This work proposes the application of an iterative learning model predictive control(ILMPC)approach based on an adaptive fault observer(FOBILMPC)for fault-tolerant control and trajectory tracking in air-breathing hype...This work proposes the application of an iterative learning model predictive control(ILMPC)approach based on an adaptive fault observer(FOBILMPC)for fault-tolerant control and trajectory tracking in air-breathing hypersonic vehicles.In order to increase the control amount,this online control legislation makes use of model predictive control(MPC)that is based on the concept of iterative learning control(ILC).By using offline data to decrease the linearized model’s faults,the strategy may effectively increase the robustness of the control system and guarantee that disturbances can be suppressed.An adaptive fault observer is created based on the suggested ILMPC approach in order to enhance overall fault tolerance by estimating and compensating for actuator disturbance and fault degree.During the derivation process,a linearized model of longitudinal dynamics is established.The suggested ILMPC approach is likely to be used in the design of hypersonic vehicle control systems since numerical simulations have demonstrated that it can decrease tracking error and speed up convergence when compared to the offline controller.展开更多
Hypersonic boundary-layer receptivity to freestream entropy and vorticity waves is investigated using direct numerical simula-tions for a Mach 6 flow over a 5.08 mm nose radius cone.Two frequencies of 33 kHz and 150 k...Hypersonic boundary-layer receptivity to freestream entropy and vorticity waves is investigated using direct numerical simula-tions for a Mach 6 flow over a 5.08 mm nose radius cone.Two frequencies of 33 kHz and 150 kHz are considered to be rep-resentative of the first and second instability modes,respectively.For the first mode,wall pressure fluctuations for both entropy and vorticity wave cases exhibit a strong modulation yet without a growing trend,indicating that the first mode is not generated despite its instability predicted by linear stability theory.The potential reason for this is the absence of postshock slow acoustic waves capable of synchronizing with the first mode.By contrast,for the second mode,a typical three-stage boundary-layer response is observed,consistent with that to slow acoustic waves studied previously.Furthermore,the postshock disturbances outside the boundary layer can be decomposed into the entropy(density/temperature fluctuations)and vorticity components(ve-locity fluctuations),and the latter is shown to play a leading role in generating the second mode,even for the case with entropy waves where the density/temperature fluctuations dominate the postshock regions.展开更多
In hypersonic boundary layers,the optimal disturbance is notably caused by normalmode instabilities,such as Mack second mode.However,recent experimental and numerical efforts have demonstrated the dominance of nonmoda...In hypersonic boundary layers,the optimal disturbance is notably caused by normalmode instabilities,such as Mack second mode.However,recent experimental and numerical efforts have demonstrated the dominance of nonmodal growth in hypersonic flows with the presence of moderate nose bluntness.In this study,resolvent analysis and parabolized stability equation analysis are performed to investigate the instabilities over a blunt-tip wedge.Main parameters include Mach number 5.9,unit Reynolds number 91.5×10~6/m,half wedge angle 5°,and nose radii ranging from 2.54 mm to 15.24 mm.Two novel growth patterns of travelling waves are identified to compete,whose nature is the intersection of the energy gain of optimal and sub-optimal disturbances.Pattern A with large spanwise wavelengths has the signature of slow energy amplification over a long distance which concentrates in the entropy layer.By contrast,pattern B with relatively small spanwise wavelengths presents rapid transient growth inside the boundary layer.A systematic study is performed on the growth/attenuation mechanism of disturbance patterns and the effects of wall temperature and nose radius.Wall cooling is found to be an alternative control strategy aimed at nonmodal instabilities.The receptivity to slow acoustic waves is considered when the effect of bluntness is studied.An estimated amplitude response favorably reproduces the reversal-like phenomenon.The lift-up/Orr mechanism analysis provides an explanation of energy growth for nonmodal responses.展开更多
In practical combat scenarios,Hypersonic Glide Vehicles(HGV)face the challenge of evading Successive Pursuers from the Same Direction while satisfying the Homing Constraint(SPSDHC).To address this problem,this paper p...In practical combat scenarios,Hypersonic Glide Vehicles(HGV)face the challenge of evading Successive Pursuers from the Same Direction while satisfying the Homing Constraint(SPSDHC).To address this problem,this paper proposes a parameterized evasion guidance algorithm based on reinforcement learning.The three-player optimal evasion strategy is firstly analyzed and approximated by parametrization.The switching acceleration command of HGV optimal evasion strategy considering the upper limit of missile acceleration command is analyzed based on the optimal control theory.The terminal miss of HGV in the case of evading two missiles is analyzed,which means that the three-player optimal evasion strategy is a linear combination of two one-toone strategies.Then,a velocity control algorithm is proposed to increase the terminal miss by actively controlling the flight speed of the HGV based on the parametrized evasion strategy.The reinforcement learning method is used to implement the strategy in real time and a reward function is designed by deducing homing strategy for the HGV to approach the target,which ensures that the HGV satisfies the homing constraint.Experimental results demonstrate the feasibility and robustness of the proposed parameterized evasion strategy,which enables the HGV to generate maximum terminal miss and satisfy homing constraint when facing single or double missiles.展开更多
