Three-dimensional low-order finite-time integrated guidance and control design with side-window constraint

The infrared seeker has usually been mounted to the side of the hypersonic vehicle's head to reduce the performance degradation caused by the severe aerodynamic heating. In this way, the rotational dynamics of the flight vehicle and the line-of-sight (LOS) need to satisfy a particular constraint so that the target can be located in the seeker's field-of-view (FOV) during the whole engagement. Consequently, the coupling between the centroid dynamic and the rotational dynamic is more significant. To deal with the side-window constraint and the aforementioned significant coupling, the novel vehicle-target relative motion model in the body-LOS coordinate system is introduced to describe the guidance problem accurately. Combined with the dynamics of body angular rates and the fact that the derivative of angular rates appears in the proposed relative motion model, a novel three-dimensional (3D) low-order integrated guidance and control (IGC) design model is obtained. Furthermore, the IGC design with a side-window constraint can be converted to an output constraint problem of a low-order nonlinear system. Meanwhile, the desired reference trajectories of the FOV angles are designed to meet the asymmetric FOV constraint and the terminal accuracy requirement, simultaneously. Based on the asymmetric barrier Lyapunov function (BLF), finite-time stability theory and the modified dynamic surface technique, a novel 3D low-order adaptive finite-time IGC scheme with side-window constraint is proposed in this paper. The finite-time stability of the closed-loop system is proven, and the side-window constraint would never be violated using Lyapunov theory. Finally, the effectiveness and robustness of the newly proposed IGC algorithm are demonstrated by means of numerical simulations.