In this paper,an adaptive sliding mode method was proposed for BTT autopilot of cruise missiles with variable-swept wings. To realize the whole state feedback,the roll angle,normal overloads and angular rates were con...In this paper,an adaptive sliding mode method was proposed for BTT autopilot of cruise missiles with variable-swept wings. To realize the whole state feedback,the roll angle,normal overloads and angular rates were considered as state variables of the autopilot,and a parametric sliding mode controller was designed via feedback linearization. A novel parametric adaptation law was put forward to estimate the nonlinear timevarying parameter perturbations in real time based on Lyapunov stability theory. A sliding mode boundary layer theory was adopted to smooth the discontinuity of control variables and eliminate the control chattering. The simulation was presented for the roll angle and overload commands tracking in different configuration schemes. The results indicated that the controlled system has robust dynamic tracking performance in condition of the large-scale aerodynamic parametric variety resulted from variable-swept wings.展开更多
A new approach to gain-scheduling of H∞controllers is proposed for a cruise missile with variableswept wings( VSW) in bank-to-turn( BTT) mode. A nonlinear dynamic model is established and anticipant performance crite...A new approach to gain-scheduling of H∞controllers is proposed for a cruise missile with variableswept wings( VSW) in bank-to-turn( BTT) mode. A nonlinear dynamic model is established and anticipant performance criterions are given at first. For the selected operating points,feedback robust controllers of threechannels are designed independently to restrain cross-channel couple disturbances and aerodynamic perturbations. Then,the sweepback and Ma number are selected to schedule controller gains iteratively to ensure all closed-loop poles locating inside the desired region. The proposed method here attempts to extend the performance of initial design obtained for a single arbitrary point to the whole linearized domain while maintaining the expected stability over the entire range of sweepback and full flight envelope. Some time-domain analysis procedures based on the proposed method are carried out and assessed,while the performance of tracking and robustness to aerodynamic perturbations in different situations are contrasted by some nonlinear simulations. Finally,the numerical simulations demonstrate that the proposed autopilot design method has better tracking performance and is robust,effective and feasible.展开更多
Aeroelastic control is a critical technique for high-aspect-ratio flexible wings.A novel aeroelastic control method is introduced,utilizing the internal Moving Mass Control(MMC)technique,which demonstrates the potenti...Aeroelastic control is a critical technique for high-aspect-ratio flexible wings.A novel aeroelastic control method is introduced,utilizing the internal Moving Mass Control(MMC)technique,which demonstrates the potential to fulfill hybrid control demands without incurring a drag penalty.Dynamic equations for a flexible wing equipped with a spanwise moving mass under unsteady aerodynamic loading are derived using mass position as the input variable.Controloriented analyses indicate that intrinsic structural frequencies,flutter characteristics,and gust response can be actively modified by varying the spanwise and chordwise positions of the mass element.Among these,the chordwise position exerts a more significant impact on the structural modes and flutter speed of the wing.A hybrid aeroelastic control system,incorporating motion planning and control law,is proposed to evaluate real-time performance in Active Flutter Suppression(AFS)and Gust Load Alleviation(GLA).Control outcomes suggest that,with a mass ratio of 1/16 and a half-chord installation area for the guide rail,flutter speed increases by about 10%.Additionally,excitation amplitudes across different gust frequencies are substantially mitigated,achieving a maximum reduction of vibration amplitude by about 73%.These findings offer a comprehensive understanding of the MMC technique and its application to flexible aircraft.展开更多
Based on research into bionic butterflies for environmental detection and ecological management,a scheme was proposed to develop and manufacture a bionic aircraft with two wings inspired by specific butterfly species....Based on research into bionic butterflies for environmental detection and ecological management,a scheme was proposed to develop and manufacture a bionic aircraft with two wings inspired by specific butterfly species.A flapping-wing aircraft with a simple structure was designed,and its two-wing design was optimized.The research focused on several key areas:the design and optimization of the wings,the development of the transmission mechanism,hardware design and fabrication,and 3D printing for component manufacturing.This resulted in the bionic replication of the wing shape and structure of the Tiger Papilio butterfly.The final bionic butterfly features a wingspan of 29.5 cm and a total weight of 13.8 g.This project integrates mechatronic principles and provides a valuable reference for advancements in the field of bionic butterflies.Future research could explore the aerodynamic characteristics of wings and innovative design approaches in greater depth.展开更多
