Research On Navigation And Robust Control Of Fixed-wing UAV In Complex Wind Environment During Terminal Section Of Recovery

Compared to rotor-type(multi-rotor,helicopter)drones,the fixed-wing UAVs have a longer flying range and can carry more payload.Therefore,fixed-wing UAVs have been widely used in many fields.But the main problem is that the landing of fixed-wing UAVs traditionally require a fixed runway compared to rotaplanes.Alternatively,buffering landing recovery methods such as parachute recovery and airbag buffering recovery have been already used,but the actual effect of this kind of recovery method is not good.At present,due to the limitations of the fixed-wing UAVs’ landing environment described above,their application scenario is less flexible.Once the restrictions on theri take-off and landing environment have been lifted,their application prospects will be further expanded.Therefore,for fixed-wing UAVs,the development of high-precision and high-efficiency recovery methods for landing is particularly important,and this has become one of the hottest research directions in the UAVs’ technology field at home and abroad.In view of the landing recovery application scenario of the fixed-wing UAVs,this paper first proposes two overall design methods for mechanical structure: singleline backplane hookage recovery system and line-net hybrid backplane hookage recovery system.These two schemes are applicable to the recovery of small fixedwing UAVs and the recovery of mid or large fixed-wing UAVs.Obviously,both of these line-collision recovery schemes put forward high requirements for highprecision navigation and control systems,and UAVs’ various flight parameters while being disturbed by complex wind should keep stable.Aiming at the high-precision requirements of fixed-wing recovery navigation,this paper proposes a method of providing UAVs flight position information through monocular visual navigation.While observing the position and attitude information to the specific coordinate system,which have been already known,by the camera,the picture taken by the camera will be converted by the mathematical model and solved by the positioning algorithm to obtain the position information of the UAVs,which is relative to the coordinate system.At the same time,this paper gives an analysis of the error of this positioning algorithm in a typical application scenario.In order to meet the requirements of the control system for the recovery and navigation of the fixed wing UAVs,this paper first completed the establishment and simulation of the complex wind field model.At the same time,the establishment of the UAVs’ flight dynamics model and the computation of the forces and moments encountered during the flight were completed.According to the dynamic equation of small disturbances,the design and analysis of the longitudinal flight controller and the lateral flight controller are completed based on the state feedback H∞ optimal control method.Finally,this paper combines the mathematics model of each part above,and carries on the integral mathematics simulation experiment.The paper has preliminarily verified that,in the complex wind environment,the fixed wing UAVs recovery during the final stage by the monocular visual navigation and the robust control may satisfy the accuracy requirements of line-collision recovery for the terminal section UAVs’ recovery.