For the longitudinal midcourse guidance problem of a cruise-glide integrated hypersonic vehicle(CGHV),an analytical method based on optimal control theory is proposed.This method constructs a guidance dynamics model f...For the longitudinal midcourse guidance problem of a cruise-glide integrated hypersonic vehicle(CGHV),an analytical method based on optimal control theory is proposed.This method constructs a guidance dynamics model for such vehicles,using aerodynamic load as the control variable,and introduces a framework for solving the guidance laws.This framework unifies the design process of guidance laws for both the glide and cruise phases.By decomposing the longitudinal guidance task into position control and velocity control,and minimizing energy consumption as the objective function,the method provides an analytical solution for velocity control load through the calculation of costate variables.This approach requires only the current state and terminal state parameters to determine the guidance law solution.Furthermore,by transforming path constraints into aerodynamic load constraints and solving backwards to obtain the angle of attack,bank angle,and throttle setting,this method ensures a smooth transition from the glide phase to the cruise phase,guaranteeing the successful completion of the guidance task.Finally,the effectiveness and practicality of the proposed method are validated through case simulations and analysis.展开更多
The precise characterization of hypersonic glide vehicle(HGV) maneuver laws in complex flight scenarios still faces challenges. Non-stationary changes in flight state due to abrupt changes in maneuver modes place high...The precise characterization of hypersonic glide vehicle(HGV) maneuver laws in complex flight scenarios still faces challenges. Non-stationary changes in flight state due to abrupt changes in maneuver modes place high demands on the accuracy of modeling methods. To address this issue, a novel maneuver laws modeling and analysis method based on higher order multi-resolution dynamic mode decomposition(HMDMD) is proposed in this work. A joint time-space-frequency decomposition of the vehicle's state sequence in the complex flight scenario is achieved with the higher order Koopman assumption and standard multi-resolution dynamic mode decomposition, and an approximate dynamic model is established. The maneuver laws can be reconstructed and analyzed with extracted multi-scale spatiotemporal modes with clear physical meaning. Based on the dynamic model of HGV, two flight scenarios are established with constant angle of attack and complex maneuver laws, respectively. Simulation results demonstrate that the maneuver laws obtained using the HMDMD method are highly consistent with those derived from the real dynamic model, the modeling accuracy is better than other common modeling methods, and the method has strong interpretability.展开更多
Hypersonic Glide Vehicles(HGVs)are advanced aircraft that can achieve extremely high speeds(generally over 5 Mach)and maneuverability within the Earth's atmosphere.HGV trajectory prediction is crucial for effectiv...Hypersonic Glide Vehicles(HGVs)are advanced aircraft that can achieve extremely high speeds(generally over 5 Mach)and maneuverability within the Earth's atmosphere.HGV trajectory prediction is crucial for effective defense planning and interception strategies.In recent years,HGV trajectory prediction methods based on deep learning have the great potential to significantly enhance prediction accuracy and efficiency.However,it's still challenging to strike a balance between improving prediction performance and reducing computation costs of the deep learning trajectory prediction models.To solve this problem,we propose a new deep learning framework(FECA-LSMN)for efficient HGV trajectory prediction.The model first uses a Frequency Enhanced Channel Attention(FECA)module to facilitate the fusion of different HGV trajectory features,and then subsequently employs a Light Sampling-oriented Multi-Layer Perceptron Network(LSMN)based on simple MLP-based structures to extract long/shortterm HGV trajectory features for accurate trajectory prediction.Also,we employ a new data normalization method called reversible instance normalization(RevIN)to enhance the prediction accuracy and training stability of the network.Compared to other popular trajectory prediction models based on LSTM,GRU and Transformer,our FECA-LSMN model achieves leading or comparable performance in terms of RMSE,MAE and MAPE metrics while demonstrating notably faster computation time.The ablation experiments show that the incorporation of the FECA module significantly improves the prediction performance of the network.The RevIN data normalization technique outperforms traditional min-max normalization as well.展开更多
This paper concentrates on addressing the hypersonic glide vehicle(HGV)tracking problem considering the high maneuverability and non-stationary heavy-tailed measurement noise without prior statistics in complicated fl...This paper concentrates on addressing the hypersonic glide vehicle(HGV)tracking problem considering the high maneuverability and non-stationary heavy-tailed measurement noise without prior statistics in complicated flight environments.Since the interacting multiple model(IMM)filtering is famous with its ability to cover the movement property of motion models,the problem is formulated as modeling the non-stationary heavy-tailed measurement noise without any prior statistics in the IMM framework.Firstly,without any prior statistics,the Gaussian-inverse Wishart distribution is embedded in the improved Pearson type-VII(PTV)distribution,which can adaptively adjust the parameters to model the non-stationary heavytailed measurement noise.Besides,degree of freedom(DOF)parameters are surrogated by the maximization of evidence lower bound(ELBO)in the variational Bayesian optimization framework instead of fixed value to handle uncertain non-Gaussian degrees.Then,this paper analytically derives fusion forms based on the maximum Versoria fusion criterion instead of the moment matching approach,which can provide a precise approximation for the PTV mixture distribution in the mixing and output steps combined with the weight Kullback-Leibler average theory.Simulation results demonstrate the superiority and robustness of the proposed algorithm in typical HGVs tracking when the measurement noise without priori statistics is non-stationary.展开更多
