A theoretical modeling approach as well as an unsteady analytical method is used to study aerodynamic characteristics of wing flapping with asymmetric stroke-cycles in connection with an oblique stroke plane during in...A theoretical modeling approach as well as an unsteady analytical method is used to study aerodynamic characteristics of wing flapping with asymmetric stroke-cycles in connection with an oblique stroke plane during insect forward flight. It is revealed that the aerodynamic asymmetry between the downstroke and the upstroke due to stroke-asymmetrical flapping is a key to understand the flow physics of generation and modulation of the lift and the thrust. Predicted results for examples of given kinematics validate more specifically some viewpoints that the wing lift is more easily produced when the forward speed is higher and the thrust is harder, and the lift and the thrust are generated mainly during downstroke and upstroke, respectively. The effects of three controlling parameters, i.e. the angles of tilted stroke plane, the different downstroke duration ratios, and the different angles of attack in both down- and up-stroke, are further discussed. It is found that larger oblique angles of stroke planes generate larger thrust but smaller lift; larger downstroke duration ratios lead to larger thrust, while making little change in lift and input aerodynamic power; and again, a small increase of the angle of attack in downstroke or upstroke may cause remarkable changes in aerodynamic performance in the relevant stroke.展开更多
This paper is based on a previously developed bio-inspired Flapping Wing Aerial Vehicle(FWAV),RoboFalcon,which can fly with a morphing-coupled flapping pattern.In this paper,a simple flapping stroke control system bas...This paper is based on a previously developed bio-inspired Flapping Wing Aerial Vehicle(FWAV),RoboFalcon,which can fly with a morphing-coupled flapping pattern.In this paper,a simple flapping stroke control system based on Hall effect sensors is designed and applied,which is capable of assigning different up-and down-stroke speeds for the RoboFalcon platform to achieve an adjustable downstroke ratio.The aerodynamic and power characteristics of the morphing-coupled flapping pattern and the conventional flapping pattern with varying downstroke ratios are measured through a wind tunnel experiment,and the corresponding aerodynamic models are developed and analyzed by the nonlinear least squares method.The relatively low power consumption of the slow-downstroke mode of this vehicle is verified through outdoor flight tests.The results of wind tunnel experiments and flight tests indicate that increased downstroke duration can improve aerodynamic and power performance for the RoboFalcon platform.展开更多
A generic approach to model the kinematics and aerodynamics of flapping wing ornithopter has been followed, to model and analyze a flapping bi- and quad-wing ornithopter and to mimic flapping wing biosystems to produc...A generic approach to model the kinematics and aerodynamics of flapping wing ornithopter has been followed, to model and analyze a flapping bi- and quad-wing ornithopter and to mimic flapping wing biosystems to produce lift and thrust for hovering and forward flight. Considerations are given to the motion of a rigid and thin bi-wing and quad-wing ornithopter in flapping and pitching motion with phase lag. Basic Unsteady Aerodynamic Approach incorporating salient features of viscous effect and leading-edge suction are utilized. Parametric study is carried out to reveal the aerodynamic characteristics of flapping bi- and quad-wing ornithopter flight characteristics and for comparative analysis with various selected simple models in the literature, in an effort to develop a flapping bi- and quad-wing ornithopter models. In spite of their simplicity, results obtained for both models are able to reveal the mechanism of lift and thrust, and compare well with other work.展开更多
This paper presents a novel modelling method to study the thrust generation mechanism of biplane flapping wings made of thin and highly deformable membrane.Based on the principle of strain energy equivalence,the membr...This paper presents a novel modelling method to study the thrust generation mechanism of biplane flapping wings made of thin and highly deformable membrane.Based on the principle of strain energy equivalence,the membrane structures were modelled by mass-spring systems.The aerodynamic loads were calculated by a simplified quasi-steady aerodynamic model with consideration of the clap-and-fling mechanism.The impact force was introduced into the system when two wing surfaces were in contact.For wing-dynamics simulation problems,convergence analyses were conducted to obtain suitable mesh resolution.To validate the present modelling method,the predicted thrust and required power of a biplane flapping-wing air vehicle were compared with the experimental data.The effect of the forward speed was also analyzed in this paper.It was shown that as the forward speed increases the thrust production efficiency becomes lower together with smaller wing deformation.展开更多
