IN recent years,unmanned aerial vehicles(UAVs)have been widely employed in different applications,both military and civilian.Especially,a fast growing civil UAV market is predicted over the next decades.However,most currently developed UAVs depend on simple control strategy.They require exact modeling of the UAVs dynamics and are vulnerable to external disturbance.Therefore,there is great need In recent years, unmanned aerial vehicles (UAVs) have been widely employed in different applications, both military and civilian .Especially, a fast growing civil UAV market is predicted over the next decades. However, most currently developed UAVs depend on simple control strategy. They require exact modeling of the UAVs dynamics and are vulnerable to external disturbance.Therefore, there is great need