To meet the challenge of drag reduction for next-generation supersonic transport aircraft,increasing attention has been focused on Natural Laminar Flow(NLF)technology.However,the highly swept wings and high-Reynolds-n...To meet the challenge of drag reduction for next-generation supersonic transport aircraft,increasing attention has been focused on Natural Laminar Flow(NLF)technology.However,the highly swept wings and high-Reynolds-number conditions of such aircraft dramatically amplify Crossflow(CF)instabilities inside boundary layers,making it difficult to maintain a large laminar flow region.To explore novel NLF designs on supersonic wings,this article investigates the mechanisms underlying the attenuation of Tollmien-Schlichting(TS)and CF instabilities by modifying pressure distributions.The evolution of TS and CF instabilities are evaluated under typical pressure distributions with different leading-edge flow acceleration region lengths,pressure coefficient slopes and pressure coefficient deviations.The results show that shortening the leading-edge flow acceleration region and using a flat pressure distribution are favorable for suppressing CF instabilities,and keeping a balance of disturbance growth between positive and negative wave angles is favorable for attenuating TS instabilities.Based on the uncovered mechanisms,a strategy of supersonic NLF design is proposed.Examination of the proposed strategy at a 60°sweep angle and Ma=2 presents potential to exceed the conventional NLF limit and achieve a transition Reynolds number of 17.6million,which can provide guidance for NLF design on supersonic highly swept wings.展开更多
To better understand the aerodynamic reasons for highly organized movements of flying organisms,the three-flapping wing system in tandem formation was studied numerically in this paper.Different from previous relevant...To better understand the aerodynamic reasons for highly organized movements of flying organisms,the three-flapping wing system in tandem formation was studied numerically in this paper.Different from previous relevant studies on the multiple flapping wings that are equally spaced,this study emphasizes the impact of unequal spacing between individuals on the aerodynamics of each individual wing as well as the whole system.It is found that swapping the distance between the first and second wing with the distance between the second wing and the rearmost wing does not affect the overall aerodynamic performance,but significantly changes the distribution of aerodynamic benefits across each wing.During the whole flapping cycle,three effects are at play.The narrow channel effect and the downwash effect can promote and weaken the wing lift,respectively,while the wake capture effect can boost the thrust.It also shows that these effects could be manipulated by changing the spacing between adjacent wings.These findings provide a novel way for flow control in tandem formation flight and are also inspiring for designing the formation flight of bionic aircraft.展开更多
Most flapping-wing aircraft wings use a single degree of freedom to generate lift and thrust by flapping up and down,while relying on the tail control surfaces to manage attitude.However,these aircraft have certain li...Most flapping-wing aircraft wings use a single degree of freedom to generate lift and thrust by flapping up and down,while relying on the tail control surfaces to manage attitude.However,these aircraft have certain limitations,such as poor accuracy in attitude control and inadequate roll control capabilities.This paper presents a design for an active torsional mechanism at the wing's trailing edge,which enables differential variations in the pitch angle of the left and right wings during flapping.This simple mechanical form significantly enhances the aircraft's roll control capacity.The experimental verification of this mechanism was conducted in a wind tunnel using the RoboEagle flapping-wing aerial vehicle that we developed.The study investigated the effects of the control strategy on lift,thrust,and roll moment during flapping flight.Additionally,the impact of roll control on roll moment was examined under various wind speeds,flapping frequencies,angles of attack,and wing flexibility.Furthermore,several rolling maneuver flight tests were performed to evaluate the agility of RoboEagle,utilizing both the elevon control strategy and the new roll control strategy.The results demonstrated that the new roll control strategy effectively enhances the roll control capability,thereby improving the attitude control capabilities of the flapping-wing aircraft in complex wind field environments.This conclusion is supported by a comparison of the control time,maximum roll angle,average roll angular velocity,and other relevant parameters between the two control strategies under identical roll control input.展开更多
The measurement of wing dynamic deformation in morphing aircraft is crucial for achieving closed-loop control and evaluating structural safety.For variable-sweep wings with active large deformation,this paper proposes...The measurement of wing dynamic deformation in morphing aircraft is crucial for achieving closed-loop control and evaluating structural safety.For variable-sweep wings with active large deformation,this paper proposes a novel videogrammetric method for full-field dynamic deformation measurement.A stereo matching method based on epipolar geometry constraint and topological constraint is presented to find the corresponding targets between stereo images.In addition,a new method based on affine transformation combined with adjacent closest point matching is developed,aiming to achieve fast and automatic tracking of targets in time-series images with large deformation.A calculation model for dynamic deformation parameters is established to obtain the displacement,sweep variable angle,and span variation.To verify the proposed method,a dynamic deformation measurement experiment is conducted on a variable-sweep wing model.The results indicate that the actual accuracy of the proposed method is approximately 0.02%of the measured area(e.g.,0.32 mm in a 1.6 m scale).During one morphing course,the sweep variable angle,the span variation and the displacement increase gradually,and then decrease.The maximum sweep variable angle is 36.6°,and the span variation is up to 101.13 mm.The overall configuration of the wing surface is effectively reconstructed under different morphing states.展开更多
