All-Aspect Guidance With Impact Angle Constraint Against Unknown Target Maneuver

This paper presents an all-aspect guidance law that allows the missile to achieve the interception of a target at the prescribed impact angle for any initial conditions. The proposed guidance law is designed to intercept a maneuvering target without requiring information of the normal acceleration of the target. In order to develop a guidance law that ensures all-aspect capability, the kinematic conditions that always guarantee the interception of the maneuvering target at the desired impact angle are defined. The defined kinematic conditions are expressed as two error variables for simultaneously satisfying the homing and impact angle control, and the guidance law is derived by stabilizing both error variables near zero based on the backstepping control technique. The analysis of the overall closed-loop dynamics verifies that the proposed law achieves the interception of the maneuvering target at the prescribed impact angle from any initial heading and boresight conditions, despite the absence of the information of the target acceleration. Numerical simulations also demonstrate that the proposed law achieves an acceptable miss distance at the desired impact angle for various initial conditions against different types of nonstationary targets: nonmaneuvering targets, constant-maneuvering targets, and weaving targets.