Sprial Motion Control Of UAV Under The Runnder Limited Deadlock

The advantages of Unmanned Aerial Vehicles (UAV) are increasingly recognized in the military and civilian aspects. Because more and more UAV are used, the number of accidents is gradually increasing, and the rudder deadlocking is one of many faults. When the rudder deadlocking happens and the longitudinal stability is bigger than the lateral stability, the UAV can easily step into the spiral motion. As the spiral motion is the early stage of the spin motion, if we do not take control of it, once it step into the spin motion, the whole UAV will crash in the end.In this paper, the problem that the UAV stepping into spiral motion under the rudder deadlocking is studied. First of all, by analyzing the force and moment that the deadlock rudder produced and combining the physical of the spiral motion, the conclusion that the UAV will step into the spiral motion when the rudder deadlock happens and under a certain condition is got. According to the normal model of UAV, then the force and moment of the deadlock rudder are regarded as constant disturbance, the models of differential horizontal tail UAV and flying head tail UAV which are related to the spiral motion are established respectively. According to the models, we obtain the elevator angle of other surfaces which can compensate the effect of the dead rudder by theory analysis. The method based on determining the angle of the fault rudder is proposed according to the limited controlling range of the other control surfaces. The correctness and validity of the method is verified by the example analysis.On the foundation of these analyzes, the design of control law is studied emphatically. When the rudder is the uncontrollable surface, a method which designs the aileron channel control law only is proposed to make the UAV step out the spiral motion. Based on the control law of the normal UAV, the classical PID control method and the characteristic structure configuration method which can make the UAV step out the spiral motion is respectively used to design the control law. The validity of the designed control law is verified by the simulation experiments. In the end, the design and realization of the UAV spiral motion controlling software package which is based on the VC++ and Matlab are proposed.