During the re-entry of a hypersonic aircraft into the earth’s atmosphere,the surrounding air experiences dissociation,ionization,and other complex chemical phenomena due to extreme temperature by shock wave.To ensure...During the re-entry of a hypersonic aircraft into the earth’s atmosphere,the surrounding air experiences dissociation,ionization,and other complex chemical phenomena due to extreme temperature by shock wave.To ensure thermal safety,the thermochemical non-equilibrium effects resulting from real-gas behavior should be taken into account.In this paper,the characteristics of a double-cone hypersonic laminar flow,including distributions of wall pressure,heat flux,and species dissociation are numerically analyzed with incoming enthalpy of 9.65-21.77 MJ/kg.The thermochemical non-equilibrium flow at different enthalpy and wall temperatures is performed with two-temperature model and Park’s seven chemical reaction model.It is found that the doublecone flow features complex shock-shock interactions to form triple points.The flow topology is further brought out from the analysis of streamlines.At the lowest incoming enthalpy with isothermal wall conditions,two foci points appear.While others highlight only one focal point.As the increment of incoming enthalpy,the heat flux and dissociation of nitrogen and oxygen also increase.An increasing wall temperature leads to a larger separation bubble and a lower value of heat flux and pressure peak,while massive dissociation occurs without obvious ionization under considered cases.展开更多
Active disturbance rejection controller（ADRC）uses tracking-differentiator（TD）to solve the contradiction between the overshoot and the rapid nature.Fractional order proportion integral derivative（PID）controller i...Active disturbance rejection controller（ADRC）uses tracking-differentiator（TD）to solve the contradiction between the overshoot and the rapid nature.Fractional order proportion integral derivative（PID）controller improves the control quality and expands the stable region of the system parameters.ADRC fractional order（ADRFO）PID controller is designed by combining ADRC with the fractional order PID and applied to reentry attitude control of hypersonic vehicle.Simulation results show that ADRFO PID controller has better control effect and greater stable region for the strong nonlinear model of hypersonic flight vehicle under the influence of external disturbance,and has stronger robustness against the perturbation in system parameters.展开更多
The vibration characteristics of transverse oscillation of an axially moving beam with high velocity is in- vestigated. The vibration equation and boundary conditions of the free-free axially moving beam are derived u...The vibration characteristics of transverse oscillation of an axially moving beam with high velocity is in- vestigated. The vibration equation and boundary conditions of the free-free axially moving beam are derived using Hamilton＇s principle. Furthermore, the linearized equations are set up based on Galerkinl s method for the ap- proximation solution. Finally, three influencing factors on the vibration frequency of the beam are considered： （1） The axially moving speed. The first order natural frequency decreases as the axial velocity increases, so there is a critical velocity of the axially moving beam. （2） The mass loss. The changing of the mass density of some part of the beam increases the beam natural frequencies. （3） The thermal effect.＇ The temperature increase will decrease the beam elastic modulus and induce the vibration frequencies descending.展开更多
A parallel virtual machine （PVM） protocol based parallel computation of 3-D hypersonic flows with chemical non-equilibrium on hybrid meshes is presented. The numerical simulation for hypersonic flows with chemical n...A parallel virtual machine （PVM） protocol based parallel computation of 3-D hypersonic flows with chemical non-equilibrium on hybrid meshes is presented. The numerical simulation for hypersonic flows with chemical non-equilibrium reactions encounters the stiffness problem, thus taking huge CPU time. Based on the domain decomposition method, a high efficient automatic domain decomposer for three-dimensional hybrid meshes is developed, and then implemented to the numerical simulation of hypersonic flows. Control equations are multicomponent N-S equations, and spatially discretized scheme is used by a cell-centered finite volume algorithm with a five-stage Runge-Kutta time step. The chemical kinetic model is a seven species model with weak ionization. A point-implicit method is used to solve the chemical source term. Numerical results on PC-Cluster are verified on a bi-ellipse model compared with references.展开更多
