More than seventy years before airplanes were invented,a twelve⁃year⁃old girl named Ada Lovelace dreamed of flying.She studied birds and experimented with materials to make wings,even writing a guide called Flyology.B...More than seventy years before airplanes were invented,a twelve⁃year⁃old girl named Ada Lovelace dreamed of flying.She studied birds and experimented with materials to make wings,even writing a guide called Flyology.But her curiosity didnt stop there.展开更多
The evaporation behaviors are crucial for the flame location estimation in liquid rocketengines.This work,for the first time,experimentally reports the sub-millimeter droplet evaporationcharacteristics of the corrosiv...The evaporation behaviors are crucial for the flame location estimation in liquid rocketengines.This work,for the first time,experimentally reports the sub-millimeter droplet evaporationcharacteristics of the corrosive dinitrogen tetroxide(NTO,one prevailing hypergolic oxidizer)athigh ambient pressure up to 4.5 MPa.An in-house corrosion-resistant droplet generator is usedto generate isolated flying droplets of sub-millimeter size,which are then exposed in a gas environ-ment with temperatures between 1010 K and 1210 K and pressures in the range between 2.0 MPaand 4.5 MPa,provided by an optical rapid compression machine.Parallelly,a theoretical modelconsidering both the droplet ambient convection and the NTO dissociation is developed.Resultsindicate that firstly,the present theoretical model that considers the transient droplet-ambient con-vection as well as the temperature and pressure dependent rate of dissociation shows good agree-ment with the experimentally observed droplet lifetime.In addition,the flying droplets velocityregress gradually due to momentum exchange with the ambient,which is more prominent at higherpressure.The evaporation caused droplet size reduction is consistent with the classical D^(2)-law pre-diction,in the present temperature and pressure range.Finally,higher temperature and pressureaccelerate the evaporation and an empirical correlation for the temperature and pressure dependentevaporation rate constant is proposed,which shows good agreement with experiment and simula-tion results.展开更多
The flying-wing aircraft has excellent aerodynamic efficiency and stealth performance.However,due to the lack of tails,the flying-wing aircraft has a serious attitude control problem.In this paper,the effective flow c...The flying-wing aircraft has excellent aerodynamic efficiency and stealth performance.However,due to the lack of tails,the flying-wing aircraft has a serious attitude control problem.In this paper,the effective flow control strategy of three-axis control is proposed by using continuous jets for a flapless flying-wing aircraft.The wind tunnel test of two kinds of flying-wing models,namely one flow control model and one mechanical control model,is conducted,and the control effect is analyzed and compared.By simultaneous blowing of the circulation control actuators inboard and differential blowing of the circulation control actuators outboard,the pitch and roll controls are achieved,respectively.It also has an effective control effect at very large angles of attack where the conventional control surface fails.A linear relationship is found between the increment of the controlled aerodynamic force/moment coefficient and the momentum coefficient for circulation control actuators.Moreover,to resolve the difficulty in yaw control,a novel wingtip jet is proposed based on the concept of the all-moving tip and compared with apex jet and circulation control jet.It is found that the wingtip jet is the most efficient actuator,followed by the simultaneous-blowing circulation control jet.Therefore,based on the research above,two optimized fluidic control configurations are proposed.One employs circulation control jet and wingtip jet,and the other is completely dependent on circulation control jet.Finally,the flow control mechanism of circulation control is discussed.Circulation control significantly accelerates the flow on the upper surface of the airfoil in attached flow and reduces the flow separation region in separated flow,leading to aerodynamic performance improvement.These results provide an important theoretic basis for the flapless flight control of flying-wing aircraft.展开更多
To address the challenges of long commuting times,traffic congestion,high energy consumption,and emissions in inter-city travel,a new type of flying coach has been developed.This innovation aims to significantly short...To address the challenges of long commuting times,traffic congestion,high energy consumption,and emissions in inter-city travel,a new type of flying coach has been developed.This innovation aims to significantly shorten inter-city commuting times,enhance travel efficiency,and simultaneously reduce energy consumption and emissions.The flying coach integrates rail power supply technology,an intelligent operating system,and advanced new materials,comprising a catenary power supply guide rod and various sensor components.Based on analysis of traditional aircraft design principles,the research team simulated the design of the rail-powered flying coach using software such as AutoCAD and SolidWorks for three-dimensional modeling.The analysis results indicate that,compared to traditional aircraft and rail trains,the design of the new flying coach reduces its overall weight while maintaining carrying capacity,thereby improving commuting efficiency and environmental performance.This development lays a solid foundation for creating a greener,more efficient,and convenient inter-city transportation network.展开更多
In response to the need for a supportive on-orbit platform for future Mars exploration missions,this paper proposes the design and implementation of an autonomous spacecraft formation flying system near the Martian sy...In response to the need for a supportive on-orbit platform for future Mars exploration missions,this paper proposes the design and implementation of an autonomous spacecraft formation flying system near the Martian synchronous orbit using fuzzy learning-based intelligent control.A detailed analysis of spacecraft relative motion in the Mars environment is conducted,deducing the necessary conditions to reach the Martian synchronous orbit constraints.The modified Clohessy-Wiltshire(C-W)equation with Martian J_(2)(Oblateness index)perturbation is used as a reference to design a fuzzy learning-based intelligent and robust nonlinear control approach,which helps to autonomously track the desired formation configuration and stabilizes it.An introduction to spacecraft propulsion mechanisms is provided to analyze the feasibility of using electrical thrusters for spacecraft formation configuration tracking and stabilization in Martian synchronous orbits.The simulations show the effectiveness of the proposed control system for long-term on-orbit operations and reveal its reliability for designing intelligent deep-space formation flying configurations,such as an autonomous Mars observatory,a Martian telescope,or an interferometer.展开更多
