Research on Nonlinear Guidance Law Design for UAV-to-Ground Attack Under Field-of-View Constraint

This paper addresses the guidance law design problem for unmanned aerial vehicles (UAVs) to attack ground targets by presenting the three-dimensional relative motion equations between small quadrotor UAV and targets as a multi-variable nonlinear system subject to uncertainties, a sliding-mode-based control approach is proposed to deal with the uncertain multi-variable nonlinear systems. Moreover, due to the limitations of size and weight, small UAVs only carry strapdown seekers in this study, which would cause field-of-view (FOV) constraint. To overcome this constraint, the field-of-view of the strapdown seeker is transformed into an asymmetric constraint on relative motion variables, and the tangent-type barrier Lyapunov function (Tan-BLF) is employed to deal with the asymmetric constraint. Then, applying Lyapunov stability theory, an adaptive law is constructed to compensate for the disturbance caused by the target maneuver. In conclusion, a nonlinear adaptive sliding-mode guidance law is proposed such that non-cooperative maneuvering targets could be attacked accurately only with relative information regarding targets while satisfying line-of-sight constraints.