Compared to the traditional flapping-wing structure with single motion mode,a micro servoactuator driven Flapping-Wing Air Vehicle(FWAV)breaks free from the limitations imposed by the motion parameters of the crank-co...Compared to the traditional flapping-wing structure with single motion mode,a micro servoactuator driven Flapping-Wing Air Vehicle(FWAV)breaks free from the limitations imposed by the motion parameters of the crank-connecting rod mechanism.It allows for simultaneous control of wings’position and velocity attitude through pulse width modulation,showcasing unrivaled controllability and promising extensive applications.However,this method of motion control also brings new challenges to the design of the wings’motion parameters.This study seeks to investigate the relationship between the motion parameters of micro servoactuator driven FWAV and its aerodynamic characteristics,then explore a servo control method that can optimize its thrust-producing performance.To achieve this,this paper involves the establishment of Amplitude Loss Model(ALM),Flapping Wing Dynamic Model(FWDM),and Power Load Model(PLM),followed by motion capture experiments,dynamic monitoring experiments,and power monitoring experiments.Experimental results show that the proposed modeling method,which fully considers the amplitude loss effect and advanced twisting effect in flapping-wing motion,can accurately calculate thrust,power,and power load,with prediction errors of less than 10%,5%and 13%,respectively.This high-precision model can effectively optimize motion parameters,allowing for better performance of flapping-wing motion.展开更多
This paper proposes a gradient conformal design technique to modify the multi-directional stiffness characteristics of 3D printed chiral metamaterials,using various airfoil shapes.The method ensures the integrity of c...This paper proposes a gradient conformal design technique to modify the multi-directional stiffness characteristics of 3D printed chiral metamaterials,using various airfoil shapes.The method ensures the integrity of chiral cell nodal circles while improving load transmission efficiency and enhancing manufacturing precision for 3D printing applications.A parametric design framework,integrating finite element analysis and optimization modules,is developed to enhance the wing’s multidirectional stiffness.The optimization process demonstrates that the distribution of chiral structural ligaments and nodal circles significantly affects wing deformation.The stiffness gradient optimization results reveal a variation of over 78%in tail stiffness performance between the best and worst parameter combinations.Experimental outcomes suggest that this strategy can develop metamaterials with enhanced deformability,offering a promising approach for designing morphing wings.展开更多
Wingsuit Flying,alsocalled wingsuiting,is a variation of skydiving.In this sport,a person will fly in the air using a special jumpsuit called a wingsuit.This wingsuit comprises of two arm wings and a single leg wing w...Wingsuit Flying,alsocalled wingsuiting,is a variation of skydiving.In this sport,a person will fly in the air using a special jumpsuit called a wingsuit.This wingsuit comprises of two arm wings and a single leg wing which has inflatable nylon cells.The modern wingsuits were developed in the 1990's.They are sometimes referred to as birdman suits or flying squirrel suits.展开更多
The development of a tailless Flapping Wing Micro Aerial Vehicle(FWMAV)inspired by the hummingbird is presented in this work.By implementing mechanical simplifications,it is possible to use planar machining technology...The development of a tailless Flapping Wing Micro Aerial Vehicle(FWMAV)inspired by the hummingbird is presented in this work.By implementing mechanical simplifications,it is possible to use planar machining technology for manufacturing of the FWMAV’s body,greatly reducing assembly errors.Traditionally,studies on flapping wing aircraft are limited to open-loop wing kinematics control.In this work,an instantaneous closed-loop wing trajectory tracking control system is introduced to minimize wings’trajectory tracking errors.The control system is based on Field-Oriented Control(FOC)with a loop shaping compensation technique near the flapping frequency.Through frequency analysis,the loop shaping compensator ensures the satisfactory bandwidth and performance for the closed-loop flapping system.To implement the proposed controller,a compact autopilot board integrated with FOC hardware is designed,weighing only 2.5 g.By utilizing precise wing trajectory tracking control,the hummingbird-inspired FWMAV demonstrates superior ability to resist external disturbances and exhibits reduced attitude tracking errors during hovering flight compared to the open-loop wing motion.展开更多
High-aspect-ratio aircraft are widely used in military and civilian fields,such as reconnaissance,surveillance,and attacks,due to their high lift-to-drag ratio,strong payload capability,significant endurance effect,an...High-aspect-ratio aircraft are widely used in military and civilian fields,such as reconnaissance,surveillance,and attacks,due to their high lift-to-drag ratio,strong payload capability,significant endurance effect,and good stealth performance.However,compared to conventional aircraft,high-aspect-ratio aircraft are more susceptible to gust disturbances during flight.In response to this phenomenon,a full-scale dynamic model of a high-aspect-ratio unmanned aerial vehicle was developed.Considering the coupling among control surfaces,structural forces,and aerodynamic forces,along with sensor,actuator,and delay effects,an H_(∞)control law was designed using the principle of singular value energy flow reduction and weighted function,with a PID(Proportional-Integral-Derivative)control law for comparison.The two controllers were then subjected to pulse-response and jury stability tests.Finally,wind tunnel tests were conducted to investigate the gust alleviation principle,in which gust disturbances were generated using gust generators and control surface self-excitation.The results present that the average wing root bending moment and wing tip overload under the PID control law decrease by approximately 30%,while under the H_(∞)control law,both the average wing root bending moment and wing tip overload reduction rate exceed 50%,with peaks reaching 60%.This validates the feasibility and efficiency of the designed H_(∞)controller.展开更多
