Stratospheric airships are lighter-than-air vehicles capable of continuous flying for months.The energy balance of the airship is the key to long-duration flights.The stratospheric airship is entirely powered by the s...Stratospheric airships are lighter-than-air vehicles capable of continuous flying for months.The energy balance of the airship is the key to long-duration flights.The stratospheric airship is entirely powered by the solar array.It is necessary to accurately predict the output power of the array for any flight state.Because of the uneven solar radiation received by the solar array,the traditional model based on components has a slow simulation speed.In this study,a data-driven surrogate modeling approach for prediction the output power of the solar array is proposed.The surrogate model is trained using the samples obtained from the high-accuracy simulation model.By using the input parameter preprocessor,the accuracy of the surrogate model in predicting the output power of the solar array is improved to 98.65%.In addition,the predictive speed of the surrogate model is ten million times faster than the traditional simulation model.Finally,the surrogate model is used to predict the energy balance of stratospheric airships flying throughout the year under actual global wind fields.展开更多
This paper studies the tracking control problem for stratospheric airships with userspecified performance.Dealing with the infinite gain phenomenon in the prescribed-time stability,a new stability criterion with bound...This paper studies the tracking control problem for stratospheric airships with userspecified performance.Dealing with the infinite gain phenomenon in the prescribed-time stability,a new stability criterion with bounded gain is proposed by using a new time-varying scaling function.Moreover,a same-side performance function and a novel barrier Lyapunov function are incorporated into the control algorithm,which can compress the feasible domain of tracking error to minimize the overshoot and solve the difficult in tracking error not converging to zero simultaneously.The proposed scheme guarantees the airship capable of operating autonomously with satisfactory transient performance and tracking accuracy,where the performance parameters can be designed artificially and link to the physical process directly.Finally,the effectiveness of the proposed control scheme is verified by theoretical analysis and numerical simulation.展开更多
The stratospheric airship is affected by harsh conditions in the stratosphere environment.To ensure the safety of the airship,it is necessary to detect the material state of the airship envelope.Since digital image co...The stratospheric airship is affected by harsh conditions in the stratosphere environment.To ensure the safety of the airship,it is necessary to detect the material state of the airship envelope.Since digital image correlation possesses non-contact strain measurement ability,this paper explores the infuence of different shapes of the subset on measurement accuracy.Through the results,it is found that increasing the aspect ratio of subsets can improve the strain accuracy measured in the c-direction,and reducing the aspect ratio can improve the strain accuracy measured in the y-direction.This trend becomes more obvious as the strain increases.Based on this discovery,a subset adaptive algorithm is proposed.The feasibility of the algorithm is verified by experiments,and the precision of strain measurement can be effectively improved by adjusting the threshold value.Therefore,the algorithm can be utilized to increase the measurement accuracy in the larger strain direction without changing the size of the subset.展开更多
The robotic airship can provide a promising aerostatic platform for many potential applications.These applications require a precise autonomous trajectory tracking control for airship.Airship has a nonlinear and uncer...The robotic airship can provide a promising aerostatic platform for many potential applications.These applications require a precise autonomous trajectory tracking control for airship.Airship has a nonlinear and uncertain dynamics.It is prone to wind disturbances that offer a challenge for a trajectory tracking control design.This paper addresses the airship trajectory tracking problem having time varying reference path.A lumped parameter estimation approach under model uncertainties and wind disturbances is opted against distributed parameters.It uses extended Kalman filter(EKF)for uncertainty and disturbance estimation.The estimated parameters are used by sliding mode controller(SMC)for ultimate control of airship trajectory tracking.This comprehensive algorithm,EKF based SMC(ESMC),is used as a robust solution to track airship trajectory.The proposed estimator provides the estimates of wind disturbances as well as model uncertainty due to the mass matrix variations and aerodynamic model inaccuracies.The stability and convergence of the proposed method are investigated using the Lyapunov stability analysis.The simulation results show that the proposed method efficiently tracks the desired trajectory.The method solves the stability,convergence,and chattering problem of SMC under model uncertainties and wind disturbances.展开更多
Stratospheric airships are long-endurance aerostats and have broad applications.All of the energy required for their operation is obtained from solar radiation,which makes accurate calculation of the energy output fro...Stratospheric airships are long-endurance aerostats and have broad applications.All of the energy required for their operation is obtained from solar radiation,which makes accurate calculation of the energy output from the solar array crucial to the design and flight planning of the airships.However,the status of each photovoltaic module in the solar array may differ due to the airship curvature,resulting in mismatch losses and lowered output power,which has not been widely studied.In this paper,an irradiation model and a thermal model are established based on the actual arrangement of the modules.The output power model is established considering the non-uniform radiation in the array.The mismatch losses of the array are analyzed under different flight conditions.The output power of the solar array is decreased by up to 31.6%compared to the ideal state.Moreover,the proportion of mismatch losses increases with latitude,but the maximum mismatch loss power occurs at mid-latitudes.Then,an array reconfiguration method is proposed based on the irradiance dispersion index and position dispersion index.The reconfigured array increases output power by 11.5%and can maintain energy balance in continuous flight.The results can be used to correct the overestimation of the output power during the airship design or to guide the configuration of the solar array.展开更多
