Design And Research Of Long Endurance Uav Using Smart Material

Compared with traditional flight vehicles,morphing aircraft can obtain superior aerodynamic efficiency or enhanced maneuverability through morphing wings or body parts.With continuous development in new materials and technologies in recent years,many morphing aircraft configurations were proposed by researchers home and abroad.Some of the key technologies have been thoroughly studied and many experiment have been carried out for demonstration and verification,the results show that morphing technologies enhance performance of flight vehicles significantly.Nowadays,research in long endurance aircraft becomes into a hot spot due to increasing demands in longer flight duration of aircrafts,thus,foreign research institutions,large corporations,aircraft manufactures and even Internet giants begin to pour money in developing technologies for long endurance UAVs.However,long endurance UAVs have extensive requirements on aerodynamic performance and structural loads.Though morphing structure may improve aerodynamic performance of long endurance UAVs,their structural weight compromises the application.To solve these problems,based on new smart materials currently developed,some solutions are proposed both in aerodynamic performance and smart structure.A light weight morphing structure that can achieve large deformation was designed and some solutions are presented in this paper.The contents and results are show as follows:1)To reduce structural weight of morphing mechanism for long endurance UAV,a concept named Driving Skin is proposed.The Driving Skin,based on newly developed artificial muscles,integrates the skin of UAV and driving part of morphing mechanism,which significantly reduces the weight of the whole UAV.In addition,Driving Skin can effectively transfer aerodynamic loads to inner structure.2)Based on the Driving Skin,a camber morphing mechanism is developed.It can effectively drive the morphing mechanism to achieve large wing deformation,and still ensure the smoothness of the skin.In addition,not like other camber morphing mechanisms that are resisted by aerodynamic loads in large deformation,which in turn results in demands on high strength and larger structural weight,the aerodynamic loads in this morphing mechanism can be used as partial driving force,thus the requirement on driving force for this mechanism can be reduced,therefore,large deformation with light structure can be achieved.3)A “Sandwich Skin” concept is proposed to achieve large thickness deformation.It can effectively transfer aerodynamic loads from skin to internal structure and achieve a variation in more than 10% in relative thickness.In addition,the driving mechanism can be simplified in this design,easy for practical application.4)An experiment for function simulation is proposed in this paper,to demonstrate the feasibility and effectiveness of this design,the results show that the camber morphing of this design is applicable and controllable.A wing box is manufactured to demonstrate the practical application of this design.5)A special airfoil design tool is developed based on swarm particle optimization algorithm,to customize airfoils used in the design of long endurance UAV.Endurance factor,which can be used to present the capability of endurance of UAV,is adopted to design some airfoils to verify this tool.6)A long endurance UAV with flapless morphing wing is designed.The airfoil used is design by the tool developed.Compared with the UAV using SD7037 airfoil,the one using designed airfoil achieves a 50% and 20% improvement in L/D of two dimensional airfoil and endurance factor of the whole UAV,respectively.7)The pitching and rolling performance of the UAV with flapless wing is studied.The results show that the design can effectively change the pitching and rolling momentums,thus control the UAV.In the future,it may possible to get rid of the control surfaces,thus significantly reduce drag and improve the endurance of UAVs.8)The Active Disturbance Rejection Control(ADRC)method is adopted to design the attitude control law for long endurance morphing wing UAV in this paper,providing a solution for this problem.The simulation results show that the control law designed is effective and efficient in controlling the attitude of the UAV designed.