Air-breathing hypersonic vehicle has great military and potential economic value due to its characteristics:high velocity,long range,quick response.Therefore,the development of hypersonic vehicle and its guidance and ...Air-breathing hypersonic vehicle has great military and potential economic value due to its characteristics:high velocity,long range,quick response.Therefore,the development of hypersonic vehicle and its guidance and control technology are reviewed in this paper.Firstly,the development and classification of hypersonic vehicles around the world are summarized,and the geometric configuration and mission profile of typical air-breathing hypersonic vehicle are given.Secondly,the control difficulties of air-breathing hypersonic vehicle are introduced,including integrated design of engine and fuselage,static instability,strong nonlinearity,uncertain aerodynamic parameters,etc.According to its control requirements,the control methods considering external disturbance,fault-tolerant control methods,anti-saturation methods,and prescribed performance control methods considering transient performance constraints are summarized respectively.The classification and comparison of various control methods are given,and the frontiers of theoretical development are analyzed.Finally,considering the effects of composite disturbances,the design of terminal guidance law under multiple constraints is overviewed,including guidance law with angle constraint,velocity constraint,acceleration constraint and time constraint.Similarly,the classification of guidance law design methods under different constraints,their advantages as well as the future development trend and requirements are introduced.展开更多
Designing re-entry space vehicles and high-speed aircraft requires special attention to the nonlinear thermoelastic and aerodynamic instability of their structural components. The thermal effects are important since t...Designing re-entry space vehicles and high-speed aircraft requires special attention to the nonlinear thermoelastic and aerodynamic instability of their structural components. The thermal effects are important since temperature environment brings dramatic influences on the static and dynamic behaviors of flight structures in supersonic/hypersonic regimes and is likely to cause instability, catastrophic failure and oscillations resulting in structural failure due to fatigue. In order to understand the dynamic behaviors of these ＂hot＂ structures, a double-wedge lifting surface with combining freeplay and cubic structural nonlinearities in both plunging and pitching degrees-of-freedom operating in supersonic/hypersonic flight speed regimes has been analyzed. A third order piston theory aerodynamic is used to estimate the applied nonlinear unsteady aerodynamic loads. Also considered is the loss of torsional stiffness that may be incurred by lifting surfaces subject to axial stresses induced by aerodynamic heating. The aerodynamic heating effects are estimated based on the adiabatic wall temperature due to high speed airstreams. As a recently emerging technology, the active aerothermoelastic control is aimed at providing solutions to a large number of problems involving the aeronautical/aerospace flight vehicle structures. To prevent such damaging phenomena from occurring, an application of linear and nonlinear active control methods on both flutter boundary and post-flutter behavior has been fulfilled. In this paper, modeling issues as well as numerical simulation have been presented and pertinent conclusions outlined. It is evidenced that a serious loss of torsional stiffness may induce the dynamic instability; however active control can be used to expand the flutter boundary and convert unstable limit cycle oscillations （LCO） into the stable LCO and/or to shift the transition between these two states toward higher flight Mach numbers.展开更多
Hypersonic vehicles with turbojet, ramjet, and scramjet engines are expected to be widely applied to future transportation systems. Due to high-speed flight in the atmosphere, body outer surfaces suffer strong aerodyn...Hypersonic vehicles with turbojet, ramjet, and scramjet engines are expected to be widely applied to future transportation systems. Due to high-speed flight in the atmosphere, body outer surfaces suffer strong aerodynamic heating, and on the other hand, combustion chamber inter walls are under extremely high temperature and heat flux. Therefore, more efficient and stable active cooling technologies are required in hypersonic vehicles, such as regenerative cooling, film cooling, and transpiration cooling, as well as their combinations. This paper presents a comprehensive literature review on three active cooling methods, i.e., regenerative cooling, film cooling, and transpiration cooling, and deeply analyzes the mechanism of each cooling method, including the fluids flow, heat transfer, and thermal cracking characteristics of different hydrocarbon fuels in regenerative cooling,the heat transfer and flow mechanism of film cooling under supersonic mainstream conditions, and the heat transfer and flow mechanism of transpiration cooling.展开更多
Abstract This paper presents the novel use of the particle swarm optimization （PSO） to generate the end-to-end trajectory for hypersonic reentry vehicles in a quite simple formulation. The velocity- dependent bank a...Abstract This paper presents the novel use of the particle swarm optimization （PSO） to generate the end-to-end trajectory for hypersonic reentry vehicles in a quite simple formulation. The velocity- dependent bank angle profile is developed to reduce the search space of unknown parameters based on the constrained PSO algorithm. The path constraints are enforced by setting the fitness function to be infinite on condition that the particles violate the maximum allowable values. The PSO algo- rithm also provides a much easier means to satisfy the terminal conditions by adding penalty terms to the fitness function. Furthermore, the approximate reentry landing footprint is fast constructed by incorporating an interpolation model into the standardized bank angle profiles. Numerical sim ulations demonstrate that the PSO method is a feasible and flexible tool to generate the end-to-end trajectory and landing footprint for hypersonic reentry vehicles.展开更多
基金supported by the National Natural Science Foundation of China(12072090).
