Design And Experimental Verification Of Flapping Wing Aircraft Based On "Flapping-Twist-Swing" Cooperative Movement

"Flapping-twist-swing" is an important movement feature of large and medium-sized birds flying,especially during the landing stage.Aiming at this phenomenon,this paper designs a flapping wing mechanism based on a single drive to achieve the flapping-twist-swing movement of the wings.The flapping wing mechanism uses only one rotational drive and actively coordinates the flapping-twist-swing of the wing through the flapping wing transmission mechanism.This input-output mechanism and output coordination mechanism are based on the spatial six-bar flapping wing mechanism of the RRSS-SSR motion pair.Research contents include:Taking the representative of large and medium-sized flying birds such as seagulls and pigeons as bionic objects,their wing structure,flight characteristics and flight forces at various stages were analyzed.The relationship between large and medium-sized birds flight parameters and their body parameters was summarized and designed for the flapping wing mechanism,and provided an index benchmark for experimental prototype design.The biological inspiration of the flapping wing mechanism design was introduced,the flapping wing mechanism design,the establishment of the equation of motion and simulation verification were carried out,and the consistency of the output degree parameters of the flapping wing mechanism and the kinematics data of the pigeon wings was verified.In order to simplify the manufacture of the experimental prototype,the flapping wing mechanism was engineered,an engineering design scheme was given,the sensitivity analysis of the parameters was carried out,and the flapping trajectory after parameter adjustment was explored.In order to test the performance of the flapping wing mechanism,an experimental prototype based on the flapping wing mechanism was designed and produced.Including the design and selection of the driving source,the physical design of the flapping wing transmission mechanism,the design of the wing,the design of the tail and the selection of communication equipment.The 3D model of the aircraft with 0.9 m wing span was established,and the assembly and motion tests of the experimental prototype were carried out.The tests showed that it achieved the flapping-twist-swing coordinated motion characteristics.Force measurement and motion tracking experiment system was built,and the structural,motion and aerodynamic of prototype were experimentally studied.A comparison among the experimental data,theoretical model calculations,and ADAMS simulation revealed that the relative error of the flapping amplitude was 12.5%owing to the elastic deformation of the bar,and the relative error of the modified twist amplitude was 2.3%.A comparison between the inertial force generated under the condition of no airflow and no wing patagium and the theoretical calculation results indicated that the amplitude of the inertial force was consistent,maximum relative error of the upper beat was 5.9%,and maximum error of the down beat was 6.7%.According to the experimental data,the amplitude of the inertial force with wing patagium was approximately 2.2 N,maximum positive lift was 2.1 N,and maximum negative lift was-1.5 N.According to the dimensional problems,material problems and connection methods found in the prototype experiment,the 2rd flight prototype was designed and manufactured,which simplifies the connecting rod that is not firmly connected in the high-speed operation environment.The minimum size of the standard parts has redesigned the overall size of the 2rd prototype.The wing membrane is made of lighter and stronger materials.The 2rd prototype with a final weight of 350g and a wing span of lm has been developed and completed.Performed a motion test,flapping angle-23.5°-32°,twist angle 14°-46°,swing angle-12°-30°,the maximum flapping frequency can reach 5Hz,the radial reduced size of the main wing bar leads to a pronounced folding elastic deformation of the wings.These results provide a new research reference for the design of bionic flapping wing mechanisms and have application value for the short landing flight of flapping wing aircraft.