation results are presented to evaluate the performance for different salvo attack scenarios.