The robotic airship is one of the most unique and promising green aircraft,however,as a“lighter-than-air aircraft”and“thermal aircraft”,its long-endurance flight has great difficulties in decreasing drag and contr...The robotic airship is one of the most unique and promising green aircraft,however,as a“lighter-than-air aircraft”and“thermal aircraft”,its long-endurance flight has great difficulties in decreasing drag and controlling buoyancy and pressure under thermal effects.In this work,we reported a robotic airship inspired by the Physalia physalis,imitating its morphology,physiological structure,and biological behaviors.The hull is designed by imitating the morphology of the Physalia physalis,and the gasbags including a helium balloon,two ballonets,and a thermoregulation gasbag are designed by imitating the physiological structure and biological behaviors of the pneumatophore,bladder,and gland of the Physalia physalis,respectively.Experimental results show that the bionic airship has an increase of about 40%in lift-to-drag and decreases the pressure in helium balloon by 47.5%under thermal effects,and has better aerodynamic performances and thermoregulation performances than conventional airships.展开更多
The current study focuses on the motion-pressure coupled control for a multicapsule stratospheric airship and transforms the path-tracking and heading-hold control of airships into guidance tracking with a time-varyin...The current study focuses on the motion-pressure coupled control for a multicapsule stratospheric airship and transforms the path-tracking and heading-hold control of airships into guidance tracking with a time-varying weighted sum of longitudinal and lateral velocities by the definition of compound speed.Herein,an improved nonlinear predictive control method is provided to reduce the control energy consumption by the rolling optimization of controller parameters based on finite time intervals,ensuring infinite-time path-tracking tasks.Simultaneously,combined with the proposed cyclic regulation process of safe pressure between internal and external capsules,this study can fully reflect the force-thermal coupled rule of airships under the actions of atmospheric environment and maneuvering force,while evaluating the long-endurance capability of airships under the conditions of safe superheating and overpressure.The effectiveness of the motionpressure coupled controller was verified through numerical simulations,which can overcome the influence of environmental wind and achieve a tracking effect for the desired cruise path and compound speed.The airspeed provided during the cyclic circadian time caused the maximum superheating of the helium controlled within 30C.The helium in the internal and external capsules achieved circadian regulation.The equivalent micropore diameter of the capsule of 5 mm can achieve 55 days of long-endurance flight.The controller satisfies the requirements of cruise-flight application modes for multicapsule stratospheric airships with important engineering value.展开更多
The voluminous stratospheric non-rigid airship is very sensitive to the external thermal environment.The temperature change of internal gas caused by the variation in the external ther-mal environment and wind speed w...The voluminous stratospheric non-rigid airship is very sensitive to the external thermal environment.The temperature change of internal gas caused by the variation in the external ther-mal environment and wind speed will lead to a change in the shape and buoyancy of the airship,thereby affecting its flight control.The traditional static analysis method is difficult to accurately reflect this fuid-thermal-structural coupling process.In this paper,the iterative analysis method was established for the fluid-thermal-structural coupling effect of stratospheric non-rigid airship based on the models of fluid,thermal,and structural deformation.Considering the load such as the internal thermal effect and external flow field of the airship,the simulation of the thermo-induced structural deformation effect was conducted using Fluent and Abaqus software.The influ-ence of local time and external wind speed on the structural deformation,volume,and equilibrium altitude of the airship was analyzed.The results demonstrate that,at low wind speed,the influence of aerodynamic pressure on the deformation of the airship is negligible.However,a great amount of heat is carried away by the wind,then the structural deformation caused by internal and external pressure difference is alleviated and the equilibrium altitude of the airship change obviously.This can serve as a guideline for the design and flight test of the long-endurance stratospheric non-rigid airship.展开更多