文摘This work proposes the application of an iterative learning model predictive control(ILMPC)approach based on an adaptive fault observer(FOBILMPC)for fault-tolerant control and trajectory tracking in air-breathing hypersonic vehicles.In order to increase the control amount,this online control legislation makes use of model predictive control(MPC)that is based on the concept of iterative learning control(ILC).By using offline data to decrease the linearized model’s faults,the strategy may effectively increase the robustness of the control system and guarantee that disturbances can be suppressed.An adaptive fault observer is created based on the suggested ILMPC approach in order to enhance overall fault tolerance by estimating and compensating for actuator disturbance and fault degree.During the derivation process,a linearized model of longitudinal dynamics is established.The suggested ILMPC approach is likely to be used in the design of hypersonic vehicle control systems since numerical simulations have demonstrated that it can decrease tracking error and speed up convergence when compared to the offline controller.
基金supported by the National Natural Science Foundation of China(GrantNo.12072231).
文摘Hypersonic boundary-layer receptivity to freestream entropy and vorticity waves is investigated using direct numerical simula-tions for a Mach 6 flow over a 5.08 mm nose radius cone.Two frequencies of 33 kHz and 150 kHz are considered to be rep-resentative of the first and second instability modes,respectively.For the first mode,wall pressure fluctuations for both entropy and vorticity wave cases exhibit a strong modulation yet without a growing trend,indicating that the first mode is not generated despite its instability predicted by linear stability theory.The potential reason for this is the absence of postshock slow acoustic waves capable of synchronizing with the first mode.By contrast,for the second mode,a typical three-stage boundary-layer response is observed,consistent with that to slow acoustic waves studied previously.Furthermore,the postshock disturbances outside the boundary layer can be decomposed into the entropy(density/temperature fluctuations)and vorticity components(ve-locity fluctuations),and the latter is shown to play a leading role in generating the second mode,even for the case with entropy waves where the density/temperature fluctuations dominate the postshock regions.
基金supported by the Hong Kong Research Grants Council(Nos.15216621,15204322,25203721)the National Natural Science Foundation of China(No.12102377)。
文摘In hypersonic boundary layers,the optimal disturbance is notably caused by normalmode instabilities,such as Mack second mode.However,recent experimental and numerical efforts have demonstrated the dominance of nonmodal growth in hypersonic flows with the presence of moderate nose bluntness.In this study,resolvent analysis and parabolized stability equation analysis are performed to investigate the instabilities over a blunt-tip wedge.Main parameters include Mach number 5.9,unit Reynolds number 91.5×10~6/m,half wedge angle 5°,and nose radii ranging from 2.54 mm to 15.24 mm.Two novel growth patterns of travelling waves are identified to compete,whose nature is the intersection of the energy gain of optimal and sub-optimal disturbances.Pattern A with large spanwise wavelengths has the signature of slow energy amplification over a long distance which concentrates in the entropy layer.By contrast,pattern B with relatively small spanwise wavelengths presents rapid transient growth inside the boundary layer.A systematic study is performed on the growth/attenuation mechanism of disturbance patterns and the effects of wall temperature and nose radius.Wall cooling is found to be an alternative control strategy aimed at nonmodal instabilities.The receptivity to slow acoustic waves is considered when the effect of bluntness is studied.An estimated amplitude response favorably reproduces the reversal-like phenomenon.The lift-up/Orr mechanism analysis provides an explanation of energy growth for nonmodal responses.
基金supported by the National Natural Science Foundation of China(No.62103014)。
文摘In practical combat scenarios,Hypersonic Glide Vehicles(HGV)face the challenge of evading Successive Pursuers from the Same Direction while satisfying the Homing Constraint(SPSDHC).To address this problem,this paper proposes a parameterized evasion guidance algorithm based on reinforcement learning.The three-player optimal evasion strategy is firstly analyzed and approximated by parametrization.The switching acceleration command of HGV optimal evasion strategy considering the upper limit of missile acceleration command is analyzed based on the optimal control theory.The terminal miss of HGV in the case of evading two missiles is analyzed,which means that the three-player optimal evasion strategy is a linear combination of two one-toone strategies.Then,a velocity control algorithm is proposed to increase the terminal miss by actively controlling the flight speed of the HGV based on the parametrized evasion strategy.The reinforcement learning method is used to implement the strategy in real time and a reward function is designed by deducing homing strategy for the HGV to approach the target,which ensures that the HGV satisfies the homing constraint.Experimental results demonstrate the feasibility and robustness of the proposed parameterized evasion strategy,which enables the HGV to generate maximum terminal miss and satisfy homing constraint when facing single or double missiles.