The design of unmanned aerial vehicles(UAVs)revolves around the careful selection of materials that are both lightweight and robust.Carbon fiber-reinforced polymer(CFRP)emerged as an ideal option for wing construction...The design of unmanned aerial vehicles(UAVs)revolves around the careful selection of materials that are both lightweight and robust.Carbon fiber-reinforced polymer(CFRP)emerged as an ideal option for wing construction,with its mechanical qualities thoroughly investigated.In this study,we developed and optimized a conceptual UAV wing to withstand structural loads by establishing progressive composite stacking sequences,and we conducted a series of experimental characterizations on the resulting material.In the optimization phase,the objective was defined as weight reduction,while the Hashin damage criterion was established as the constraint for the optimization process.The optimization algorithm adaptively monitors regional damage criterion values,implementing necessary adjustments to facilitate the mitigation process in a cost-effective manner.Optimization of the analytical model using Simulia Abaqus~(TM)and a Python-based user-defined sub-routine resulted in a 34.7%reduction in the wing's structural weight after 45 iterative rounds.Then,the custom-developed optimization algorithm was compared with a genetic algorithm optimization.This comparison has demonstrated that,although the genetic algorithm explores numerous possibilities through hybridization,the custom-developed algorithm is more result-oriented and achieves optimization in a reduced number of steps.To validate the structural analysis,test specimens were fabricated from the wing's most critically loaded segment,utilizing the identical stacking sequence employed in the optimization studies.Rigorous mechanical testing revealed unexpectedly high compressive strength,while tensile and bending strengths fell within expected ranges.All observed failure loads remained within the established safety margins,thereby confirming the reliability of the analytical predictions.展开更多
Avian wings are central to their remarkable flight ability and diverse life history strategies,including behaviors such as fighting and mating.These multifaceted functions are intricately tied to wing shape,which vari...Avian wings are central to their remarkable flight ability and diverse life history strategies,including behaviors such as fighting and mating.These multifaceted functions are intricately tied to wing shape,which varies significantly across species because of the complex interplay of evolutionary and ecological pressures.Many indices have been developed to quantify wing characteristics to facilitate the study and comparison of avian wing morphology across species.This study provides a comprehensive overview of existing quantitative methods for analyzing avian wing shapes.We then constructed a new quantification framework through the beta distribution,which can generate indices reflecting the shape of avian wings(center,dispersion,skewness,and kurtosis).Next,we used the flight feathers of 613 bird species to perform different quantitative analyses and explore the relationships between various wing shape quantification methods and life history traits,which serve as proxies for the selective forces shaping wing morphology.We find that the wing shape indices are more strongly associated with ecological variables than with morphological variables,especially for migration,habitat and territoriality.This research guides the selection of appropriate methods for wing shape analysis,contributing to a deeper understanding of avian morphology and its evolutionary drivers.展开更多
The ability of queens and males of most ant species to disperse by flight has fundamentally contributed to the group’s evolutionary and ecological success and is a determining factor to take into account for biogeogr...The ability of queens and males of most ant species to disperse by flight has fundamentally contributed to the group’s evolutionary and ecological success and is a determining factor to take into account for biogeographic studies(Wagner and Liebherr 1992;Peeters and Ito 2001;Helms 2018).展开更多
基金Sponsored by the National Natural Science Foundation of China(Grant No.11176012)Aviation Science Foundation of China(Grant No.20110159001)
文摘In this paper,an adaptive sliding mode method was proposed for BTT autopilot of cruise missiles with variable-swept wings. To realize the whole state feedback,the roll angle,normal overloads and angular rates were considered as state variables of the autopilot,and a parametric sliding mode controller was designed via feedback linearization. A novel parametric adaptation law was put forward to estimate the nonlinear timevarying parameter perturbations in real time based on Lyapunov stability theory. A sliding mode boundary layer theory was adopted to smooth the discontinuity of control variables and eliminate the control chattering. The simulation was presented for the roll angle and overload commands tracking in different configuration schemes. The results indicated that the controlled system has robust dynamic tracking performance in condition of the large-scale aerodynamic parametric variety resulted from variable-swept wings.