Intermodal competition changes with changes in technology, economics, and environmental concerns. Trucks and airships are generally considered not to be competitors, but this depends on the distance of haul. The tonne...Intermodal competition changes with changes in technology, economics, and environmental concerns. Trucks and airships are generally considered not to be competitors, but this depends on the distance of haul. The tonne-kilometer cost of trucking rises much more quickly with distance than it does the cost of a cargo airship. At some distance, the two modes are direct substitutes. The costs of the Mexico-Canada refrigerated truck supply chain are compared with the costs of a 100t-lift, electrically-powered airship. The flight characteristics of the Hindenburg Zeppelin are used as a model for a modern cargo airship. The supply chain cost of trucking tomatoes is used to test the theorical proposition. The cost difference works out to about US10￠/kg (5￠/lb) advantage for trucking Mexican tomatoes to Canada. However, this cost disadvantage of the airship could be made up by their vibrationless ride, better air circulation and one-day service versus four days by truck. This alternative form of transportation could have a positive impact on worldwide north-south distribution of food. Airships can overcome trade barriers and distance to open new markets for perishable food exports. In addition, they would reduce the carbon emissions of transport. Canada imports 160,000 refrigerated truckloads of fruits and vegetables by from the southern US and Mexico. With an average driving distance of 3,000 km, these trucks emit 606,000 MT of CO<sub>2</sub> annually. Airships powered by hydrogen fuel cells would have zero-carbon emissions. Markets are not yet incorporating the environmental advantage of airships in any freight comparison, but inevitably this will be important.展开更多
In this paper,a design method of moving-mass stratospheric airship with constant total mass is presented,and the general dynamics equation based on Newton-Euler method is derived.Considering the timedelay of the slide...In this paper,a design method of moving-mass stratospheric airship with constant total mass is presented,and the general dynamics equation based on Newton-Euler method is derived.Considering the timedelay of the slider command response and the dynamic coupling to the airship’s state parameters,a position tracking controller with input and state constraints was designed to make the dynamic response system of the slider have critical damping characteristics.By taking the longitudinal attitude motion of moving-mass stratospheric airship as the research object,parametric modeling and attitude control simulation were carried out,and the attitude control ability of moving-mass control under different mass ratios was analyzed.The simulation results show that the attitude control ability is not affected by airspeed,and the mass ratio of slider is the main factor affecting the attitude control ability.The parameters of the slider controller have a direct influence on the dynamic performance of attitude control and also determine the dynamic coupling level of the airship.Compared with the attitude control based on the aerodynamic control surface,moving-mass control can make the airspeed and attack angle converged to the initial state at the steady state,and keep a good aerodynamic shape.展开更多
Airship shape is crucial to the design of stratosphere airships. In this paper, multidisciplinary design optimization (MDO) technology is introduced into the design of airship shape. We devise a composite objective fu...Airship shape is crucial to the design of stratosphere airships. In this paper, multidisciplinary design optimization (MDO) technology is introduced into the design of airship shape. We devise a composite objective function, based on this technology, which takes account of various factors which influence airship performance, including aerodynamics, structures, energy and weight to determine the optimal airship shape. A shape generation algorithm is proposed and appropriate mathematical models are constructed. Simulation results show that the optimized shape gives an improvement in the value of the composite objective function compared with a reference shape.展开更多
This paper presents an experimental study to determine the tensile properties of the envelope fabric Uretek3216L under biaxial cyclic loading.First the biaxial cyclic tests were carefully carried out on the envelope m...This paper presents an experimental study to determine the tensile properties of the envelope fabric Uretek3216L under biaxial cyclic loading.First the biaxial cyclic tests were carefully carried out on the envelope material to obtain the stress-strain data and the corresponding nonlinearity and orthotropy of the material were analyzed. Then for some determination options with different stress ratios the least squares method minimizing the strain terms was used to calculate the elastic constants from the experimental data.Finally the influences of the determination options with different stress ratios and the reciprocal relationship on the elastic constants were discussed.Results show that the orthotropy of the envelope material can be attributed to the unbalanced crimp of their constitutive yarns in warp and weft directions and the elastic constants vary noticeably with the determination options as well as the normalized stress ratios.In real design practice it is more reasonable to use constants determined for specific stress states in particular stress ratios depending on the project＆#39;s needs.Also calculating the structures with two limitative sets of elastic constants instead of using only one set is recommendable in light of the great variety of the constant＆#39;s values.展开更多
The attitude control problem and the guidance problem are solved in 3-D for a buoyancy-driven airship actuated by the combined effects of an internal air bladder which modulates the airshiprs net weight and of two mov...The attitude control problem and the guidance problem are solved in 3-D for a buoyancy-driven airship actuated by the combined effects of an internal air bladder which modulates the airshiprs net weight and of two moving masses which modulate its center of mass. A simple and clear modeling is introduced to derive the 8 degree of freedom （DOF） mathematical model. Nonlinear control loops are derived through maximal feedback linearization with internal stability for both dynamics in the longitudinal plane and in the lateral plane. Based on a singular perturbation approach, the superposition of these two control actions in the longitudinal plane and in the lateral plane is shown to achieve the control of the dynamics in 3-D space. The simulations of the airship tracking specified attitude, moving direction and speed in 3-D space are presented.展开更多
