The tail-sitter Vertical Takeoff and Landing(VTOL)Unmanned Aerial Vehicle(UAV),flying in a fixed-wing model,overcomes many shortcomings of traditional fixed-wing UAVs,and inherits the advantage of high overall efficiency,which means it has great development potential and very broad application prospects.The attitude of tail-sitter VTOL UAV shows a wide change range in its takeoff and landing stages,and when the attitude sensor changes more than 90 degrees in pitch direction,the Euler angles converted by the...