基金supported by the National Natural Science Foundation of China(Grant Nos.62473374,62403487 and U2441243).
文摘For the longitudinal midcourse guidance problem of a cruise-glide integrated hypersonic vehicle(CGHV),an analytical method based on optimal control theory is proposed.This method constructs a guidance dynamics model for such vehicles,using aerodynamic load as the control variable,and introduces a framework for solving the guidance laws.This framework unifies the design process of guidance laws for both the glide and cruise phases.By decomposing the longitudinal guidance task into position control and velocity control,and minimizing energy consumption as the objective function,the method provides an analytical solution for velocity control load through the calculation of costate variables.This approach requires only the current state and terminal state parameters to determine the guidance law solution.Furthermore,by transforming path constraints into aerodynamic load constraints and solving backwards to obtain the angle of attack,bank angle,and throttle setting,this method ensures a smooth transition from the glide phase to the cruise phase,guaranteeing the successful completion of the guidance task.Finally,the effectiveness and practicality of the proposed method are validated through case simulations and analysis.
基金supported by the National Natural Science Foundation of China (Grant No. 12302056)the Postdoctoral Fellowship Program of CPSF:GZC20233445。
文摘The precise characterization of hypersonic glide vehicle(HGV) maneuver laws in complex flight scenarios still faces challenges. Non-stationary changes in flight state due to abrupt changes in maneuver modes place high demands on the accuracy of modeling methods. To address this issue, a novel maneuver laws modeling and analysis method based on higher order multi-resolution dynamic mode decomposition(HMDMD) is proposed in this work. A joint time-space-frequency decomposition of the vehicle's state sequence in the complex flight scenario is achieved with the higher order Koopman assumption and standard multi-resolution dynamic mode decomposition, and an approximate dynamic model is established. The maneuver laws can be reconstructed and analyzed with extracted multi-scale spatiotemporal modes with clear physical meaning. Based on the dynamic model of HGV, two flight scenarios are established with constant angle of attack and complex maneuver laws, respectively. Simulation results demonstrate that the maneuver laws obtained using the HMDMD method are highly consistent with those derived from the real dynamic model, the modeling accuracy is better than other common modeling methods, and the method has strong interpretability.
文摘Hypersonic Glide Vehicles(HGVs)are advanced aircraft that can achieve extremely high speeds(generally over 5 Mach)and maneuverability within the Earth's atmosphere.HGV trajectory prediction is crucial for effective defense planning and interception strategies.In recent years,HGV trajectory prediction methods based on deep learning have the great potential to significantly enhance prediction accuracy and efficiency.However,it's still challenging to strike a balance between improving prediction performance and reducing computation costs of the deep learning trajectory prediction models.To solve this problem,we propose a new deep learning framework(FECA-LSMN)for efficient HGV trajectory prediction.The model first uses a Frequency Enhanced Channel Attention(FECA)module to facilitate the fusion of different HGV trajectory features,and then subsequently employs a Light Sampling-oriented Multi-Layer Perceptron Network(LSMN)based on simple MLP-based structures to extract long/shortterm HGV trajectory features for accurate trajectory prediction.Also,we employ a new data normalization method called reversible instance normalization(RevIN)to enhance the prediction accuracy and training stability of the network.Compared to other popular trajectory prediction models based on LSTM,GRU and Transformer,our FECA-LSMN model achieves leading or comparable performance in terms of RMSE,MAE and MAPE metrics while demonstrating notably faster computation time.The ablation experiments show that the incorporation of the FECA module significantly improves the prediction performance of the network.The RevIN data normalization technique outperforms traditional min-max normalization as well.
基金supported by the National Natural Science Foundation of China(12072090).
文摘This paper concentrates on addressing the hypersonic glide vehicle(HGV)tracking problem considering the high maneuverability and non-stationary heavy-tailed measurement noise without prior statistics in complicated flight environments.Since the interacting multiple model(IMM)filtering is famous with its ability to cover the movement property of motion models,the problem is formulated as modeling the non-stationary heavy-tailed measurement noise without any prior statistics in the IMM framework.Firstly,without any prior statistics,the Gaussian-inverse Wishart distribution is embedded in the improved Pearson type-VII(PTV)distribution,which can adaptively adjust the parameters to model the non-stationary heavytailed measurement noise.Besides,degree of freedom(DOF)parameters are surrogated by the maximization of evidence lower bound(ELBO)in the variational Bayesian optimization framework instead of fixed value to handle uncertain non-Gaussian degrees.Then,this paper analytically derives fusion forms based on the maximum Versoria fusion criterion instead of the moment matching approach,which can provide a precise approximation for the PTV mixture distribution in the mixing and output steps combined with the weight Kullback-Leibler average theory.Simulation results demonstrate the superiority and robustness of the proposed algorithm in typical HGVs tracking when the measurement noise without priori statistics is non-stationary.