This paper proposes a hybrid architecture based on Multi-disciplinary Design Optimization(MDO) with the Variable Complexity Modeling(VCM) method, to solve the problem of general design optimization for a stratosphere ...This paper proposes a hybrid architecture based on Multi-disciplinary Design Optimization(MDO) with the Variable Complexity Modeling(VCM) method, to solve the problem of general design optimization for a stratosphere airship. Firstly, MDO based on the Concurrent SubSpace Optimization(CSSO) strategy is improved for handling the subsystem coupling problem in stratosphere airship design which contains aerodynamics, structure, and energy. Secondly, the VCM method based on the surrogate model is presented for reducing the computational complexity in high-fidelity modeling without loss of accuracy. Moreover, the global-to-local optimization strategy is added to the architecture to enhance the process. Finally, the result gives a prominent stratosphere airship general solution that validates the feasibility and efficiency of the optimization architecture. Besides, a sensitivity analysis is conducted to outline the critical impact upon stratosphere airship design.展开更多
Deformation behavior of non-rigid airships in wind tunnel tests is studied by considering three factors, including internal pressure, flow velocity and angle of attack. Fiber Bragg grating strain sensors are used to m...Deformation behavior of non-rigid airships in wind tunnel tests is studied by considering three factors, including internal pressure, flow velocity and angle of attack. Fiber Bragg grating strain sensors are used to measure the deformation of non-rigid airships. Wind tunnel tests in the case of different flow velocities and angles of attack are conducted. The measurement results reveal that the airship deformation is in proportion to internal pressure. For the tensile region,the airship deformation is in proportion to flow velocity. Effects of angle of attack on structural deformation are more complicated and there is no clear relationship existing between airship deformation and angle of attack.展开更多
Stratospheric airship is a special near-space air vehicle,and has more advantages than other air vehicles,such as long endurance,strong survival ability,excellent resolution,low cost,and so on,which make it an ideal s...Stratospheric airship is a special near-space air vehicle,and has more advantages than other air vehicles,such as long endurance,strong survival ability,excellent resolution,low cost,and so on,which make it an ideal stratospheric platform.It is of great significance to choose a reasonable and effective way to launch a stratospheric airship to the space for both academic research and engineering applications.In this paper,the non-forming launch way is studied and the method of differential pressure gradient is used to study the change rules of the airship＇s envelope shape during the ascent process.Numerical simulation results show that the head of the envelope will maintain the inflatable shape and the envelope under the zero-pressure level will be compressed into a wide range of wrinkles during the ascent process.The airship＇s envelope will expand with the ascent of the airship and the position of the zero-pressure level will move downward constantly.At the same time,the envelope will gradually form a certain degree of stiffness under the action of the inner and external differential pressure.The experimental results agree well with the analytical results,which shows that the non-forming launch way is effective and reliable,and the analytical method has exactness and feasibility.展开更多
The stabilization and trajectory tracking problems of autonomous airship＇s planar motion are studied. By defining novel configuration error and velocity error, the dynamics of error systems are derived. By applying L...The stabilization and trajectory tracking problems of autonomous airship＇s planar motion are studied. By defining novel configuration error and velocity error, the dynamics of error systems are derived. By applying Lyapunov stability method, the state feedback control laws are designed and the close-loop error systems are proved to be uniformly asymptotically stable by Matrosov theorem. In particular, the controller does not need knowledge on system parameters in the case of set-point stabilization, which makes the controller robust with respect to parameter uncertainty. Numerical simulations illustrate the effectiveness of the controller designed.展开更多
Total dynamics of an airship is modeled. The body of an airship is taken as a submerged rigid body with neutral buoyancy, i. e. , buoyancy with value equal to that of gravity, and the coupled dynamics between the body...Total dynamics of an airship is modeled. The body of an airship is taken as a submerged rigid body with neutral buoyancy, i. e. , buoyancy with value equal to that of gravity, and the coupled dynamics between the body with ballonets and ballast is considered. The total dynamics of the airship is firstly derived by Newton-Euler laws and Kirchhoff＇ s equations. Furthermore, by using Hamiltonian and Lagrangian semidirect product reduction theories, the dynamics is formulated as a Lie-Poisson system, or also an Euler-Poincare system. These two formulations can be exploited for the control design using energy-based methods for Hamiltonian or Lagrangian system.展开更多
This paper deals with an improved bonding approach of surface-bonded fiber Bragg grating (FBG) sensors for airship envelope structural health monitoring (SHM) under the strain transfer theory. A theoretical formula is...This paper deals with an improved bonding approach of surface-bonded fiber Bragg grating (FBG) sensors for airship envelope structural health monitoring (SHM) under the strain transfer theory. A theoretical formula is derived from the proposed model to predict the strain transfer relationship between the airship envelope and fiber core. Then theoretical predictions are validated by numerical analysis using the finite element method (FEM). Finally, on the basis of the theoretical approach and numerical validation, parameters that influence the strain transfer rate from the airship envelope to fiber core and the ratio of effective sensing length are analyzed, and some meaningful conclusions are provided.展开更多