Modeling the dynamics of flapping wing aerial vehicle is challenging due to the complexity of aerodynamic effects and mechanical structures.The aim of this work is to develop an accurate dynamics model of flapping win...Modeling the dynamics of flapping wing aerial vehicle is challenging due to the complexity of aerodynamic effects and mechanical structures.The aim of this work is to develop an accurate dynamics model of flapping wing aerial vehicle based on real flight data.We propose a modeling framework that combines rigid body dynamics with a neural network to predict aerodynamic effects.By incorporating the concept of flapping phase,we significantly enhance the network’s ability to analyze transient aerodynamic behavior.We design and utilize a phase-functioned neural network structure for aerodynamic predictions and train the network using real flight data.Evaluation results show that the network can predict aerodynamic effects and demonstrate clear physical significance.We verify that the framework can be used for dynamic propagation and is expected to be utilized for building simulators for flapping wing aerial vehicles.展开更多
Flapping-Wing Micro Air Vehicles(FMAVs)are compact and agile,capable of accessing narrow spaces that conventional vehicles struggle to reach,such as ruins,caves,or the interiors of complex structures,making them ideal...Flapping-Wing Micro Air Vehicles(FMAVs)are compact and agile,capable of accessing narrow spaces that conventional vehicles struggle to reach,such as ruins,caves,or the interiors of complex structures,making them ideal tools for reconnaissance and rescue missions.1 However,the operation of FMAVs relies on coordinating multiple forces with different scaling effects,posing challenges to miniaturization design.展开更多
Throughout the previous studies,none of them are involved in analysing the downwash flow effect on the control surface of the Flapping Wing Rotor(FWR).An overset CFD numerical model is built up and validated to study ...Throughout the previous studies,none of them are involved in analysing the downwash flow effect on the control surface of the Flapping Wing Rotor(FWR).An overset CFD numerical model is built up and validated to study the downwash flow’s effect on the stability of the FWR.After simulation,a cone like self-lock region which acts as the critical condition determining the stability of FWR is found.Only when the flow’s resultant velocity acting on the control surface lies in the stable region,the FWR can keep stable.The size of the cone like self-lock stable region can be enlarged by increasing the maximum feasible deflection angle constrained by mechanical design or enhancing the equivalent downwash flow velocity.Among all the simulated cases,when J=2.67(f=5 Hz,■=5 r/s),the largest average equivalent downwash flow velocities are found.On the other hand,the recovery torque could be enhanced due to the increase of the arm of the lateral force.According to these simulation results,a 43 g FWR model with two control surfaces and two stabilizers is then designed.A series of flight tests is then conducted to help confirm the conclusion of the mechanism research in this work.Overall,this study points out several strategies to increase the flight stability of the FWR and finally realizes the stable climb flight and mild descent flight of the FWR.展开更多
The application of biomimetics in the development of unmanned-aerial-vehicles （UAV） has advanced to an exceptionally small scale of nano-aerial-vehicles （NAV）, which has surpassed its immediate predecessor of micr...The application of biomimetics in the development of unmanned-aerial-vehicles （UAV） has advanced to an exceptionally small scale of nano-aerial-vehicles （NAV）, which has surpassed its immediate predecessor of micro-aerial-vehicles （MAV）, leaving a vast range of development possi- bilities that MAVs have to offer. Because of the prompt advancement into the NAV research devel- opment, the true potential and challenges presented by MAV development were never solved, understood, and truly uncovered, especially under the influence of transition and low Reynolds number flow characteristics. This paper reviews a part of previous MAV research developments which are deemed important of notification; kinematics, membranes, and flapping mechanisms ranges from small birds to big insects, which resides within the transition and low Reynolds number regimes. This paper also reviews the possibility of applying a piezoelectric transmission used to pro- duce NAV flapping wing motion and mounted on a MAV, replacing the conventional motorized flapping wing transmission. Findings suggest that limited work has been done for MAVs matching these criteria. The preferred research approach has seen bias towards numerical analysis as compared to experimental analysis.展开更多