基金Sponsored by Armament Department Pre-Research Foundation of China(Grant No.9140A31010114JB25465)Natural Science Foundation of Jiangsu Province(Grant No.BK20140795)Chinese Aerospace CAST Innovation Foundation(Grant No.CAST2014-27)
文摘A new approach to gain-scheduling of H∞controllers is proposed for a cruise missile with variableswept wings( VSW) in bank-to-turn( BTT) mode. A nonlinear dynamic model is established and anticipant performance criterions are given at first. For the selected operating points,feedback robust controllers of threechannels are designed independently to restrain cross-channel couple disturbances and aerodynamic perturbations. Then,the sweepback and Ma number are selected to schedule controller gains iteratively to ensure all closed-loop poles locating inside the desired region. The proposed method here attempts to extend the performance of initial design obtained for a single arbitrary point to the whole linearized domain while maintaining the expected stability over the entire range of sweepback and full flight envelope. Some time-domain analysis procedures based on the proposed method are carried out and assessed,while the performance of tracking and robustness to aerodynamic perturbations in different situations are contrasted by some nonlinear simulations. Finally,the numerical simulations demonstrate that the proposed autopilot design method has better tracking performance and is robust,effective and feasible.
基金supported by the National Natural Science Foundation of China(No.12102096)the Guangdong Basic and Applied Basic Research Foundation,China(No.2022A1515011885)the Research Fund of National Key Laboratory of Aerospace Physics in Fluids,China(No.2024-APF-KFQMJJ-08)。
文摘Aeroelastic control is a critical technique for high-aspect-ratio flexible wings.A novel aeroelastic control method is introduced,utilizing the internal Moving Mass Control(MMC)technique,which demonstrates the potential to fulfill hybrid control demands without incurring a drag penalty.Dynamic equations for a flexible wing equipped with a spanwise moving mass under unsteady aerodynamic loading are derived using mass position as the input variable.Controloriented analyses indicate that intrinsic structural frequencies,flutter characteristics,and gust response can be actively modified by varying the spanwise and chordwise positions of the mass element.Among these,the chordwise position exerts a more significant impact on the structural modes and flutter speed of the wing.A hybrid aeroelastic control system,incorporating motion planning and control law,is proposed to evaluate real-time performance in Active Flutter Suppression(AFS)and Gust Load Alleviation(GLA).Control outcomes suggest that,with a mass ratio of 1/16 and a half-chord installation area for the guide rail,flutter speed increases by about 10%.Additionally,excitation amplitudes across different gust frequencies are substantially mitigated,achieving a maximum reduction of vibration amplitude by about 73%.These findings offer a comprehensive understanding of the MMC technique and its application to flexible aircraft.
基金2023 Innovation and Entrepreneurship Training Project of Hunan College Students:Tiger Butterfly—Bionic Manufacturing and Morphology Research(Project No.S202313809022)Key Project of Education Reform of Hunan Provincial Department of Education:Research on Disciplinary Integration Education Model under Intelligence+Empowerment—A Case Study of Robotics and Logistics Management Majors(Project No.HNJG-20231561)。
文摘Based on research into bionic butterflies for environmental detection and ecological management,a scheme was proposed to develop and manufacture a bionic aircraft with two wings inspired by specific butterfly species.A flapping-wing aircraft with a simple structure was designed,and its two-wing design was optimized.The research focused on several key areas:the design and optimization of the wings,the development of the transmission mechanism,hardware design and fabrication,and 3D printing for component manufacturing.This resulted in the bionic replication of the wing shape and structure of the Tiger Papilio butterfly.The final bionic butterfly features a wingspan of 29.5 cm and a total weight of 13.8 g.This project integrates mechatronic principles and provides a valuable reference for advancements in the field of bionic butterflies.Future research could explore the aerodynamic characteristics of wings and innovative design approaches in greater depth.