An adaptive fuzzy sliding mode control （AFSMC） ap- proach is proposed for a robotic airship. First, the mathematical model of an airship is derived in the form of a nonlinear control system. Second, an AFSMC approac...An adaptive fuzzy sliding mode control （AFSMC） ap- proach is proposed for a robotic airship. First, the mathematical model of an airship is derived in the form of a nonlinear control system. Second, an AFSMC approach is proposed to design the attitude control system of airship, and the global stability of the closed-loop system is proved by using the Lyapunov stability theorem. Finally, simulation results verify the effectiveness and robustness of the proposed control approach in the presence of model uncertainties and external disturbances.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51775021,52302511)the Fundamental Research Funds for the Central Universities,China(Nos.YWF-23-JC-01,YWF-23-JC-04,YWF-23-JC-09)。
文摘Stratospheric airships are lighter-than-air vehicles capable of continuous flying for months.The energy balance of the airship is the key to long-duration flights.The stratospheric airship is entirely powered by the solar array.It is necessary to accurately predict the output power of the array for any flight state.Because of the uneven solar radiation received by the solar array,the traditional model based on components has a slow simulation speed.In this study,a data-driven surrogate modeling approach for prediction the output power of the solar array is proposed.The surrogate model is trained using the samples obtained from the high-accuracy simulation model.By using the input parameter preprocessor,the accuracy of the surrogate model in predicting the output power of the solar array is improved to 98.65%.In addition,the predictive speed of the surrogate model is ten million times faster than the traditional simulation model.Finally,the surrogate model is used to predict the energy balance of stratospheric airships flying throughout the year under actual global wind fields.
基金supported by the National Natural Science Foundation of China(Nos.51775021,52302511)the Fundamental Research Funds for the Central Universities,China(Nos.501JCGG2024129003,501JCGG2024129005,501JCGG2024129006),the Fundamental Research Funds for the Central Universities,China(No.YWF-24-JC-09)the National Key Research and Development Program of China(No.2018YFC1506401)。
文摘This paper studies the tracking control problem for stratospheric airships with userspecified performance.Dealing with the infinite gain phenomenon in the prescribed-time stability,a new stability criterion with bounded gain is proposed by using a new time-varying scaling function.Moreover,a same-side performance function and a novel barrier Lyapunov function are incorporated into the control algorithm,which can compress the feasible domain of tracking error to minimize the overshoot and solve the difficult in tracking error not converging to zero simultaneously.The proposed scheme guarantees the airship capable of operating autonomously with satisfactory transient performance and tracking accuracy,where the performance parameters can be designed artificially and link to the physical process directly.Finally,the effectiveness of the proposed control scheme is verified by theoretical analysis and numerical simulation.
文摘The stratospheric airship is affected by harsh conditions in the stratosphere environment.To ensure the safety of the airship,it is necessary to detect the material state of the airship envelope.Since digital image correlation possesses non-contact strain measurement ability,this paper explores the infuence of different shapes of the subset on measurement accuracy.Through the results,it is found that increasing the aspect ratio of subsets can improve the strain accuracy measured in the c-direction,and reducing the aspect ratio can improve the strain accuracy measured in the y-direction.This trend becomes more obvious as the strain increases.Based on this discovery,a subset adaptive algorithm is proposed.The feasibility of the algorithm is verified by experiments,and the precision of strain measurement can be effectively improved by adjusting the threshold value.Therefore,the algorithm can be utilized to increase the measurement accuracy in the larger strain direction without changing the size of the subset.
文摘The robotic airship can provide a promising aerostatic platform for many potential applications.These applications require a precise autonomous trajectory tracking control for airship.Airship has a nonlinear and uncertain dynamics.It is prone to wind disturbances that offer a challenge for a trajectory tracking control design.This paper addresses the airship trajectory tracking problem having time varying reference path.A lumped parameter estimation approach under model uncertainties and wind disturbances is opted against distributed parameters.It uses extended Kalman filter(EKF)for uncertainty and disturbance estimation.The estimated parameters are used by sliding mode controller(SMC)for ultimate control of airship trajectory tracking.This comprehensive algorithm,EKF based SMC(ESMC),is used as a robust solution to track airship trajectory.The proposed estimator provides the estimates of wind disturbances as well as model uncertainty due to the mass matrix variations and aerodynamic model inaccuracies.The stability and convergence of the proposed method are investigated using the Lyapunov stability analysis.The simulation results show that the proposed method efficiently tracks the desired trajectory.The method solves the stability,convergence,and chattering problem of SMC under model uncertainties and wind disturbances.