This paper investigates the configuration design associated with boundary-constrained swarm flying.An analytic swarm configuration is identified to ensure the passive safety between each pair of spacecraft in the radi...This paper investigates the configuration design associated with boundary-constrained swarm flying.An analytic swarm configuration is identified to ensure the passive safety between each pair of spacecraft in the radial-cross-track plane.For the first time,this work derives the explicit configurable spacecraft amount to clarify the configuration's accommodation capacity while considering the maximum inter-spacecraft separation constraint.For larger-scale design problem that involves hundreds of spacecraft,this paper proposes an optimization framework that integrates a Relative Orbit Element(ROE)affine transformation operation and successional convex optimization.The framework establishes a multi-subcluster swarm structure,allowing decoupling the maintenance issues of each subcluster.Compared with previous design methods,it ensures that the computational cost for constraints verification only scales linearly with the swarm size,while also preserving the configuration optimization capacities.Numerical simulations demonstrate that the proposed analytic configuration strictly meets the design constraints.It is also shown that the proposed framework reduces the handled constraint amount by two orders compared with direct optimization,while achieving a remarkable swarm safety enhancement based on the existing analytic configuration.展开更多
Tiltrotors have three flight modes that pose control problems and quality defects during the conversion process.To address this,a novel flying qualities-based time-varying stability augmentation system is designed to ...Tiltrotors have three flight modes that pose control problems and quality defects during the conversion process.To address this,a novel flying qualities-based time-varying stability augmentation system is designed to achieve multi-mode,nonlinear,and time-varying stability.The system integrates a nonlinear time-varying control law with the flying qualities requirements for all three flight modes.It consists of an inner and outer loop control framework,where the control law in the inner loop is designed based on the Lyapunov theorem of stability.The reference models in the outer loop are derived from the flying qualities criteria to meet level one flying qualities requirements.To evaluate the conversion process,a time-varying flying qualities evaluation method is developed,which includes the conversion path,pilot model,and time-varying flying qualities index.The proposed time-varying stability augmentation control system is then tested through simulation during the conversion process.A pilot-aircraft closed-loop system is established for conducting experiments.Comparison between simulation results and pilot-in-loop experiment results demonstrates the effectiveness of the proposed control system.Furthermore,it proves that the evaluation method is suitable for analyzing time-varying systems.This research can be valuable in designing and evaluating stability augmentation controls for strongly time-varying systems.展开更多
Herein,a control method based on the optimal energy efficiency of a hydraulic quadruped robot was proposed,which not only realizes the optimal energy efficiency of flying trot gait but also ensures the stability of hi...Herein,a control method based on the optimal energy efficiency of a hydraulic quadruped robot was proposed,which not only realizes the optimal energy efficiency of flying trot gait but also ensures the stability of high-speed movement.Concretely,the energy consumption per unit distance was adopted as the energy efficiency evaluation index based on the constant pressure oil supply characteristics of the hydraulic system,and the global optimization algorithm was adopted to solve the optimal parameters.Afterward,the gait parameters that affect the energy efficiency of quadruped were analyzed and the mapping relationship between each parameter and energy efficiency was captured,so as to select the optimum combination of energy efficiency parameters,which is significant to improve endurance capability.Furthermore,to ensure the stability of the high-speed flying trot gait motion of the hydraulic quadruped robot,the active compliance control strategy was employed.Lastly,the proposed method was successfully verified by simulations and experiments.The experimental results reveal that the flying trot gait of the hydraulic quadruped robot can be stably controlled at a speed of 2.2 m/s.展开更多
The flying foxes optimization(FFO)algorithm,as a newly introduced metaheuristic algorithm,is inspired by the survival tactics of flying foxes in heat wave environments.FFO preferentially selects the best-performing in...The flying foxes optimization(FFO)algorithm,as a newly introduced metaheuristic algorithm,is inspired by the survival tactics of flying foxes in heat wave environments.FFO preferentially selects the best-performing individuals.This tendency will cause the newly generated solution to remain closely tied to the candidate optimal in the search area.To address this issue,the paper introduces an opposition-based learning-based search mechanism for FFO algorithm(IFFO).Firstly,this paper introduces niching techniques to improve the survival list method,which not only focuses on the adaptability of individuals but also considers the population’s crowding degree to enhance the global search capability.Secondly,an initialization strategy of opposition-based learning is used to perturb the initial population and elevate its quality.Finally,to verify the superiority of the improved search mechanism,IFFO,FFO and the cutting-edge metaheuristic algorithms are compared and analyzed using a set of test functions.The results prove that compared with other algorithms,IFFO is characterized by its rapid convergence,precise results and robust stability.展开更多
The current academic research on the Dian Shi Zhai Pictorial founded in 1884 has been perfected,but there is very little research on the Flying Shadow Pavilion Pictorial,which can be said to be derived from Dian Shi Z...The current academic research on the Dian Shi Zhai Pictorial founded in 1884 has been perfected,but there is very little research on the Flying Shadow Pavilion Pictorial,which can be said to be derived from Dian Shi Zhai Pictorial terms of both content and form,and which was founded by the Haiist painter Wu Youru in 1890 in order to reward the increasing number of admirers,but it is still in the initial stage.Flying Shadow Pavilion Pictorial consisted of four parts:pictures of ladies in Shanghai costumes,news about current affairs,pictures of animals,and compilations of women,each of which was accompanied by the then popular notebooks,which were popular at the time among the then readers because of the matching of pictures with text and the mixing of narratives and discussions.This paper takes Flying Shadow Pavilion Pictorial as the main object,summarizes the existing literature about Flying Shadow Pavilion Pictorial,points out the deficiencies of the current research on this basis,and points out the development trend of Flying Shadow Pavilion Pictorial in the future research.展开更多