基金supported by the National Natural Science Foundation of China(No.12072285)the National Key Research and Development Program of China(No.2023YFB3002800)the Youth Innovation Team of Shaanxi Universities,China。
文摘To meet the challenge of drag reduction for next-generation supersonic transport aircraft,increasing attention has been focused on Natural Laminar Flow(NLF)technology.However,the highly swept wings and high-Reynolds-number conditions of such aircraft dramatically amplify Crossflow(CF)instabilities inside boundary layers,making it difficult to maintain a large laminar flow region.To explore novel NLF designs on supersonic wings,this article investigates the mechanisms underlying the attenuation of Tollmien-Schlichting(TS)and CF instabilities by modifying pressure distributions.The evolution of TS and CF instabilities are evaluated under typical pressure distributions with different leading-edge flow acceleration region lengths,pressure coefficient slopes and pressure coefficient deviations.The results show that shortening the leading-edge flow acceleration region and using a flat pressure distribution are favorable for suppressing CF instabilities,and keeping a balance of disturbance growth between positive and negative wave angles is favorable for attenuating TS instabilities.Based on the uncovered mechanisms,a strategy of supersonic NLF design is proposed.Examination of the proposed strategy at a 60°sweep angle and Ma=2 presents potential to exceed the conventional NLF limit and achieve a transition Reynolds number of 17.6million,which can provide guidance for NLF design on supersonic highly swept wings.
基金supported by the National Natural Science Foundation of China(Grant No.12172276)Shaanxi key research and development program(Grant No.2022ZDLGY02-07).
文摘To better understand the aerodynamic reasons for highly organized movements of flying organisms,the three-flapping wing system in tandem formation was studied numerically in this paper.Different from previous relevant studies on the multiple flapping wings that are equally spaced,this study emphasizes the impact of unequal spacing between individuals on the aerodynamics of each individual wing as well as the whole system.It is found that swapping the distance between the first and second wing with the distance between the second wing and the rearmost wing does not affect the overall aerodynamic performance,but significantly changes the distribution of aerodynamic benefits across each wing.During the whole flapping cycle,three effects are at play.The narrow channel effect and the downwash effect can promote and weaken the wing lift,respectively,while the wake capture effect can boost the thrust.It also shows that these effects could be manipulated by changing the spacing between adjacent wings.These findings provide a novel way for flow control in tandem formation flight and are also inspiring for designing the formation flight of bionic aircraft.
基金supported by National Natural Science Foundation of China under Grants No.52175277 and 12272318ND Basic Research Funds under Grants G2022WD,Key R&D Program in Shaanxi Province of China under Grant No.2023-YBGY-372.
文摘Most flapping-wing aircraft wings use a single degree of freedom to generate lift and thrust by flapping up and down,while relying on the tail control surfaces to manage attitude.However,these aircraft have certain limitations,such as poor accuracy in attitude control and inadequate roll control capabilities.This paper presents a design for an active torsional mechanism at the wing's trailing edge,which enables differential variations in the pitch angle of the left and right wings during flapping.This simple mechanical form significantly enhances the aircraft's roll control capacity.The experimental verification of this mechanism was conducted in a wind tunnel using the RoboEagle flapping-wing aerial vehicle that we developed.The study investigated the effects of the control strategy on lift,thrust,and roll moment during flapping flight.Additionally,the impact of roll control on roll moment was examined under various wind speeds,flapping frequencies,angles of attack,and wing flexibility.Furthermore,several rolling maneuver flight tests were performed to evaluate the agility of RoboEagle,utilizing both the elevon control strategy and the new roll control strategy.The results demonstrated that the new roll control strategy effectively enhances the roll control capability,thereby improving the attitude control capabilities of the flapping-wing aircraft in complex wind field environments.This conclusion is supported by a comparison of the control time,maximum roll angle,average roll angular velocity,and other relevant parameters between the two control strategies under identical roll control input.
基金supported by the National Natural Science Foundation of China(Grant No.12202282).