基金supported by the National Natural Science Foundation of China(No.51775021)the Fundamental Research Funds for the Central Universities,China(Nos.YWF-23-JC-02,YWF-23-JC-09)。
文摘Stratospheric airships are long-endurance aerostats and have broad applications.All of the energy required for their operation is obtained from solar radiation,which makes accurate calculation of the energy output from the solar array crucial to the design and flight planning of the airships.However,the status of each photovoltaic module in the solar array may differ due to the airship curvature,resulting in mismatch losses and lowered output power,which has not been widely studied.In this paper,an irradiation model and a thermal model are established based on the actual arrangement of the modules.The output power model is established considering the non-uniform radiation in the array.The mismatch losses of the array are analyzed under different flight conditions.The output power of the solar array is decreased by up to 31.6%compared to the ideal state.Moreover,the proportion of mismatch losses increases with latitude,but the maximum mismatch loss power occurs at mid-latitudes.Then,an array reconfiguration method is proposed based on the irradiance dispersion index and position dispersion index.The reconfigured array increases output power by 11.5%and can maintain energy balance in continuous flight.The results can be used to correct the overestimation of the output power during the airship design or to guide the configuration of the solar array.
基金supported by the Aeronautical Science Foundation of China(2017ZA88001)National Natural Science Foundation of China(11502288)and China Postdoctoral Science Foundation(47661).
文摘The robotic airship is one of the most unique and promising green aircraft,however,as a“lighter-than-air aircraft”and“thermal aircraft”,its long-endurance flight has great difficulties in decreasing drag and controlling buoyancy and pressure under thermal effects.In this work,we reported a robotic airship inspired by the Physalia physalis,imitating its morphology,physiological structure,and biological behaviors.The hull is designed by imitating the morphology of the Physalia physalis,and the gasbags including a helium balloon,two ballonets,and a thermoregulation gasbag are designed by imitating the physiological structure and biological behaviors of the pneumatophore,bladder,and gland of the Physalia physalis,respectively.Experimental results show that the bionic airship has an increase of about 40%in lift-to-drag and decreases the pressure in helium balloon by 47.5%under thermal effects,and has better aerodynamic performances and thermoregulation performances than conventional airships.
基金supported by the National Natural Science Foundation of China(Nos.62073019,62227810).
文摘The current study focuses on the motion-pressure coupled control for a multicapsule stratospheric airship and transforms the path-tracking and heading-hold control of airships into guidance tracking with a time-varying weighted sum of longitudinal and lateral velocities by the definition of compound speed.Herein,an improved nonlinear predictive control method is provided to reduce the control energy consumption by the rolling optimization of controller parameters based on finite time intervals,ensuring infinite-time path-tracking tasks.Simultaneously,combined with the proposed cyclic regulation process of safe pressure between internal and external capsules,this study can fully reflect the force-thermal coupled rule of airships under the actions of atmospheric environment and maneuvering force,while evaluating the long-endurance capability of airships under the conditions of safe superheating and overpressure.The effectiveness of the motionpressure coupled controller was verified through numerical simulations,which can overcome the influence of environmental wind and achieve a tracking effect for the desired cruise path and compound speed.The airspeed provided during the cyclic circadian time caused the maximum superheating of the helium controlled within 30C.The helium in the internal and external capsules achieved circadian regulation.The equivalent micropore diameter of the capsule of 5 mm can achieve 55 days of long-endurance flight.The controller satisfies the requirements of cruise-flight application modes for multicapsule stratospheric airships with important engineering value.
基金the National Natural Science Foundation of China (Nos.52302511,52202454,52202513).
文摘The voluminous stratospheric non-rigid airship is very sensitive to the external thermal environment.The temperature change of internal gas caused by the variation in the external ther-mal environment and wind speed will lead to a change in the shape and buoyancy of the airship,thereby affecting its flight control.The traditional static analysis method is difficult to accurately reflect this fuid-thermal-structural coupling process.In this paper,the iterative analysis method was established for the fluid-thermal-structural coupling effect of stratospheric non-rigid airship based on the models of fluid,thermal,and structural deformation.Considering the load such as the internal thermal effect and external flow field of the airship,the simulation of the thermo-induced structural deformation effect was conducted using Fluent and Abaqus software.The influ-ence of local time and external wind speed on the structural deformation,volume,and equilibrium altitude of the airship was analyzed.The results demonstrate that,at low wind speed,the influence of aerodynamic pressure on the deformation of the airship is negligible.However,a great amount of heat is carried away by the wind,then the structural deformation caused by internal and external pressure difference is alleviated and the equilibrium altitude of the airship change obviously.This can serve as a guideline for the design and flight test of the long-endurance stratospheric non-rigid airship.