During the process of aircraft design, the mathematical model of pilot control behavior characteristics is always used to predict aircraft flying qualities （FQ）. This is one of the important methods to avoid pilot-a...During the process of aircraft design, the mathematical model of pilot control behavior characteristics is always used to predict aircraft flying qualities （FQ）. This is one of the important methods to avoid pilot-aircraft adverse coupling. In order to study the FQ criterion based on closed-loop pilot-aircraft systems, first, an experimental database is built, which includes 40 aircraft dynamics configurations and the corresponding flight simulation results. Second, the mathematical pilot models with a set of different aircraft configurations are obtained by this experimental database. Then, two FQ criteria, Neal-Smith criterion and Moscow Aviation Institute （MAI） criterion, are analyzed. And the relationship between the FQ level evaluated by actual pilot and the parameters of closed-loop pilot-aircraft systems is studied. Finally, an improved criterion of aircraft FQ is built based on the above two criteria. This new criterion is further used to predict FQ for four new aircraft dynamics configurations, and the prediction results verify its accuracy and practicability.展开更多
In this paper a unified control-oriented modeling approach is proposed to deal with the kinematics, linear and angular momentum, contact constraints and dynamics of a free-flying space robot interacting with a target ...In this paper a unified control-oriented modeling approach is proposed to deal with the kinematics, linear and angular momentum, contact constraints and dynamics of a free-flying space robot interacting with a target satellite. This developed approach combines the dynamics of both systems in one structure along with holonomic and nonholonomic constraints in a single framework. Furthermore, this modeling allows consid-ering the generalized contact forces between the space robot end-effecter and the target satellite as internal forces rather than external forces. As a result of this approach, linear and angular momentum will form holonomic and nonholonomic constraints, respectively. Meanwhile, restricting the motion of the space robot end-effector on the surface of the target satellite will impose geometric constraints. The proposed momentum of the combined system under consideration is a generalization of the momentum model of a free-flying space robot. Based on this unified model, three reduced models are developed. The first reduced dynamics can be considered as a generalization of a free-flying robot without contact with a target satellite. In this re-duced model it is found that the Jacobian and inertia matrices can be considered as an extension of those of a free-flying space robot. Since control of the base attitude rather than its translation is preferred in certain cases, a second reduced model is obtained by eliminating the base linear motion dynamics. For the purpose of the controller development, a third reduced-order dynamical model is then obtained by finding a common solution of all constraints using the concept of orthogonal projection matrices. The objective of this approach is to design a controller to track motion trajectory while regulating the force interaction between the space robot and the target satellite. Many space missions can benefit from such a modeling system, for example, autonomous docking of satellites, rescuing satellites, and satellite servicing, where it is vital to limit the con-tact force during the robotic operation. Moreover, Inverse dynamics and adaptive inverse dynamics control-lers are designed to achieve the control objectives. Both controllers are found to be effective to meet the specifications and to overcome the un-actuation of the target satellite. Finally, simulation is demonstrated by to verify the analytical results.展开更多
Previous studies have confirmed that both honeybee and Drosophila are capable of learning and memory. This study aimed to investigate whether the house fly （Aldrichina grahami）, with strong instincts to adapt their ...Previous studies have confirmed that both honeybee and Drosophila are capable of learning and memory. This study aimed to investigate whether the house fly （Aldrichina grahami）, with strong instincts to adapt their living environment, have the learning ability to associate odor stimulus to avoid electric shock in free flying state using a device developed by the authors. The result showed the learning ability ofA. grahami at the electric shock voltages of 5 V, 25 V and 45 V AC. When 60 V was used, the flies were frequently injured. Our results indicate that A. grahami is a good model to study the neural mechanism of learning and memory. The paradigm in this study has some advantages that can be used in future studies of free insects.展开更多
Although many studies on the fishery biology of jumbo flying squid, Dosidicus gigas, have been conducted in the coastal areas within Exclusive Economic Zones （EEZs） of various countries due to its commercial and eco...Although many studies on the fishery biology of jumbo flying squid, Dosidicus gigas, have been conducted in the coastal areas within Exclusive Economic Zones （EEZs） of various countries due to its commercial and ecological importance, limited biological information is available from waters outside these EEZs. In this paper, we examined D. gigas fishery biology from waters outside Chilean, Peruvian and Costa Rican EEZs, based on the fishery data collected by Chinese jigging vessels during 2006 to 2010. The dominant mantle lengths olD. gigas were 350-450 mm, 250-400 mm and 250-350 mm outside Chilean, Peruvian and Costa Rican EEZs, respectively. Size structure analysis show that a medium-sized group existed mostly in the waters outside the Chilean and Peruvian EEZs, whereas a small-sized group occurred mainly in the waters outside the Costa Rican EEZ. The longevity of the squid outside the Costa Rican EEZ was less than 10 months, while most of those outside Chilean and Peruvian EEZs were about 1-1.5 years and very few large individuals were 1.5-2 years old. A higher percentage of mature individuals existed outside Costa Rican EEZ implying the region as a potential spawning ground, while lower proportions of mature squid outside the Peruvian and Chilean EEZs indicated that spawning may be occurring outside our study area. Spatial differences in sizes at maturity of the squid are thought to be result from different environmental factors especially different temperature and nutrition among the three areas. Stomach-content analysis showed that cannibalism was important in the diet of D. gigas. Stress generated by jigging may increase the incidence of cannibalism.展开更多