A three-wing Flapping Wing Rotor Micro Aerial Vehicle(FWR-MAV)which can perform controlled flight is introduced and an experimental study on this vehicle is presented.A mechanically driven flapping rotary mechanism is...A three-wing Flapping Wing Rotor Micro Aerial Vehicle(FWR-MAV)which can perform controlled flight is introduced and an experimental study on this vehicle is presented.A mechanically driven flapping rotary mechanism is designed to drive the three flapping wings and generate lift,and control mechanisms are designed to control the pose of the FWR-MAV.A flight control board for attitude control with robust onboard attitude estimation and a control algorithm is also developed to perform stable hovering flight and forward flight.A series of flight tests was conducted,with hovering flight and forward flight tests performed to optimize the control parameters and assess the performance of the FWR-MAV.The hovering flight test shows the ability of the FWR-MAV to counteract the moment generated by rotary motion and maintain the attitude of the FWR-MAV in space;the experiment of forward flight shows that the FWR-MAV can track the desired attitude.展开更多
Most insects and hummingbirds can generate lift during both upstroke and downstroke with a nearly horizontal flapping stroke plane,and perform precise hovering flight.Further,most birds can utilize tails and muscles i...Most insects and hummingbirds can generate lift during both upstroke and downstroke with a nearly horizontal flapping stroke plane,and perform precise hovering flight.Further,most birds can utilize tails and muscles in wings to actively control the flight performance,while insects control their flight with muscles based on wing root along with wing’s passive deformation.Based on the above flight principles of birds and insects,Flapping Wing Micro Air Vehicles(FWMAVs)are classified as either bird-inspired or insect-inspired FWMAVs.In this review,the research achievements on mechanisms of insect-inspired,hoverable FWMAVs over the last ten years(2011-2020)are provided.We also provide the definition,function,research status and development prospect of hoverable FWMAVs.Then discuss it from three aspects:bio-inspiration,motor-driving mechanisms and intelligent actuator-driving mechanisms.Following this,research groups involved in insect-inspired,hoverable FWMAV research and their major achievements are summarized and classified in tables.Problems,trends and challenges about the mechanism are compiled and presented.Finally,this paper presents conclusions about research on mechanical structure,and the future is discussed to enable further research interests.展开更多
Flying insects are capable of flapping their wings to provide the required power and control forces for flight.A coordinated organizational system including muscles,wings,and control architecture plays a significant r...Flying insects are capable of flapping their wings to provide the required power and control forces for flight.A coordinated organizational system including muscles,wings,and control architecture plays a significant role,which provides the sources of inspiration for designing flapping-wing vehicles.In recent years,due to the development of micro-and meso-scale manufacturing technologies,advances in components technologies have directly led to a progress of smaller Flapping-Wing Nano Air Vehicles(FWNAVs)around gram and sub-gram scales,and these air vehicles have gradually acquired insect-like locomotive strategies and capabilities.This paper will present a selective review of components technologies for ultra-lightweight flapping-wing nano air vehicles under 3 g,which covers the novel propulsion methods such as artificial muscles,flight control mechanisms,and the design paradigms of the insect-inspired wings,with a special focus on the development of the driving technologies based on artificial muscles and the progress of the biomimetic wings.The challenges involved in constructing such small flapping-wing air vehicles and recommendations for several possible future directions in terms of component technology enhancements and overall vehicle performance are also discussed in this paper.This review will provide the essential guidelines and the insights for designing a flapping-wing nano air vehicle with higher performance.展开更多