基金supported by the National Natural Science Foundation of China(Grant Nos.12090030 and 12002261)National Postdoctoral Program for Innovative Talents,China(Grant No.BX20200267)the Fundamental Research Funds for the Central Universities,China(Grant No.xzy012024019)。
文摘During the re-entry of a hypersonic aircraft into the earth’s atmosphere,the surrounding air experiences dissociation,ionization,and other complex chemical phenomena due to extreme temperature by shock wave.To ensure thermal safety,the thermochemical non-equilibrium effects resulting from real-gas behavior should be taken into account.In this paper,the characteristics of a double-cone hypersonic laminar flow,including distributions of wall pressure,heat flux,and species dissociation are numerically analyzed with incoming enthalpy of 9.65-21.77 MJ/kg.The thermochemical non-equilibrium flow at different enthalpy and wall temperatures is performed with two-temperature model and Park’s seven chemical reaction model.It is found that the doublecone flow features complex shock-shock interactions to form triple points.The flow topology is further brought out from the analysis of streamlines.At the lowest incoming enthalpy with isothermal wall conditions,two foci points appear.While others highlight only one focal point.As the increment of incoming enthalpy,the heat flux and dissociation of nitrogen and oxygen also increase.An increasing wall temperature leads to a larger separation bubble and a lower value of heat flux and pressure peak,while massive dissociation occurs without obvious ionization under considered cases.
基金Supported by the Innovation Foundation of Aerospace Science and Technology(CASC200902)~~
文摘Active disturbance rejection controller（ADRC）uses tracking-differentiator（TD）to solve the contradiction between the overshoot and the rapid nature.Fractional order proportion integral derivative（PID）controller improves the control quality and expands the stable region of the system parameters.ADRC fractional order（ADRFO）PID controller is designed by combining ADRC with the fractional order PID and applied to reentry attitude control of hypersonic vehicle.Simulation results show that ADRFO PID controller has better control effect and greater stable region for the strong nonlinear model of hypersonic flight vehicle under the influence of external disturbance,and has stronger robustness against the perturbation in system parameters.
基金Supported by the National Natural Science Foundation of China(10972104)~~
文摘The vibration characteristics of transverse oscillation of an axially moving beam with high velocity is in- vestigated. The vibration equation and boundary conditions of the free-free axially moving beam are derived using Hamilton＇s principle. Furthermore, the linearized equations are set up based on Galerkinl s method for the ap- proximation solution. Finally, three influencing factors on the vibration frequency of the beam are considered： （1） The axially moving speed. The first order natural frequency decreases as the axial velocity increases, so there is a critical velocity of the axially moving beam. （2） The mass loss. The changing of the mass density of some part of the beam increases the beam natural frequencies. （3） The thermal effect.＇ The temperature increase will decrease the beam elastic modulus and induce the vibration frequencies descending.
文摘A parallel virtual machine （PVM） protocol based parallel computation of 3-D hypersonic flows with chemical non-equilibrium on hybrid meshes is presented. The numerical simulation for hypersonic flows with chemical non-equilibrium reactions encounters the stiffness problem, thus taking huge CPU time. Based on the domain decomposition method, a high efficient automatic domain decomposer for three-dimensional hybrid meshes is developed, and then implemented to the numerical simulation of hypersonic flows. Control equations are multicomponent N-S equations, and spatially discretized scheme is used by a cell-centered finite volume algorithm with a five-stage Runge-Kutta time step. The chemical kinetic model is a seven species model with weak ionization. A point-implicit method is used to solve the chemical source term. Numerical results on PC-Cluster are verified on a bi-ellipse model compared with references.
基金co-supported by the National Natural Science Foundation of China(No.12102343)the Key Program of the National Natural Science Foundation of China(No.U2013206)+1 种基金Shanghai Space Science and Technology Innovation Fund,China(No.SAST2020-072)the Fundamental Research Funds for the Central Universities,China(No.D5000210833)。
文摘Air-breathing hypersonic vehicle has great military and potential economic value due to its characteristics:high velocity,long range,quick response.Therefore,the development of hypersonic vehicle and its guidance and control technology are reviewed in this paper.Firstly,the development and classification of hypersonic vehicles around the world are summarized,and the geometric configuration and mission profile of typical air-breathing hypersonic vehicle are given.Secondly,the control difficulties of air-breathing hypersonic vehicle are introduced,including integrated design of engine and fuselage,static instability,strong nonlinearity,uncertain aerodynamic parameters,etc.According to its control requirements,the control methods considering external disturbance,fault-tolerant control methods,anti-saturation methods,and prescribed performance control methods considering transient performance constraints are summarized respectively.The classification and comparison of various control methods are given,and the frontiers of theoretical development are analyzed.Finally,considering the effects of composite disturbances,the design of terminal guidance law under multiple constraints is overviewed,including guidance law with angle constraint,velocity constraint,acceleration constraint and time constraint.Similarly,the classification of guidance law design methods under different constraints,their advantages as well as the future development trend and requirements are introduced.