In this paper, the relative orbital configurations of satellites in formation flying with non-perturbation and J<SUB>2</SUB> perturbation are studied, and an orbital elements method is proposed to obtain t...In this paper, the relative orbital configurations of satellites in formation flying with non-perturbation and J<SUB>2</SUB> perturbation are studied, and an orbital elements method is proposed to obtain the relative orbital configurations of satellites in formation. Firstly, under the condition of non-perturbation, we obtain many shapes of relative orbital configurations when the semi-major axes of satellites are equal. These shapes can be lines, ellipses or distorted closed curves. Secondly, on the basis of the analysis of J<SUB>2</SUB> effect on relative orbital configurations, we find out that J<SUB>2</SUB> effect can induce two kinds of changes of relative orbital configurations. They are distortion and drifting, respectively. In addition, when J<SUB>2</SUB> perturbation is concerned, we also find that the semi-major axes of the leading and following satellites should not be the same exactly in order to decrease the J<SUB>2</SUB> effect. The relationship of relative orbital elements and J<SUB>2</SUB> effect is obtained through simulations. Finally, the minimum relation perturbation conditions are established in order to reduce the influence of the J<SUB>2</SUB> effect. The results show that the minimum relation perturbation conditions can reduce the J<SUB>2</SUB> effect significantly when the orbital element differences are small enough, and they can become rules for the design of satellite formation flying.展开更多
Experimental investigation of aerodynamic control on a 35° swept flying wing by means of nanosecond dielectric barrier discharge （NS-DBD） plasma was carried out at subsonic flow speed of 20-40 m/s, correspondin...Experimental investigation of aerodynamic control on a 35° swept flying wing by means of nanosecond dielectric barrier discharge （NS-DBD） plasma was carried out at subsonic flow speed of 20-40 m/s, corresponding to Reynolds number of 3.1 × 10^5-6.2× 10^5. In control condition, the plasma actuator was installed symmetrically on the leading edge of the wing. Lift coefficient, drag coefficient, lift-to-drag ratio and pitching moment coefficient were tested with and without control for a range of angles of attack. The tested results indicate that an increase of 14.5% in maximum lift coefficient, a decrease of 34.2% in drag coefficient, an increase of 22.4% in maximum lift-to-drag ratio and an increase of 2° at stall angle of attack could be achieved compared with the baseline case. The effects of pulsed frequency, amplitude and chord Reynolds number were also investigated. And the results revealed that control efficiency demonstrated strong dependence on pulsed fre- quency. Moreover, the results of pitching moment coefficient indicated that the breakdown of lead- ing edge vortices could be delayed by plasma actuator at low pulsed frequencies.展开更多
This paper investigates the problem of Spacecraft Formation-Containment Flying Control(SFCFC)when the desired translational velocity is time-varying.In SFCFC problem,there are multiple leader spacecraft and multiple f...This paper investigates the problem of Spacecraft Formation-Containment Flying Control(SFCFC)when the desired translational velocity is time-varying.In SFCFC problem,there are multiple leader spacecraft and multiple follower spacecraft and SFCFC can be divided into leader spacecraft’s formation control and follower spacecraft’s containment control.First,under the condition that only a part of leader spacecraft can have access to the desired time-varying translational velocity,a velocity estimator is designed for each leader spacecraft.Secondly,based on the estimated translational velocity,a distributed formation control algorithm is designed for leader spacecraft to achieve the desired formation and move with the desired translational velocity simultaneously.Then,to ensure all follower spacecraft converge to the convex hull formed by the leader spacecraft,a distributed containment control algorithm is designed for follower spacecraft.Moreover,to reduce the dependence of the designed control algorithms on the graph information and increase system robustness,the control gains are changing adaptively and the parametric uncertainties are handled,respectively.Finally,simulation results are provided to illustrate the effectiveness of the theoretical results.展开更多
This work deals with the development of a decentralized optimal control algorithm, along with a robust observer,for the relative motion control of spacecraft in leader-follower based formation. An adaptive gain higher...This work deals with the development of a decentralized optimal control algorithm, along with a robust observer,for the relative motion control of spacecraft in leader-follower based formation. An adaptive gain higher order sliding mode observer has been proposed to estimate the velocity as well as unmeasured disturbances from the noisy position measurements.A differentiator structure containing the Lipschitz constant and Lebesgue measurable control input, is utilized for obtaining the estimates. Adaptive tuning algorithms are derived based on Lyapunov stability theory, for updating the observer gains,which will give enough flexibility in the choice of initial estimates.Moreover, it may help to cope with unexpected state jerks. The trajectory tracking problem is formulated as a finite horizon optimal control problem, which is solved online. The control constraints are incorporated by using a nonquadratic performance functional. An adaptive update law has been derived for tuning the step size in the optimization algorithm, which may help to improve the convergence speed. Moreover, it is an attractive alternative to the heuristic choice of step size for diverse operating conditions. The disturbance as well as state estimates from the higher order sliding mode observer are utilized by the plant output prediction model, which will improve the overall performance of the controller. The nonlinear dynamics defined in leader fixed Euler-Hill frame has been considered for the present work and the reference trajectories are generated using Hill-Clohessy-Wiltshire equations of unperturbed motion. The simulation results based on rigorous perturbation analysis are presented to confirm the robustness of the proposed approach.展开更多
In this paper,the fixed-time stability of spacecraft formation reconfiguration(position tracking)is studied.Firstly,a novel nonsingular terminal sliding mode surface is designed and based on which a fixed-time coordin...In this paper,the fixed-time stability of spacecraft formation reconfiguration(position tracking)is studied.Firstly,a novel nonsingular terminal sliding mode surface is designed and based on which a fixed-time coordinated controller is designed to keep the closed-loop system states have a finite settling time bounded by some predefined constants.Secondly,another nonsingular terminal sliding mode surface is designed by combining the artificial potential function and the aforementioned sliding surface,which meets the mutual distance constraint during transition process among spacecraft when it is bounded.Then another coordinated controller with fixed-time observer considering mutual distance constraint is presented,which guarantees the closed-loop system states stable also in bounded settling time.Finally,simulation results are shown to validate the correctness of the proposed theorems.It is worth mentioning that the control schemes also work even though there is a properly limit on the control input.展开更多
文摘More than seventy years before airplanes were invented,a twelve⁃year⁃old girl named Ada Lovelace dreamed of flying.She studied birds and experimented with materials to make wings,even writing a guide called Flyology.But her curiosity didnt stop there.