The analysis of the passive rotation feature of a micro Flapping Rotary Wing（FRW）applicable for Micro Air Vehicle（MAV） design is presented in this paper. The dynamics of the wing and its influence on aerodynamic p...The analysis of the passive rotation feature of a micro Flapping Rotary Wing（FRW）applicable for Micro Air Vehicle（MAV） design is presented in this paper. The dynamics of the wing and its influence on aerodynamic performance of FRW is studied at low Reynolds number（~10~3）.The FRW is modeled as a simplified system of three rigid bodies： a rotary base with two flapping wings. The multibody dynamic theory is employed to derive the motion equations for FRW. A quasi-steady aerodynamic model is utilized for the calculation of the aerodynamic forces and moments. The dynamic motion process and the effects of the kinematics of wings on the dynamic rotational equilibrium of FWR and the aerodynamic performances are studied. The results show that the passive rotation motion of the wings is a continuous dynamic process which converges into an equilibrium rotary velocity due to the interaction between aerodynamic thrust, drag force and wing inertia. This causes a unique dynamic time-lag phenomena of lift generation for FRW, unlike the normal flapping wing flight vehicle driven by its own motor to actively rotate its wings. The analysis also shows that in order to acquire a high positive lift generation with high power efficiency and small dynamic time-lag, a relative high mid-up stroke angle within 7–15° and low mid-down stroke angle within -40° to -35° are necessary. The results provide a quantified guidance for design option of FRW together with the optimal kinematics of motion according to flight performance requirement.展开更多
Flapping-wing flight, as the distinctive flight method retained by natural flying creatures, contains profound aerodynamic principles and brings great inspirations and encouragements to drone developers. Though some i...Flapping-wing flight, as the distinctive flight method retained by natural flying creatures, contains profound aerodynamic principles and brings great inspirations and encouragements to drone developers. Though some ingenious flapping-wing robots have been designed during the past two decades, development and application of autonomous flapping-wing robots are less successful and still require further research. Here, we report the development of a servo-driven bird-like flapping-wing robot named USTBird-I and its application in autonomous airdrop.Inspired by birds, a camber structure and a dihedral angle adjustment mechanism are introduced into the airfoil design and motion control of the wings, respectively. Computational fluid dynamics simulations and actual flight tests show that this bionic design can significantly improve the gliding performance of the robot, which is beneficial to the execution of the airdrop mission.Finally, a vision-based airdrop experiment has been successfully implemented on USTBird-I, which is the first demonstration of a bird-like flapping-wing robot conducting an outdoor airdrop mission.展开更多
This paper establishes and analyzes a high-fidelity nonlinear time-periodic dynamic model and the corresponding state observer for flapping vibration suppression of a novel tailless Flapping Wing Micro Air Vehicle(FWM...This paper establishes and analyzes a high-fidelity nonlinear time-periodic dynamic model and the corresponding state observer for flapping vibration suppression of a novel tailless Flapping Wing Micro Air Vehicle(FWMAV),named NPU-Tinybird.Firstly,a complete modeling of NPU-Tinybird is determined,including the aerodynamic model based on the quasi-steady method,the kinematic and dynamic model about the mechanism of flapping and attitude control,combined with the single rigid body dynamic model.Based on this,a linearized longitudinal pitch dynamic cycle-averaged model is obtained and analyzed through the methods of neural network fitting and system identification,preparing for the design of flapping vibration suppression observer.Flapping vibration is an inherent property of the tailless FWMAV,which arises from the influence of time-periodic aerodynamic forces and moments.It can be captured by attitude and position sensors on the plane,which impairs the flight performance and efficiency of flight controller and actuators.To deal with this problem,a novel state observer for flapping vibration suppression is designed.A robust optimal controller based on the linear quadratic theory is also designed to stabilize the closed-loop system.Simulation results are given to verify the performance of the observer,including the closed loop responses combined with robust optimal controller,the comparison of different parameters of observer and the comparison with several classic methods,such as Kalman filter,H-infinity filter and low-pass filter,which prove that the novel observer owns a fairly good suppression effect on flapping vibration and benefits for the improvement of flight performance and control efficiency.展开更多
