Research On Whole Envelop Control Law Design Technology For Automatic Takeoff And Landing UAV

The whole flight of a automatic takeoff and landing UAV includes three stages which areautomatic take-off, cruising and automatic landing. Thus the control law must have enough precisionand robustness in order to ensure the UAV can carry out a safety takeoff, complete the flight missionand land on the runway safely and exactly. In this paper, the full envelope control problems of aautomatic takeoff and landing UAV were studied.The correct UAV model is the foundation of control system design. In this paper, the idea ofmodular modeling was applied to establish the mathematical model of UAV. CMEX model improvesthe efficiency of digital simulation significantly. Then characteristics analysis was made which canprovide the reference for control law design.Automatic take-off section used integral of the pitch angle to restrain the effect of the disturbancemoment. Reasonable control parameters were choosed to ensure the vehicle can take off safely underthe uncertainty of aerodynamic, quality, initial conditions and efficiency of control suface.In the air flight segment, vertical and horizontal controllers were designed. In order to meet therequirements of the whole flight envelope, speed control law was added. The flight functions in theflight envelope of the UAV achieved by detailed designing the implementations of the basic flightmodes.In the automatic landing section, appropriate control strategies were selected according to therequirements of different landing periods and features of the vehicle. On that basis, the glide paths ofdescending and flare phases were designed. The precision of height control and lateral track controlwere improved to make sure that the UAV can land on the predetermined point exactly.Finally, in order to test the control performance of the whole envelope, the whole process flightsimulation was carried out in the Matlab nonlinear simulation environment. The simulation data ofthree stages was analysised detailedly. The results showed that control laws can make the UAV takeoff and landing safely and meet the flight requirements of the full envelope.