Stabilizing multiple sliding surface control of quad-rotor rotorcraft

The interest into the unmanned aerial vehicles (UAVs) has largely increased recently. With the advances in technologies it has become possible to test efficiently and cost-effectively different autonomous flight control concepts using small-scale aircrafts. In this paper the stabilizing control problem of quad-rotor rotorcraft using multiple sliding surface (MSS) controllers has been investigated. The ability of the MSS control approach to stabilize under-actuated systems and to deal with existing nonlinear mismatched uncertainties in the dynamic model makes it a suitable choice for controlling roll and pitch angles of the rotorcraft. The proposed method is based on the definition of multiple switching surfaces that define certain relationships between variables to be maintained after the system passes into a sliding mode. Its effectiveness on the stabilizing control of the rotorcraft is demonstrated by the results obtained from flight simulations with an accurate dynamic model of the Draganflyer V Ti four-rotor miniature helicopter.