Singular Perturbation Control of the Lateral-Directional Flight Dynamics of an UAV

This paper presents a singular perturbation control strategy for regulating the lateral-directional flight dynamics of an Unmanned Air Vehicle (UAV). The proposed control strategy is based on a four-time-scale (4TS) decomposition that includes the side-slip velocity, bank angle, yaw rate and roll rate dynamics, with the control signals being the aileron and rudder deflection. The nonlinear control strategy drives the system to follow a reference in load factor which in return provides references in bank angle, side-slip velocity and yaw rate. In addition, the control strategy permits to select the desired dynamics for all the singularly perturbed subsystems. Numerical results are included for a realistic nonlinear UAV model, including saturation on the control signals, and unmodeled dynamics.