文摘Intermodal competition changes with changes in technology, economics, and environmental concerns. Trucks and airships are generally considered not to be competitors, but this depends on the distance of haul. The tonne-kilometer cost of trucking rises much more quickly with distance than it does the cost of a cargo airship. At some distance, the two modes are direct substitutes. The costs of the Mexico-Canada refrigerated truck supply chain are compared with the costs of a 100t-lift, electrically-powered airship. The flight characteristics of the Hindenburg Zeppelin are used as a model for a modern cargo airship. The supply chain cost of trucking tomatoes is used to test the theorical proposition. The cost difference works out to about US10￠/kg (5￠/lb) advantage for trucking Mexican tomatoes to Canada. However, this cost disadvantage of the airship could be made up by their vibrationless ride, better air circulation and one-day service versus four days by truck. This alternative form of transportation could have a positive impact on worldwide north-south distribution of food. Airships can overcome trade barriers and distance to open new markets for perishable food exports. In addition, they would reduce the carbon emissions of transport. Canada imports 160,000 refrigerated truckloads of fruits and vegetables by from the southern US and Mexico. With an average driving distance of 3,000 km, these trucks emit 606,000 MT of CO<sub>2</sub> annually. Airships powered by hydrogen fuel cells would have zero-carbon emissions. Markets are not yet incorporating the environmental advantage of airships in any freight comparison, but inevitably this will be important.
基金the National Natural Science Foundation of China(No.51205253)。
文摘In this paper,a design method of moving-mass stratospheric airship with constant total mass is presented,and the general dynamics equation based on Newton-Euler method is derived.Considering the timedelay of the slider command response and the dynamic coupling to the airship’s state parameters,a position tracking controller with input and state constraints was designed to make the dynamic response system of the slider have critical damping characteristics.By taking the longitudinal attitude motion of moving-mass stratospheric airship as the research object,parametric modeling and attitude control simulation were carried out,and the attitude control ability of moving-mass control under different mass ratios was analyzed.The simulation results show that the attitude control ability is not affected by airspeed,and the mass ratio of slider is the main factor affecting the attitude control ability.The parameters of the slider controller have a direct influence on the dynamic performance of attitude control and also determine the dynamic coupling level of the airship.Compared with the attitude control based on the aerodynamic control surface,moving-mass control can make the airspeed and attack angle converged to the initial state at the steady state,and keep a good aerodynamic shape.
基金Project (No. 2007AA705003) supported by the National Hi-Tech Research and Development Program (863) of China
文摘Airship shape is crucial to the design of stratosphere airships. In this paper, multidisciplinary design optimization (MDO) technology is introduced into the design of airship shape. We devise a composite objective function, based on this technology, which takes account of various factors which influence airship performance, including aerodynamics, structures, energy and weight to determine the optimal airship shape. A shape generation algorithm is proposed and appropriate mathematical models are constructed. Simulation results show that the optimized shape gives an improvement in the value of the composite objective function compared with a reference shape.
基金The National Natural Science Foundation of China(No.51278299,50878128)
文摘This paper presents an experimental study to determine the tensile properties of the envelope fabric Uretek3216L under biaxial cyclic loading.First the biaxial cyclic tests were carefully carried out on the envelope material to obtain the stress-strain data and the corresponding nonlinearity and orthotropy of the material were analyzed. Then for some determination options with different stress ratios the least squares method minimizing the strain terms was used to calculate the elastic constants from the experimental data.Finally the influences of the determination options with different stress ratios and the reciprocal relationship on the elastic constants were discussed.Results show that the orthotropy of the envelope material can be attributed to the unbalanced crimp of their constitutive yarns in warp and weft directions and the elastic constants vary noticeably with the determination options as well as the normalized stress ratios.In real design practice it is more reasonable to use constants determined for specific stress states in particular stress ratios depending on the project＆#39;s needs.Also calculating the structures with two limitative sets of elastic constants instead of using only one set is recommendable in light of the great variety of the constant＆#39;s values.
基金Supported by the Scholarship Foundation of China Scholarship Council~~
文摘The attitude control problem and the guidance problem are solved in 3-D for a buoyancy-driven airship actuated by the combined effects of an internal air bladder which modulates the airshiprs net weight and of two moving masses which modulate its center of mass. A simple and clear modeling is introduced to derive the 8 degree of freedom （DOF） mathematical model. Nonlinear control loops are derived through maximal feedback linearization with internal stability for both dynamics in the longitudinal plane and in the lateral plane. Based on a singular perturbation approach, the superposition of these two control actions in the longitudinal plane and in the lateral plane is shown to achieve the control of the dynamics in 3-D space. The simulations of the airship tracking specified attitude, moving direction and speed in 3-D space are presented.