The problem of flapping motion control of Micro Air Vehicles (MAVs) with flapping wings was studied in this paper.Based upon the knowledge of skeletal and muscular components of hummingbird, a dynamic model for flappi...The problem of flapping motion control of Micro Air Vehicles (MAVs) with flapping wings was studied in this paper.Based upon the knowledge of skeletal and muscular components of hummingbird, a dynamic model for flapping wing wasdeveloped.A control scheme inspired by human memory and learning concept was constructed for wing motion control ofMAVs.The salient feature of the proposed control lies in its capabilities to improve the control performance by learning fromexperience and observation on its current and past behaviors, without the need for system dynamic information.Furthermore,the overall control scheme has a fairly simple structure and demands little online computations, making it attractive for real-timeimplementation on MAVs.Both theoretical analysis and computer simulation confirms its effectiveness.展开更多
基金The project supported by the National Natural Science Foundation of China(10072066,90305009) the Chinese Academy of Sciences(KJCX-SW-L04,KJCX2-SW-L2)
文摘A theoretical modeling approach as well as an unsteady analytical method is used to study aerodynamic characteristics of wing flapping with asymmetric stroke-cycles in connection with an oblique stroke plane during insect forward flight. It is revealed that the aerodynamic asymmetry between the downstroke and the upstroke due to stroke-asymmetrical flapping is a key to understand the flow physics of generation and modulation of the lift and the thrust. Predicted results for examples of given kinematics validate more specifically some viewpoints that the wing lift is more easily produced when the forward speed is higher and the thrust is harder, and the lift and the thrust are generated mainly during downstroke and upstroke, respectively. The effects of three controlling parameters, i.e. the angles of tilted stroke plane, the different downstroke duration ratios, and the different angles of attack in both down- and up-stroke, are further discussed. It is found that larger oblique angles of stroke planes generate larger thrust but smaller lift; larger downstroke duration ratios lead to larger thrust, while making little change in lift and input aerodynamic power; and again, a small increase of the angle of attack in downstroke or upstroke may cause remarkable changes in aerodynamic performance in the relevant stroke.
基金supported by National Natural Science Foundation of China under Grants No.52175277 and 12272318,and ND Basic Research Funds under Grants G2022WDwas supported in part by the Basic Research Program of Shenzhen under GrantJCYJ20190806142816524.
文摘This paper is based on a previously developed bio-inspired Flapping Wing Aerial Vehicle(FWAV),RoboFalcon,which can fly with a morphing-coupled flapping pattern.In this paper,a simple flapping stroke control system based on Hall effect sensors is designed and applied,which is capable of assigning different up-and down-stroke speeds for the RoboFalcon platform to achieve an adjustable downstroke ratio.The aerodynamic and power characteristics of the morphing-coupled flapping pattern and the conventional flapping pattern with varying downstroke ratios are measured through a wind tunnel experiment,and the corresponding aerodynamic models are developed and analyzed by the nonlinear least squares method.The relatively low power consumption of the slow-downstroke mode of this vehicle is verified through outdoor flight tests.The results of wind tunnel experiments and flight tests indicate that increased downstroke duration can improve aerodynamic and power performance for the RoboFalcon platform.
文摘A generic approach to model the kinematics and aerodynamics of flapping wing ornithopter has been followed, to model and analyze a flapping bi- and quad-wing ornithopter and to mimic flapping wing biosystems to produce lift and thrust for hovering and forward flight. Considerations are given to the motion of a rigid and thin bi-wing and quad-wing ornithopter in flapping and pitching motion with phase lag. Basic Unsteady Aerodynamic Approach incorporating salient features of viscous effect and leading-edge suction are utilized. Parametric study is carried out to reveal the aerodynamic characteristics of flapping bi- and quad-wing ornithopter flight characteristics and for comparative analysis with various selected simple models in the literature, in an effort to develop a flapping bi- and quad-wing ornithopter models. In spite of their simplicity, results obtained for both models are able to reveal the mechanism of lift and thrust, and compare well with other work.
基金funded by Vietnam National Foundation for Science and Technology Development(NAFOSTED)(Grant No.107.01-2021.39).