基金supported by the Natural Science Foundation of China(No.52236001)The support from Research Grants Council of Hong Kong,China(No.CityU 15218820)was also appreciated。
文摘The evaporation behaviors are crucial for the flame location estimation in liquid rocketengines.This work,for the first time,experimentally reports the sub-millimeter droplet evaporationcharacteristics of the corrosive dinitrogen tetroxide(NTO,one prevailing hypergolic oxidizer)athigh ambient pressure up to 4.5 MPa.An in-house corrosion-resistant droplet generator is usedto generate isolated flying droplets of sub-millimeter size,which are then exposed in a gas environ-ment with temperatures between 1010 K and 1210 K and pressures in the range between 2.0 MPaand 4.5 MPa,provided by an optical rapid compression machine.Parallelly,a theoretical modelconsidering both the droplet ambient convection and the NTO dissociation is developed.Resultsindicate that firstly,the present theoretical model that considers the transient droplet-ambient con-vection as well as the temperature and pressure dependent rate of dissociation shows good agree-ment with the experimentally observed droplet lifetime.In addition,the flying droplets velocityregress gradually due to momentum exchange with the ambient,which is more prominent at higherpressure.The evaporation caused droplet size reduction is consistent with the classical D^(2)-law pre-diction,in the present temperature and pressure range.Finally,higher temperature and pressureaccelerate the evaporation and an empirical correlation for the temperature and pressure dependentevaporation rate constant is proposed,which shows good agreement with experiment and simula-tion results.
文摘The flying-wing aircraft has excellent aerodynamic efficiency and stealth performance.However,due to the lack of tails,the flying-wing aircraft has a serious attitude control problem.In this paper,the effective flow control strategy of three-axis control is proposed by using continuous jets for a flapless flying-wing aircraft.The wind tunnel test of two kinds of flying-wing models,namely one flow control model and one mechanical control model,is conducted,and the control effect is analyzed and compared.By simultaneous blowing of the circulation control actuators inboard and differential blowing of the circulation control actuators outboard,the pitch and roll controls are achieved,respectively.It also has an effective control effect at very large angles of attack where the conventional control surface fails.A linear relationship is found between the increment of the controlled aerodynamic force/moment coefficient and the momentum coefficient for circulation control actuators.Moreover,to resolve the difficulty in yaw control,a novel wingtip jet is proposed based on the concept of the all-moving tip and compared with apex jet and circulation control jet.It is found that the wingtip jet is the most efficient actuator,followed by the simultaneous-blowing circulation control jet.Therefore,based on the research above,two optimized fluidic control configurations are proposed.One employs circulation control jet and wingtip jet,and the other is completely dependent on circulation control jet.Finally,the flow control mechanism of circulation control is discussed.Circulation control significantly accelerates the flow on the upper surface of the airfoil in attached flow and reduces the flow separation region in separated flow,leading to aerodynamic performance improvement.These results provide an important theoretic basis for the flapless flight control of flying-wing aircraft.
基金College Student Innovation Training Program Project(S202410225147)。
文摘To address the challenges of long commuting times,traffic congestion,high energy consumption,and emissions in inter-city travel,a new type of flying coach has been developed.This innovation aims to significantly shorten inter-city commuting times,enhance travel efficiency,and simultaneously reduce energy consumption and emissions.The flying coach integrates rail power supply technology,an intelligent operating system,and advanced new materials,comprising a catenary power supply guide rod and various sensor components.Based on analysis of traditional aircraft design principles,the research team simulated the design of the rail-powered flying coach using software such as AutoCAD and SolidWorks for three-dimensional modeling.The analysis results indicate that,compared to traditional aircraft and rail trains,the design of the new flying coach reduces its overall weight while maintaining carrying capacity,thereby improving commuting efficiency and environmental performance.This development lays a solid foundation for creating a greener,more efficient,and convenient inter-city transportation network.
基金supported by the National Laboratory of Space Intelligent Control(No.HTKJ2023KL502007)the Chinese Government Scholarship(CSC)。
文摘In response to the need for a supportive on-orbit platform for future Mars exploration missions,this paper proposes the design and implementation of an autonomous spacecraft formation flying system near the Martian synchronous orbit using fuzzy learning-based intelligent control.A detailed analysis of spacecraft relative motion in the Mars environment is conducted,deducing the necessary conditions to reach the Martian synchronous orbit constraints.The modified Clohessy-Wiltshire(C-W)equation with Martian J_(2)(Oblateness index)perturbation is used as a reference to design a fuzzy learning-based intelligent and robust nonlinear control approach,which helps to autonomously track the desired formation configuration and stabilizes it.An introduction to spacecraft propulsion mechanisms is provided to analyze the feasibility of using electrical thrusters for spacecraft formation configuration tracking and stabilization in Martian synchronous orbits.The simulations show the effectiveness of the proposed control system for long-term on-orbit operations and reveal its reliability for designing intelligent deep-space formation flying configurations,such as an autonomous Mars observatory,a Martian telescope,or an interferometer.