基金supported in part by the National Key R&D Program of China(No.2016YFB1200100)
文摘This paper proposes a hybrid architecture based on Multi-disciplinary Design Optimization(MDO) with the Variable Complexity Modeling(VCM) method, to solve the problem of general design optimization for a stratosphere airship. Firstly, MDO based on the Concurrent SubSpace Optimization(CSSO) strategy is improved for handling the subsystem coupling problem in stratosphere airship design which contains aerodynamics, structure, and energy. Secondly, the VCM method based on the surrogate model is presented for reducing the computational complexity in high-fidelity modeling without loss of accuracy. Moreover, the global-to-local optimization strategy is added to the architecture to enhance the process. Finally, the result gives a prominent stratosphere airship general solution that validates the feasibility and efficiency of the optimization architecture. Besides, a sensitivity analysis is conducted to outline the critical impact upon stratosphere airship design.
基金supported by the National Natural Science Foundation of China(Nos.11472276,11332011 and 11502268)
文摘Deformation behavior of non-rigid airships in wind tunnel tests is studied by considering three factors, including internal pressure, flow velocity and angle of attack. Fiber Bragg grating strain sensors are used to measure the deformation of non-rigid airships. Wind tunnel tests in the case of different flow velocities and angles of attack are conducted. The measurement results reveal that the airship deformation is in proportion to internal pressure. For the tensile region,the airship deformation is in proportion to flow velocity. Effects of angle of attack on structural deformation are more complicated and there is no clear relationship existing between airship deformation and angle of attack.
基金supported by the Achievements Cultivation Fund of Beihang University(No. YWF-15-CGPY-HKXY-001)
文摘Stratospheric airship is a special near-space air vehicle,and has more advantages than other air vehicles,such as long endurance,strong survival ability,excellent resolution,low cost,and so on,which make it an ideal stratospheric platform.It is of great significance to choose a reasonable and effective way to launch a stratospheric airship to the space for both academic research and engineering applications.In this paper,the non-forming launch way is studied and the method of differential pressure gradient is used to study the change rules of the airship＇s envelope shape during the ascent process.Numerical simulation results show that the head of the envelope will maintain the inflatable shape and the envelope under the zero-pressure level will be compressed into a wide range of wrinkles during the ascent process.The airship＇s envelope will expand with the ascent of the airship and the position of the zero-pressure level will move downward constantly.At the same time,the envelope will gradually form a certain degree of stiffness under the action of the inner and external differential pressure.The experimental results agree well with the analytical results,which shows that the non-forming launch way is effective and reliable,and the analytical method has exactness and feasibility.
文摘The stabilization and trajectory tracking problems of autonomous airship＇s planar motion are studied. By defining novel configuration error and velocity error, the dynamics of error systems are derived. By applying Lyapunov stability method, the state feedback control laws are designed and the close-loop error systems are proved to be uniformly asymptotically stable by Matrosov theorem. In particular, the controller does not need knowledge on system parameters in the case of set-point stabilization, which makes the controller robust with respect to parameter uncertainty. Numerical simulations illustrate the effectiveness of the controller designed.
文摘Total dynamics of an airship is modeled. The body of an airship is taken as a submerged rigid body with neutral buoyancy, i. e. , buoyancy with value equal to that of gravity, and the coupled dynamics between the body with ballonets and ballast is considered. The total dynamics of the airship is firstly derived by Newton-Euler laws and Kirchhoff＇ s equations. Furthermore, by using Hamiltonian and Lagrangian semidirect product reduction theories, the dynamics is formulated as a Lie-Poisson system, or also an Euler-Poincare system. These two formulations can be exploited for the control design using energy-based methods for Hamiltonian or Lagrangian system.
基金Project (No. 2011AA7052011) supported by the National High-Tech R&D (863) Program of China
文摘This paper deals with an improved bonding approach of surface-bonded fiber Bragg grating (FBG) sensors for airship envelope structural health monitoring (SHM) under the strain transfer theory. A theoretical formula is derived from the proposed model to predict the strain transfer relationship between the airship envelope and fiber core. Then theoretical predictions are validated by numerical analysis using the finite element method (FEM). Finally, on the basis of the theoretical approach and numerical validation, parameters that influence the strain transfer rate from the airship envelope to fiber core and the ratio of effective sensing length are analyzed, and some meaningful conclusions are provided.
基金supported by the Hunan Provincial Innovation Foundation for Postgraduate (CX2011B005)the National University of Defense Technlolgy Innovation Foundation for Postgraduate (B110105)
文摘An adaptive fuzzy sliding mode control （AFSMC） ap- proach is proposed for a robotic airship. First, the mathematical model of an airship is derived in the form of a nonlinear control system. Second, an AFSMC approach is proposed to design the attitude control system of airship, and the global stability of the closed-loop system is proved by using the Lyapunov stability theorem. Finally, simulation results verify the effectiveness and robustness of the proposed control approach in the presence of model uncertainties and external disturbances.
