Asymptotically Decoupled Variable Structure Control of Systems and Large Maneuver of Aircraft

This paper treats the question of control of a class of nonlinear systems which can be decoupled by state variable feedback. Based on variable structure system (VSS) theory, a discontinuous control law is derived which accomplishes asymptotic decoupled output trajectory following in the presence of uncertainty in the system. In the closed-loop system, the trajectories are attracted towards a chosen hypersurface in the state space and then slide along it. During the "sliding phase" the motion is insensitive to parameter variations. Based on this result, a control law for asymptotically decoupled control of roll angle, angle of attack and sideslip in rapid, nonlinear maneuvers is derived. Simulation results are presented to show that large, simultaneous lateral and longitudinal maneuvers can be performed in spite of uncertainty in the stability derivatives.