基金co-supported by the National Natural Science Foundation of China(Nos.52272408,U21B2008)the Guangdong Basic and Applied Basic Research Foundation,China(No.2023B1515120018)。
文摘This paper investigates the configuration design associated with boundary-constrained swarm flying.An analytic swarm configuration is identified to ensure the passive safety between each pair of spacecraft in the radial-cross-track plane.For the first time,this work derives the explicit configurable spacecraft amount to clarify the configuration's accommodation capacity while considering the maximum inter-spacecraft separation constraint.For larger-scale design problem that involves hundreds of spacecraft,this paper proposes an optimization framework that integrates a Relative Orbit Element(ROE)affine transformation operation and successional convex optimization.The framework establishes a multi-subcluster swarm structure,allowing decoupling the maintenance issues of each subcluster.Compared with previous design methods,it ensures that the computational cost for constraints verification only scales linearly with the swarm size,while also preserving the configuration optimization capacities.Numerical simulations demonstrate that the proposed analytic configuration strictly meets the design constraints.It is also shown that the proposed framework reduces the handled constraint amount by two orders compared with direct optimization,while achieving a remarkable swarm safety enhancement based on the existing analytic configuration.
基金co-supported by the Fundamental Research Funds for the Central Universities of China(No.YWF-23-SDHK-L-005)the Aeronautical Science Foundation of China(Nos.20220048051001,20230013051002)+2 种基金National Key Laboratory of Science and Technology on Rotorcraft AeromechanicsChina(Nos.61422202205,61422202106)the 1912Project,China。
文摘Tiltrotors have three flight modes that pose control problems and quality defects during the conversion process.To address this,a novel flying qualities-based time-varying stability augmentation system is designed to achieve multi-mode,nonlinear,and time-varying stability.The system integrates a nonlinear time-varying control law with the flying qualities requirements for all three flight modes.It consists of an inner and outer loop control framework,where the control law in the inner loop is designed based on the Lyapunov theorem of stability.The reference models in the outer loop are derived from the flying qualities criteria to meet level one flying qualities requirements.To evaluate the conversion process,a time-varying flying qualities evaluation method is developed,which includes the conversion path,pilot model,and time-varying flying qualities index.The proposed time-varying stability augmentation control system is then tested through simulation during the conversion process.A pilot-aircraft closed-loop system is established for conducting experiments.Comparison between simulation results and pilot-in-loop experiment results demonstrates the effectiveness of the proposed control system.Furthermore,it proves that the evaluation method is suitable for analyzing time-varying systems.This research can be valuable in designing and evaluating stability augmentation controls for strongly time-varying systems.
文摘Herein,a control method based on the optimal energy efficiency of a hydraulic quadruped robot was proposed,which not only realizes the optimal energy efficiency of flying trot gait but also ensures the stability of high-speed movement.Concretely,the energy consumption per unit distance was adopted as the energy efficiency evaluation index based on the constant pressure oil supply characteristics of the hydraulic system,and the global optimization algorithm was adopted to solve the optimal parameters.Afterward,the gait parameters that affect the energy efficiency of quadruped were analyzed and the mapping relationship between each parameter and energy efficiency was captured,so as to select the optimum combination of energy efficiency parameters,which is significant to improve endurance capability.Furthermore,to ensure the stability of the high-speed flying trot gait motion of the hydraulic quadruped robot,the active compliance control strategy was employed.Lastly,the proposed method was successfully verified by simulations and experiments.The experimental results reveal that the flying trot gait of the hydraulic quadruped robot can be stably controlled at a speed of 2.2 m/s.
基金support from the Ningxia Natural Science Foundation Project(2023AAC03361).
文摘The flying foxes optimization(FFO)algorithm,as a newly introduced metaheuristic algorithm,is inspired by the survival tactics of flying foxes in heat wave environments.FFO preferentially selects the best-performing individuals.This tendency will cause the newly generated solution to remain closely tied to the candidate optimal in the search area.To address this issue,the paper introduces an opposition-based learning-based search mechanism for FFO algorithm(IFFO).Firstly,this paper introduces niching techniques to improve the survival list method,which not only focuses on the adaptability of individuals but also considers the population’s crowding degree to enhance the global search capability.Secondly,an initialization strategy of opposition-based learning is used to perturb the initial population and elevate its quality.Finally,to verify the superiority of the improved search mechanism,IFFO,FFO and the cutting-edge metaheuristic algorithms are compared and analyzed using a set of test functions.The results prove that compared with other algorithms,IFFO is characterized by its rapid convergence,precise results and robust stability.
文摘The current academic research on the Dian Shi Zhai Pictorial founded in 1884 has been perfected,but there is very little research on the Flying Shadow Pavilion Pictorial,which can be said to be derived from Dian Shi Zhai Pictorial terms of both content and form,and which was founded by the Haiist painter Wu Youru in 1890 in order to reward the increasing number of admirers,but it is still in the initial stage.Flying Shadow Pavilion Pictorial consisted of four parts:pictures of ladies in Shanghai costumes,news about current affairs,pictures of animals,and compilations of women,each of which was accompanied by the then popular notebooks,which were popular at the time among the then readers because of the matching of pictures with text and the mixing of narratives and discussions.This paper takes Flying Shadow Pavilion Pictorial as the main object,summarizes the existing literature about Flying Shadow Pavilion Pictorial,points out the deficiencies of the current research on this basis,and points out the development trend of Flying Shadow Pavilion Pictorial in the future research.