文摘This paper presents a novel modelling method to study the thrust generation mechanism of biplane flapping wings made of thin and highly deformable membrane.Based on the principle of strain energy equivalence,the membrane structures were modelled by mass-spring systems.The aerodynamic loads were calculated by a simplified quasi-steady aerodynamic model with consideration of the clap-and-fling mechanism.The impact force was introduced into the system when two wing surfaces were in contact.For wing-dynamics simulation problems,convergence analyses were conducted to obtain suitable mesh resolution.To validate the present modelling method,the predicted thrust and required power of a biplane flapping-wing air vehicle were compared with the experimental data.The effect of the forward speed was also analyzed in this paper.It was shown that as the forward speed increases the thrust production efficiency becomes lower together with smaller wing deformation.
基金supported by National Natural Science Foundation of China under Grant No.62236007the specialized research projects of Huanjiang Laboratory.
文摘Modeling the dynamics of flapping wing aerial vehicle is challenging due to the complexity of aerodynamic effects and mechanical structures.The aim of this work is to develop an accurate dynamics model of flapping wing aerial vehicle based on real flight data.We propose a modeling framework that combines rigid body dynamics with a neural network to predict aerodynamic effects.By incorporating the concept of flapping phase,we significantly enhance the network’s ability to analyze transient aerodynamic behavior.We design and utilize a phase-functioned neural network structure for aerodynamic predictions and train the network using real flight data.Evaluation results show that the network can predict aerodynamic effects and demonstrate clear physical significance.We verify that the framework can be used for dynamic propagation and is expected to be utilized for building simulators for flapping wing aerial vehicles.
基金supported by the Scientific Research Innovation Capability Support Project for Young Faculty,China(No.ZYGXQNJSKYCXNLZCXM-D1)the National Natural Science Foundation of China(No.52272384).
文摘Flapping-Wing Micro Air Vehicles(FMAVs)are compact and agile,capable of accessing narrow spaces that conventional vehicles struggle to reach,such as ruins,caves,or the interiors of complex structures,making them ideal tools for reconnaissance and rescue missions.1 However,the operation of FMAVs relies on coordinating multiple forces with different scaling effects,posing challenges to miniaturization design.
基金supported by the following funding organizations in China:National Natural Science Foundation of China(Grant No.52375116 and Grant No.52105285)the Aeronautical Science Foundation of China(Grant No.ASFC-20230023052001)+3 种基金China Postdoctoral Science Foundation(Grant No.2024M754237)National Key Research and Development Program of China(2024YFB470920001)Science and Technology Plan Project of Wenzhou Municipality(Grant No.ZG2024001)Basic Public Welfare Research Program of Wenzhou(Grant No.G2023046).
文摘Throughout the previous studies,none of them are involved in analysing the downwash flow effect on the control surface of the Flapping Wing Rotor(FWR).An overset CFD numerical model is built up and validated to study the downwash flow’s effect on the stability of the FWR.After simulation,a cone like self-lock region which acts as the critical condition determining the stability of FWR is found.Only when the flow’s resultant velocity acting on the control surface lies in the stable region,the FWR can keep stable.The size of the cone like self-lock stable region can be enlarged by increasing the maximum feasible deflection angle constrained by mechanical design or enhancing the equivalent downwash flow velocity.Among all the simulated cases,when J=2.67(f=5 Hz,■=5 r/s),the largest average equivalent downwash flow velocities are found.On the other hand,the recovery torque could be enhanced due to the increase of the arm of the lateral force.According to these simulation results,a 43 g FWR model with two control surfaces and two stabilizers is then designed.A series of flight tests is then conducted to help confirm the conclusion of the mechanism research in this work.Overall,this study points out several strategies to increase the flight stability of the FWR and finally realizes the stable climb flight and mild descent flight of the FWR.
文摘The application of biomimetics in the development of unmanned-aerial-vehicles （UAV） has advanced to an exceptionally small scale of nano-aerial-vehicles （NAV）, which has surpassed its immediate predecessor of micro-aerial-vehicles （MAV）, leaving a vast range of development possi- bilities that MAVs have to offer. Because of the prompt advancement into the NAV research devel- opment, the true potential and challenges presented by MAV development were never solved, understood, and truly uncovered, especially under the influence of transition and low Reynolds number flow characteristics. This paper reviews a part of previous MAV research developments which are deemed important of notification; kinematics, membranes, and flapping mechanisms ranges from small birds to big insects, which resides within the transition and low Reynolds number regimes. This paper also reviews the possibility of applying a piezoelectric transmission used to pro- duce NAV flapping wing motion and mounted on a MAV, replacing the conventional motorized flapping wing transmission. Findings suggest that limited work has been done for MAVs matching these criteria. The preferred research approach has seen bias towards numerical analysis as compared to experimental analysis.