文摘The measurement of wing dynamic deformation in morphing aircraft is crucial for achieving closed-loop control and evaluating structural safety.For variable-sweep wings with active large deformation,this paper proposes a novel videogrammetric method for full-field dynamic deformation measurement.A stereo matching method based on epipolar geometry constraint and topological constraint is presented to find the corresponding targets between stereo images.In addition,a new method based on affine transformation combined with adjacent closest point matching is developed,aiming to achieve fast and automatic tracking of targets in time-series images with large deformation.A calculation model for dynamic deformation parameters is established to obtain the displacement,sweep variable angle,and span variation.To verify the proposed method,a dynamic deformation measurement experiment is conducted on a variable-sweep wing model.The results indicate that the actual accuracy of the proposed method is approximately 0.02%of the measured area(e.g.,0.32 mm in a 1.6 m scale).During one morphing course,the sweep variable angle,the span variation and the displacement increase gradually,and then decrease.The maximum sweep variable angle is 36.6°,and the span variation is up to 101.13 mm.The overall configuration of the wing surface is effectively reconstructed under different morphing states.
基金supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.51521003)the Natural Science Foundation of Heilongjiang Province(No.ZD2023E002)+1 种基金HIT Wuhu Robot Technology Research Institute(No.HIT-CXY-CMP2-RVJDT-21-01)the Open Fund for Laboratory of Aerospace Servo Actuation and Transmission(No.LASAT-2022-A01-02).
文摘Compared to the traditional flapping-wing structure with single motion mode,a micro servoactuator driven Flapping-Wing Air Vehicle(FWAV)breaks free from the limitations imposed by the motion parameters of the crank-connecting rod mechanism.It allows for simultaneous control of wings’position and velocity attitude through pulse width modulation,showcasing unrivaled controllability and promising extensive applications.However,this method of motion control also brings new challenges to the design of the wings’motion parameters.This study seeks to investigate the relationship between the motion parameters of micro servoactuator driven FWAV and its aerodynamic characteristics,then explore a servo control method that can optimize its thrust-producing performance.To achieve this,this paper involves the establishment of Amplitude Loss Model(ALM),Flapping Wing Dynamic Model(FWDM),and Power Load Model(PLM),followed by motion capture experiments,dynamic monitoring experiments,and power monitoring experiments.Experimental results show that the proposed modeling method,which fully considers the amplitude loss effect and advanced twisting effect in flapping-wing motion,can accurately calculate thrust,power,and power load,with prediction errors of less than 10%,5%and 13%,respectively.This high-precision model can effectively optimize motion parameters,allowing for better performance of flapping-wing motion.
基金Supported by National Natural Science Foundation of China(Grant Nos.52075026 and 52192632)the Fundamental Research Funds for the Central Universities(Grant No.YWF-22-L-1119)。
文摘This paper proposes a gradient conformal design technique to modify the multi-directional stiffness characteristics of 3D printed chiral metamaterials,using various airfoil shapes.The method ensures the integrity of chiral cell nodal circles while improving load transmission efficiency and enhancing manufacturing precision for 3D printing applications.A parametric design framework,integrating finite element analysis and optimization modules,is developed to enhance the wing’s multidirectional stiffness.The optimization process demonstrates that the distribution of chiral structural ligaments and nodal circles significantly affects wing deformation.The stiffness gradient optimization results reveal a variation of over 78%in tail stiffness performance between the best and worst parameter combinations.Experimental outcomes suggest that this strategy can develop metamaterials with enhanced deformability,offering a promising approach for designing morphing wings.
文摘Wingsuit Flying,alsocalled wingsuiting,is a variation of skydiving.In this sport,a person will fly in the air using a special jumpsuit called a wingsuit.This wingsuit comprises of two arm wings and a single leg wing which has inflatable nylon cells.The modern wingsuits were developed in the 1990's.They are sometimes referred to as birdman suits or flying squirrel suits.
基金support by the National Natural Science Foundation of China(No.62073217,No.61871266)the Fund of the Ministry of Education of the People’s Republic of China(6141A02022607,6141A020227)the Fund of the Professional Technical Service Platform of Shanghai(19DZ2291103).
文摘The development of a tailless Flapping Wing Micro Aerial Vehicle(FWMAV)inspired by the hummingbird is presented in this work.By implementing mechanical simplifications,it is possible to use planar machining technology for manufacturing of the FWMAV’s body,greatly reducing assembly errors.Traditionally,studies on flapping wing aircraft are limited to open-loop wing kinematics control.In this work,an instantaneous closed-loop wing trajectory tracking control system is introduced to minimize wings’trajectory tracking errors.The control system is based on Field-Oriented Control(FOC)with a loop shaping compensation technique near the flapping frequency.Through frequency analysis,the loop shaping compensator ensures the satisfactory bandwidth and performance for the closed-loop flapping system.To implement the proposed controller,a compact autopilot board integrated with FOC hardware is designed,weighing only 2.5 g.By utilizing precise wing trajectory tracking control,the hummingbird-inspired FWMAV demonstrates superior ability to resist external disturbances and exhibits reduced attitude tracking errors during hovering flight compared to the open-loop wing motion.