基金Aeronautical Science Foundation of China (2006ZA51004)Fanzhou Foundation of China(20100506)
文摘During the process of aircraft design, the mathematical model of pilot control behavior characteristics is always used to predict aircraft flying qualities （FQ）. This is one of the important methods to avoid pilot-aircraft adverse coupling. In order to study the FQ criterion based on closed-loop pilot-aircraft systems, first, an experimental database is built, which includes 40 aircraft dynamics configurations and the corresponding flight simulation results. Second, the mathematical pilot models with a set of different aircraft configurations are obtained by this experimental database. Then, two FQ criteria, Neal-Smith criterion and Moscow Aviation Institute （MAI） criterion, are analyzed. And the relationship between the FQ level evaluated by actual pilot and the parameters of closed-loop pilot-aircraft systems is studied. Finally, an improved criterion of aircraft FQ is built based on the above two criteria. This new criterion is further used to predict FQ for four new aircraft dynamics configurations, and the prediction results verify its accuracy and practicability.
文摘In this paper a unified control-oriented modeling approach is proposed to deal with the kinematics, linear and angular momentum, contact constraints and dynamics of a free-flying space robot interacting with a target satellite. This developed approach combines the dynamics of both systems in one structure along with holonomic and nonholonomic constraints in a single framework. Furthermore, this modeling allows consid-ering the generalized contact forces between the space robot end-effecter and the target satellite as internal forces rather than external forces. As a result of this approach, linear and angular momentum will form holonomic and nonholonomic constraints, respectively. Meanwhile, restricting the motion of the space robot end-effector on the surface of the target satellite will impose geometric constraints. The proposed momentum of the combined system under consideration is a generalization of the momentum model of a free-flying space robot. Based on this unified model, three reduced models are developed. The first reduced dynamics can be considered as a generalization of a free-flying robot without contact with a target satellite. In this re-duced model it is found that the Jacobian and inertia matrices can be considered as an extension of those of a free-flying space robot. Since control of the base attitude rather than its translation is preferred in certain cases, a second reduced model is obtained by eliminating the base linear motion dynamics. For the purpose of the controller development, a third reduced-order dynamical model is then obtained by finding a common solution of all constraints using the concept of orthogonal projection matrices. The objective of this approach is to design a controller to track motion trajectory while regulating the force interaction between the space robot and the target satellite. Many space missions can benefit from such a modeling system, for example, autonomous docking of satellites, rescuing satellites, and satellite servicing, where it is vital to limit the con-tact force during the robotic operation. Moreover, Inverse dynamics and adaptive inverse dynamics control-lers are designed to achieve the control objectives. Both controllers are found to be effective to meet the specifications and to overcome the un-actuation of the target satellite. Finally, simulation is demonstrated by to verify the analytical results.
文摘Previous studies have confirmed that both honeybee and Drosophila are capable of learning and memory. This study aimed to investigate whether the house fly （Aldrichina grahami）, with strong instincts to adapt their living environment, have the learning ability to associate odor stimulus to avoid electric shock in free flying state using a device developed by the authors. The result showed the learning ability ofA. grahami at the electric shock voltages of 5 V, 25 V and 45 V AC. When 60 V was used, the flies were frequently injured. Our results indicate that A. grahami is a good model to study the neural mechanism of learning and memory. The paradigm in this study has some advantages that can be used in future studies of free insects.
基金Supported by the National Natural Science Foundation of China(No.NSFC41276156)Innovation Program of Shanghai Municipal Education Commission(No.13YE091)+5 种基金Industrialization Project of National Development and Reform Commission(No.2159999)Project of Shanghai Science and Technology Commission(No.12231203900)National High Technology Research and Development Program of China(863 Program)(No.2012AA092303)Shanghai Leading Academic Discipline Project(Fisheries Discipline)National Distant-Water Fisheries Engineering Research Centerthe Scientific Observing and Experimental Station of Oceanic Fishery Resources,Ministry of Agriculture
文摘Although many studies on the fishery biology of jumbo flying squid, Dosidicus gigas, have been conducted in the coastal areas within Exclusive Economic Zones （EEZs） of various countries due to its commercial and ecological importance, limited biological information is available from waters outside these EEZs. In this paper, we examined D. gigas fishery biology from waters outside Chilean, Peruvian and Costa Rican EEZs, based on the fishery data collected by Chinese jigging vessels during 2006 to 2010. The dominant mantle lengths olD. gigas were 350-450 mm, 250-400 mm and 250-350 mm outside Chilean, Peruvian and Costa Rican EEZs, respectively. Size structure analysis show that a medium-sized group existed mostly in the waters outside the Chilean and Peruvian EEZs, whereas a small-sized group occurred mainly in the waters outside the Costa Rican EEZ. The longevity of the squid outside the Costa Rican EEZ was less than 10 months, while most of those outside Chilean and Peruvian EEZs were about 1-1.5 years and very few large individuals were 1.5-2 years old. A higher percentage of mature individuals existed outside Costa Rican EEZ implying the region as a potential spawning ground, while lower proportions of mature squid outside the Peruvian and Chilean EEZs indicated that spawning may be occurring outside our study area. Spatial differences in sizes at maturity of the squid are thought to be result from different environmental factors especially different temperature and nutrition among the three areas. Stomach-content analysis showed that cannibalism was important in the diet of D. gigas. Stress generated by jigging may increase the incidence of cannibalism.