基金supported by the National Natural Science Foundation of China(No.:11572023)。
文摘A three-wing Flapping Wing Rotor Micro Aerial Vehicle(FWR-MAV)which can perform controlled flight is introduced and an experimental study on this vehicle is presented.A mechanically driven flapping rotary mechanism is designed to drive the three flapping wings and generate lift,and control mechanisms are designed to control the pose of the FWR-MAV.A flight control board for attitude control with robust onboard attitude estimation and a control algorithm is also developed to perform stable hovering flight and forward flight.A series of flight tests was conducted,with hovering flight and forward flight tests performed to optimize the control parameters and assess the performance of the FWR-MAV.The hovering flight test shows the ability of the FWR-MAV to counteract the moment generated by rotary motion and maintain the attitude of the FWR-MAV in space;the experiment of forward flight shows that the FWR-MAV can track the desired attitude.
文摘Most insects and hummingbirds can generate lift during both upstroke and downstroke with a nearly horizontal flapping stroke plane,and perform precise hovering flight.Further,most birds can utilize tails and muscles in wings to actively control the flight performance,while insects control their flight with muscles based on wing root along with wing’s passive deformation.Based on the above flight principles of birds and insects,Flapping Wing Micro Air Vehicles(FWMAVs)are classified as either bird-inspired or insect-inspired FWMAVs.In this review,the research achievements on mechanisms of insect-inspired,hoverable FWMAVs over the last ten years(2011-2020)are provided.We also provide the definition,function,research status and development prospect of hoverable FWMAVs.Then discuss it from three aspects:bio-inspiration,motor-driving mechanisms and intelligent actuator-driving mechanisms.Following this,research groups involved in insect-inspired,hoverable FWMAV research and their major achievements are summarized and classified in tables.Problems,trends and challenges about the mechanism are compiled and presented.Finally,this paper presents conclusions about research on mechanical structure,and the future is discussed to enable further research interests.
基金supported by the National Natural Science Foundation of China(Nos.52175277,51905431).
文摘Flying insects are capable of flapping their wings to provide the required power and control forces for flight.A coordinated organizational system including muscles,wings,and control architecture plays a significant role,which provides the sources of inspiration for designing flapping-wing vehicles.In recent years,due to the development of micro-and meso-scale manufacturing technologies,advances in components technologies have directly led to a progress of smaller Flapping-Wing Nano Air Vehicles(FWNAVs)around gram and sub-gram scales,and these air vehicles have gradually acquired insect-like locomotive strategies and capabilities.This paper will present a selective review of components technologies for ultra-lightweight flapping-wing nano air vehicles under 3 g,which covers the novel propulsion methods such as artificial muscles,flight control mechanisms,and the design paradigms of the insect-inspired wings,with a special focus on the development of the driving technologies based on artificial muscles and the progress of the biomimetic wings.The challenges involved in constructing such small flapping-wing air vehicles and recommendations for several possible future directions in terms of component technology enhancements and overall vehicle performance are also discussed in this paper.This review will provide the essential guidelines and the insights for designing a flapping-wing nano air vehicle with higher performance.
文摘The analysis of the passive rotation feature of a micro Flapping Rotary Wing（FRW）applicable for Micro Air Vehicle（MAV） design is presented in this paper. The dynamics of the wing and its influence on aerodynamic performance of FRW is studied at low Reynolds number（~10~3）.The FRW is modeled as a simplified system of three rigid bodies： a rotary base with two flapping wings. The multibody dynamic theory is employed to derive the motion equations for FRW. A quasi-steady aerodynamic model is utilized for the calculation of the aerodynamic forces and moments. The dynamic motion process and the effects of the kinematics of wings on the dynamic rotational equilibrium of FWR and the aerodynamic performances are studied. The results show that the passive rotation motion of the wings is a continuous dynamic process which converges into an equilibrium rotary velocity due to the interaction between aerodynamic thrust, drag force and wing inertia. This causes a unique dynamic time-lag phenomena of lift generation for FRW, unlike the normal flapping wing flight vehicle driven by its own motor to actively rotate its wings. The analysis also shows that in order to acquire a high positive lift generation with high power efficiency and small dynamic time-lag, a relative high mid-up stroke angle within 7–15° and low mid-down stroke angle within -40° to -35° are necessary. The results provide a quantified guidance for design option of FRW together with the optimal kinematics of motion according to flight performance requirement.
