Design of higher order sliding mode control laws for a multi modal agile maneuvering UCAV

In this work, we consider the design of a nonlinear control system for an unmanned combat air vehicle for executing agile maneuvers over the full flight envelope. From the inspection of well known smooth aerobatic and combat maneuvers, we see that complex maneuvers can be decomposed into a specific set of different sub maneuvers to cover any arbitrary flight maneuver. To control each sub mode an inner/outer control loop approach with higher order sliding mode controllers are developed. These controllers attain robust tracking of maneuver profiles for nonlinear aircraft dynamics. Resulting algorithms are applied to a high fidelity six degrees of freedom F-16 fighter aircraft model. We show that final design is capable of autonomously tracking the reference trajectories in the presence of unmodeled dynamics, disturbances and nonminimum phase outputs.