基金The project supported by the National Natural Science Foundation of China(10202008)Specialized Research Fund for the Doctoral Program of Higher Education(20020003024)
文摘In this paper, the relative orbital configurations of satellites in formation flying with non-perturbation and J<SUB>2</SUB> perturbation are studied, and an orbital elements method is proposed to obtain the relative orbital configurations of satellites in formation. Firstly, under the condition of non-perturbation, we obtain many shapes of relative orbital configurations when the semi-major axes of satellites are equal. These shapes can be lines, ellipses or distorted closed curves. Secondly, on the basis of the analysis of J<SUB>2</SUB> effect on relative orbital configurations, we find out that J<SUB>2</SUB> effect can induce two kinds of changes of relative orbital configurations. They are distortion and drifting, respectively. In addition, when J<SUB>2</SUB> perturbation is concerned, we also find that the semi-major axes of the leading and following satellites should not be the same exactly in order to decrease the J<SUB>2</SUB> effect. The relationship of relative orbital elements and J<SUB>2</SUB> effect is obtained through simulations. Finally, the minimum relation perturbation conditions are established in order to reduce the influence of the J<SUB>2</SUB> effect. The results show that the minimum relation perturbation conditions can reduce the J<SUB>2</SUB> effect significantly when the orbital element differences are small enough, and they can become rules for the design of satellite formation flying.
基金supported by the National Natural Science Foundation of China – China (Nos. 51276197, 51207169 and 51336011)
文摘Experimental investigation of aerodynamic control on a 35° swept flying wing by means of nanosecond dielectric barrier discharge （NS-DBD） plasma was carried out at subsonic flow speed of 20-40 m/s, corresponding to Reynolds number of 3.1 × 10^5-6.2× 10^5. In control condition, the plasma actuator was installed symmetrically on the leading edge of the wing. Lift coefficient, drag coefficient, lift-to-drag ratio and pitching moment coefficient were tested with and without control for a range of angles of attack. The tested results indicate that an increase of 14.5% in maximum lift coefficient, a decrease of 34.2% in drag coefficient, an increase of 22.4% in maximum lift-to-drag ratio and an increase of 2° at stall angle of attack could be achieved compared with the baseline case. The effects of pulsed frequency, amplitude and chord Reynolds number were also investigated. And the results revealed that control efficiency demonstrated strong dependence on pulsed fre- quency. Moreover, the results of pitching moment coefficient indicated that the breakdown of lead- ing edge vortices could be delayed by plasma actuator at low pulsed frequencies.
基金supported by the National Natural Science Foundation of China(Nos.61876050,61673135,61603114).
文摘This paper investigates the problem of Spacecraft Formation-Containment Flying Control(SFCFC)when the desired translational velocity is time-varying.In SFCFC problem,there are multiple leader spacecraft and multiple follower spacecraft and SFCFC can be divided into leader spacecraft’s formation control and follower spacecraft’s containment control.First,under the condition that only a part of leader spacecraft can have access to the desired time-varying translational velocity,a velocity estimator is designed for each leader spacecraft.Secondly,based on the estimated translational velocity,a distributed formation control algorithm is designed for leader spacecraft to achieve the desired formation and move with the desired translational velocity simultaneously.Then,to ensure all follower spacecraft converge to the convex hull formed by the leader spacecraft,a distributed containment control algorithm is designed for follower spacecraft.Moreover,to reduce the dependence of the designed control algorithms on the graph information and increase system robustness,the control gains are changing adaptively and the parametric uncertainties are handled,respectively.Finally,simulation results are provided to illustrate the effectiveness of the theoretical results.
文摘This work deals with the development of a decentralized optimal control algorithm, along with a robust observer,for the relative motion control of spacecraft in leader-follower based formation. An adaptive gain higher order sliding mode observer has been proposed to estimate the velocity as well as unmeasured disturbances from the noisy position measurements.A differentiator structure containing the Lipschitz constant and Lebesgue measurable control input, is utilized for obtaining the estimates. Adaptive tuning algorithms are derived based on Lyapunov stability theory, for updating the observer gains,which will give enough flexibility in the choice of initial estimates.Moreover, it may help to cope with unexpected state jerks. The trajectory tracking problem is formulated as a finite horizon optimal control problem, which is solved online. The control constraints are incorporated by using a nonquadratic performance functional. An adaptive update law has been derived for tuning the step size in the optimization algorithm, which may help to improve the convergence speed. Moreover, it is an attractive alternative to the heuristic choice of step size for diverse operating conditions. The disturbance as well as state estimates from the higher order sliding mode observer are utilized by the plant output prediction model, which will improve the overall performance of the controller. The nonlinear dynamics defined in leader fixed Euler-Hill frame has been considered for the present work and the reference trajectories are generated using Hill-Clohessy-Wiltshire equations of unperturbed motion. The simulation results based on rigorous perturbation analysis are presented to confirm the robustness of the proposed approach.
基金supported by the Major Program of Natural Science Foundation of China(No.61690210)the Science Fund for Excellent Young Scholars of Heilongjiang Province,China(No.YQ2020F007)National Natural Science Foundation of China(No.6191101340)。
文摘In this paper,the fixed-time stability of spacecraft formation reconfiguration(position tracking)is studied.Firstly,a novel nonsingular terminal sliding mode surface is designed and based on which a fixed-time coordinated controller is designed to keep the closed-loop system states have a finite settling time bounded by some predefined constants.Secondly,another nonsingular terminal sliding mode surface is designed by combining the artificial potential function and the aforementioned sliding surface,which meets the mutual distance constraint during transition process among spacecraft when it is bounded.Then another coordinated controller with fixed-time observer considering mutual distance constraint is presented,which guarantees the closed-loop system states stable also in bounded settling time.Finally,simulation results are shown to validate the correctness of the proposed theorems.It is worth mentioning that the control schemes also work even though there is a properly limit on the control input.