基金supported in part by the National Natural Science Foundation of China(62225304,61933001,61921004,62173031)the Beijing Municipal Natural Science Foundation(JQ20026)+1 种基金the Beijing Top Discipline for Artificial Intelligent Science and Engineering,University of Science and Technology Beijing。
文摘Flapping-wing flight, as the distinctive flight method retained by natural flying creatures, contains profound aerodynamic principles and brings great inspirations and encouragements to drone developers. Though some ingenious flapping-wing robots have been designed during the past two decades, development and application of autonomous flapping-wing robots are less successful and still require further research. Here, we report the development of a servo-driven bird-like flapping-wing robot named USTBird-I and its application in autonomous airdrop.Inspired by birds, a camber structure and a dihedral angle adjustment mechanism are introduced into the airfoil design and motion control of the wings, respectively. Computational fluid dynamics simulations and actual flight tests show that this bionic design can significantly improve the gliding performance of the robot, which is beneficial to the execution of the airdrop mission.Finally, a vision-based airdrop experiment has been successfully implemented on USTBird-I, which is the first demonstration of a bird-like flapping-wing robot conducting an outdoor airdrop mission.
基金financial support of the projects from National Key Research and Development Program of China(No.2017YFB1300102)National Natural Science Foundation of China(Nos.11872314 and U1613227)Youth Program of Natural Science Basic Research Plan in Shaanxi Province of China(No.2019JQ-394)。
文摘This paper establishes and analyzes a high-fidelity nonlinear time-periodic dynamic model and the corresponding state observer for flapping vibration suppression of a novel tailless Flapping Wing Micro Air Vehicle(FWMAV),named NPU-Tinybird.Firstly,a complete modeling of NPU-Tinybird is determined,including the aerodynamic model based on the quasi-steady method,the kinematic and dynamic model about the mechanism of flapping and attitude control,combined with the single rigid body dynamic model.Based on this,a linearized longitudinal pitch dynamic cycle-averaged model is obtained and analyzed through the methods of neural network fitting and system identification,preparing for the design of flapping vibration suppression observer.Flapping vibration is an inherent property of the tailless FWMAV,which arises from the influence of time-periodic aerodynamic forces and moments.It can be captured by attitude and position sensors on the plane,which impairs the flight performance and efficiency of flight controller and actuators.To deal with this problem,a novel state observer for flapping vibration suppression is designed.A robust optimal controller based on the linear quadratic theory is also designed to stabilize the closed-loop system.Simulation results are given to verify the performance of the observer,including the closed loop responses combined with robust optimal controller,the comparison of different parameters of observer and the comparison with several classic methods,such as Kalman filter,H-infinity filter and low-pass filter,which prove that the novel observer owns a fairly good suppression effect on flapping vibration and benefits for the improvement of flight performance and control efficiency.
文摘The problem of flapping motion control of Micro Air Vehicles (MAVs) with flapping wings was studied in this paper.Based upon the knowledge of skeletal and muscular components of hummingbird, a dynamic model for flapping wing wasdeveloped.A control scheme inspired by human memory and learning concept was constructed for wing motion control ofMAVs.The salient feature of the proposed control lies in its capabilities to improve the control performance by learning fromexperience and observation on its current and past behaviors, without the need for system dynamic information.Furthermore,the overall control scheme has a fairly simple structure and demands little online computations, making it attractive for real-timeimplementation on MAVs.Both theoretical analysis and computer simulation confirms its effectiveness.
