Constructive Non-Linear Control Design With Applications to Quad-Rotor and Fixed-Wing Aircraft

This paper recalls a non-linear constructive method, based on controlling cascades of conic-systems as it applies to the control of quad-rotor aircraft. Such a method relied on the physical model of the system to construct highperformance, modest sampling period (Ts = .02 s) and lowcomplexity digital-controllers. The control of fixed-wing aircraft, however is not nearly a straight forward task in extending results related to the control of quad-rotor aircraft. Although fixed-wing aircraft and quad-rotor aircraft ultimately share the same kinematic equations of motion, fixed-wing aircraft are intimately dependent on their relationship to the wind reference frame. This additional coupling leads to additional equations of motion including those related to the angle-ofattack, slide-slip-angle, and bank angle. As a result a more advanced non-linear control method known as back-stepping is required to compensate for non-passive non-linearity’s. These back-stepping controllers are recursive in nature and can even address actuator magnitude and rate limitations and even include adaptability to unknown lift and drag coefficients. This paper presents a non-adaptive back-stepping controller which is aimed to verify a fixed-wing aircraft model not subject to actuator limitations (in order to simplify discussion). The backstepping controller proposed is less complex then previously proposed controllers, exhibits similar response characteristics while being robust to both steady head wind shear and discretetime wind gust disturbances.