基金supported by National Outstanding Youth Science Foundation(61125306)National Natural Science Foundation of Major Research Plan(91016004,61034002)+2 种基金Specialized Research Fund for the Doctoral Program of Higher Education of China(20110092110020)Open Fund of Key Laboratory of Measurement and Control of Complex Systems of Engineering(Southeast University)Ministry of Education(MCCSE2013B01)
基金supported by National Natural Science Foundation of China(61125306,61273092,61301035,61304018,and 61411130160)National HighTechnology Research and Development Program of China(2014AA051901)+4 种基金Tianjin Science and Technology Supporting Program(14JCQNJC05400)Research Innovation Program of Tianjin University(2013XQ0101)Hubei Science and Technology Supporting Program(XYJ2014000314)Science Foundation of China Supported by Science and Technology on Aircraft Control Laboratory(20125848004)China Post-doctoral Science Foundation(2014M561559)
文摘Designing re-entry space vehicles and high-speed aircraft requires special attention to the nonlinear thermoelastic and aerodynamic instability of their structural components. The thermal effects are important since temperature environment brings dramatic influences on the static and dynamic behaviors of flight structures in supersonic/hypersonic regimes and is likely to cause instability, catastrophic failure and oscillations resulting in structural failure due to fatigue. In order to understand the dynamic behaviors of these ＂hot＂ structures, a double-wedge lifting surface with combining freeplay and cubic structural nonlinearities in both plunging and pitching degrees-of-freedom operating in supersonic/hypersonic flight speed regimes has been analyzed. A third order piston theory aerodynamic is used to estimate the applied nonlinear unsteady aerodynamic loads. Also considered is the loss of torsional stiffness that may be incurred by lifting surfaces subject to axial stresses induced by aerodynamic heating. The aerodynamic heating effects are estimated based on the adiabatic wall temperature due to high speed airstreams. As a recently emerging technology, the active aerothermoelastic control is aimed at providing solutions to a large number of problems involving the aeronautical/aerospace flight vehicle structures. To prevent such damaging phenomena from occurring, an application of linear and nonlinear active control methods on both flutter boundary and post-flutter behavior has been fulfilled. In this paper, modeling issues as well as numerical simulation have been presented and pertinent conclusions outlined. It is evidenced that a serious loss of torsional stiffness may induce the dynamic instability; however active control can be used to expand the flutter boundary and convert unstable limit cycle oscillations （LCO） into the stable LCO and/or to shift the transition between these two states toward higher flight Mach numbers.
基金co-supported by the National Natural Science Foundation of China (No. 51536004)the Science Fund for Creative Research Groups of NSFC (No. 51621062)
文摘Hypersonic vehicles with turbojet, ramjet, and scramjet engines are expected to be widely applied to future transportation systems. Due to high-speed flight in the atmosphere, body outer surfaces suffer strong aerodynamic heating, and on the other hand, combustion chamber inter walls are under extremely high temperature and heat flux. Therefore, more efficient and stable active cooling technologies are required in hypersonic vehicles, such as regenerative cooling, film cooling, and transpiration cooling, as well as their combinations. This paper presents a comprehensive literature review on three active cooling methods, i.e., regenerative cooling, film cooling, and transpiration cooling, and deeply analyzes the mechanism of each cooling method, including the fluids flow, heat transfer, and thermal cracking characteristics of different hydrocarbon fuels in regenerative cooling,the heat transfer and flow mechanism of film cooling under supersonic mainstream conditions, and the heat transfer and flow mechanism of transpiration cooling.
基金co-supported by the National Natural Science Foundation of China(Nos.61273349,61203223)the Innovation Foundation of BUAA for Ph D Graduates(No.YWF-14-YJSY-013)
文摘Abstract This paper presents the novel use of the particle swarm optimization （PSO） to generate the end-to-end trajectory for hypersonic reentry vehicles in a quite simple formulation. The velocity- dependent bank angle profile is developed to reduce the search space of unknown parameters based on the constrained PSO algorithm. The path constraints are enforced by setting the fitness function to be infinite on condition that the particles violate the maximum allowable values. The PSO algo- rithm also provides a much easier means to satisfy the terminal conditions by adding penalty terms to the fitness function. Furthermore, the approximate reentry landing footprint is fast constructed by incorporating an interpolation model into the standardized bank angle profiles. Numerical sim ulations demonstrate that the PSO method is a feasible and flexible tool to generate the end-to-end trajectory and landing footprint for hypersonic reentry vehicles.