基金supported by the National Natural Science Foundation of China(Nos.12272104,U22B2013).
文摘High-aspect-ratio aircraft are widely used in military and civilian fields,such as reconnaissance,surveillance,and attacks,due to their high lift-to-drag ratio,strong payload capability,significant endurance effect,and good stealth performance.However,compared to conventional aircraft,high-aspect-ratio aircraft are more susceptible to gust disturbances during flight.In response to this phenomenon,a full-scale dynamic model of a high-aspect-ratio unmanned aerial vehicle was developed.Considering the coupling among control surfaces,structural forces,and aerodynamic forces,along with sensor,actuator,and delay effects,an H_(∞)control law was designed using the principle of singular value energy flow reduction and weighted function,with a PID(Proportional-Integral-Derivative)control law for comparison.The two controllers were then subjected to pulse-response and jury stability tests.Finally,wind tunnel tests were conducted to investigate the gust alleviation principle,in which gust disturbances were generated using gust generators and control surface self-excitation.The results present that the average wing root bending moment and wing tip overload under the PID control law decrease by approximately 30%,while under the H_(∞)control law,both the average wing root bending moment and wing tip overload reduction rate exceed 50%,with peaks reaching 60%.This validates the feasibility and efficiency of the designed H_(∞)controller.
基金supported by the Istanbul Technical University Office of Scientific Research Projects(ITUBAPSIS),under grant MYL-2022-43776。
文摘The design of unmanned aerial vehicles(UAVs)revolves around the careful selection of materials that are both lightweight and robust.Carbon fiber-reinforced polymer(CFRP)emerged as an ideal option for wing construction,with its mechanical qualities thoroughly investigated.In this study,we developed and optimized a conceptual UAV wing to withstand structural loads by establishing progressive composite stacking sequences,and we conducted a series of experimental characterizations on the resulting material.In the optimization phase,the objective was defined as weight reduction,while the Hashin damage criterion was established as the constraint for the optimization process.The optimization algorithm adaptively monitors regional damage criterion values,implementing necessary adjustments to facilitate the mitigation process in a cost-effective manner.Optimization of the analytical model using Simulia Abaqus~(TM)and a Python-based user-defined sub-routine resulted in a 34.7%reduction in the wing's structural weight after 45 iterative rounds.Then,the custom-developed optimization algorithm was compared with a genetic algorithm optimization.This comparison has demonstrated that,although the genetic algorithm explores numerous possibilities through hybridization,the custom-developed algorithm is more result-oriented and achieves optimization in a reduced number of steps.To validate the structural analysis,test specimens were fabricated from the wing's most critically loaded segment,utilizing the identical stacking sequence employed in the optimization studies.Rigorous mechanical testing revealed unexpectedly high compressive strength,while tensile and bending strengths fell within expected ranges.All observed failure loads remained within the established safety margins,thereby confirming the reliability of the analytical predictions.
基金supported by the National Natural Science Foundation of China(No.32170491)the Scientific Research Team Project of the College of Life Sciences,Beijing Normal University in 2024。
文摘Avian wings are central to their remarkable flight ability and diverse life history strategies,including behaviors such as fighting and mating.These multifaceted functions are intricately tied to wing shape,which varies significantly across species because of the complex interplay of evolutionary and ecological pressures.Many indices have been developed to quantify wing characteristics to facilitate the study and comparison of avian wing morphology across species.This study provides a comprehensive overview of existing quantitative methods for analyzing avian wing shapes.We then constructed a new quantification framework through the beta distribution,which can generate indices reflecting the shape of avian wings(center,dispersion,skewness,and kurtosis).Next,we used the flight feathers of 613 bird species to perform different quantitative analyses and explore the relationships between various wing shape quantification methods and life history traits,which serve as proxies for the selective forces shaping wing morphology.We find that the wing shape indices are more strongly associated with ecological variables than with morphological variables,especially for migration,habitat and territoriality.This research guides the selection of appropriate methods for wing shape analysis,contributing to a deeper understanding of avian morphology and its evolutionary drivers.
基金funded by the“Departments of Excellence”program of the Italian Ministry for University and Research(MIUR,2018-2022 and MUR,2023-2027).
文摘The ability of queens and males of most ant species to disperse by flight has fundamentally contributed to the group’s evolutionary and ecological success and is a determining factor to take into account for biogeographic studies(Wagner and Liebherr 1992;Peeters and Ito 2001;Helms 2018).
