Pub Date : 2024-08-24DOI: 10.1016/j.ast.2024.109490
The control surface buzz may occur when the aircraft cruise at transonic Mach numbers, which would may lead to flight accidents. Transonic buzz could be a problem in aircraft design. The triggering of transonic buzz has been investigated in the previous publications. It is essentially a single degree of freedom flutter caused by the coupling of one structural mode and one pre-instability flow mode, thus, type A/B buzz usually occurs close to the buffet onset. With this mechanism, the buzz can be suppressed by improving the flow stability and buffet onset. Three buffet passive control techniques are applied to test the suppression effect on transonic buzz. The relationship between the flow stability and buzz onset is studied to verify the mechanism of buzz. CFD simulation and global stability analysis are applied to compute the flow stability with and without control techniques. Results show that, three control techniques can improve the flow stability and postpone the buffet onset. Meanwhile the buzz can be effectively suppressed. With the aeroelastic ROM and the root loci method, the coupling process between the structural mode and the controlled flow modes are revealed, indicating the buzz suppression effects are positively correlated with its improvement of the flow stability with control. This study can help to understand the mechanism of buzz deeply and propose the new thought of buzz suppression.
当飞机以跨音速马赫数巡航时,可能会出现控制面嗡嗡声,这可能会导致飞行事故。跨音速嗡嗡声可能是飞机设计中的一个问题。之前的出版物已经对跨音速嗡嗡声的诱发因素进行了研究。它本质上是由一种结构模式和一种预失稳流动模式耦合引起的单自由度扑动,因此,A/B 型嗡嗡声通常发生在缓冲开始的附近。利用这种机制,可以通过改善流动稳定性和缓冲区起始点来抑制嗡嗡声。我们采用了三种缓冲区被动控制技术来测试对跨音速嗡嗡声的抑制效果。研究了流动稳定性与嗡嗡声发生之间的关系,以验证嗡嗡声的机理。应用 CFD 仿真和全局稳定性分析计算了采用和未采用控制技术时的流动稳定性。结果表明,三种控制技术都能提高流动稳定性,推迟嗡嗡声的发生。同时,嗡嗡声也能得到有效抑制。通过气动弹性 ROM 和根定位法,揭示了结构模态与受控流动模态之间的耦合过程,表明嗡嗡声抑制效果与其受控流动稳定性的改善呈正相关。该研究有助于深入理解嗡嗡声的机理,并提出了抑制嗡嗡声的新思路。
{"title":"On the mechanism of transonic buzz passive suppression with global stability analysis","authors":"","doi":"10.1016/j.ast.2024.109490","DOIUrl":"10.1016/j.ast.2024.109490","url":null,"abstract":"<div><p>The control surface buzz may occur when the aircraft cruise at transonic Mach numbers, which would may lead to flight accidents. Transonic buzz could be a problem in aircraft design. The triggering of transonic buzz has been investigated in the previous publications. It is essentially a single degree of freedom flutter caused by the coupling of one structural mode and one pre-instability flow mode, thus, type A/B buzz usually occurs close to the buffet onset. With this mechanism, the buzz can be suppressed by improving the flow stability and buffet onset. Three buffet passive control techniques are applied to test the suppression effect on transonic buzz. The relationship between the flow stability and buzz onset is studied to verify the mechanism of buzz. CFD simulation and global stability analysis are applied to compute the flow stability with and without control techniques. Results show that, three control techniques can improve the flow stability and postpone the buffet onset. Meanwhile the buzz can be effectively suppressed. With the aeroelastic ROM and the root loci method, the coupling process between the structural mode and the controlled flow modes are revealed, indicating the buzz suppression effects are positively correlated with its improvement of the flow stability with control. This study can help to understand the mechanism of buzz deeply and propose the new thought of buzz suppression.</p></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142122462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-24DOI: 10.1016/j.ast.2024.109524
Three‒dimensional atomization field of the radial annular slot type liquid‒liquid pintle injector under different total momentum ratio (TMR) is simulated based on the volume of fluid to discrete particle model (VOF to DPM) method and the octree adaptive mesh refinement (AMR). The typical spray morphology of the injector is obtained, the variation of spray angle, breakup length of liquid film, amplitude of disturbance waves before liquid film breaking and its causes are analyzed. The results show that the injector can form a hollow conical spray during operation, and there are two recirculation zones near the inner surface of liquid film. According to the characteristics of the spray morphology, the spray can be divided into four areas: undisturbed liquid film, disturbed liquid film, fluctuating breakup zone and small droplets accumulation zone. The simulated spray angle is close to the model proposed by Heister when TMR is smaller than 0.6 and is close to the model proposed by Boettcher when TMR exceeds 0.6, with the maximum relative error of 9.5%. TMR has little influence on the amplitude of disturbance waves before liquid film breaking, while the breakup length of liquid film increases at first and then decreases with the increase of TMR. The breakup length is relatively large when TMR is close to 1, within the range of 20∼22 mm, while it is relatively small when TMR is far away from 1, within the range of 12∼15mm.
{"title":"Multi‒scale numerical investigations on the atomization performance of liquid‒liquid pintle injector","authors":"","doi":"10.1016/j.ast.2024.109524","DOIUrl":"10.1016/j.ast.2024.109524","url":null,"abstract":"<div><p>Three‒dimensional atomization field of the radial annular slot type liquid‒liquid pintle injector under different total momentum ratio (TMR) is simulated based on the volume of fluid to discrete particle model (VOF to DPM) method and the octree adaptive mesh refinement (AMR). The typical spray morphology of the injector is obtained, the variation of spray angle, breakup length of liquid film, amplitude of disturbance waves before liquid film breaking and its causes are analyzed. The results show that the injector can form a hollow conical spray during operation, and there are two recirculation zones near the inner surface of liquid film. According to the characteristics of the spray morphology, the spray can be divided into four areas: undisturbed liquid film, disturbed liquid film, fluctuating breakup zone and small droplets accumulation zone. The simulated spray angle is close to the model proposed by Heister when TMR is smaller than 0.6 and is close to the model proposed by Boettcher when TMR exceeds 0.6, with the maximum relative error of 9.5%. TMR has little influence on the amplitude of disturbance waves before liquid film breaking, while the breakup length of liquid film increases at first and then decreases with the increase of TMR. The breakup length is relatively large when TMR is close to 1, within the range of 20∼22 mm, while it is relatively small when TMR is far away from 1, within the range of 12∼15mm.</p></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142095775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-24DOI: 10.1016/j.ast.2024.109440
The catalytic reactor, which plays a pivotal role in the novel aircraft fuel tank green inerting system, encounters complex and alternating inlet boundary conditions. In this study, a transient theoretical model of the catalytic reactor was established and solved through programming, and its accuracy was verified through self-built experimental setups. The dynamic performance of the catalytic reactor and the impact of operational parameters were investigated. Additionally, a method for determining the operational range of the catalytic reactor was proposed. The results indicate that the bed temperature gradually increases to 370°C along the axial direction as the reaction progresses over time. In addition, the concentrations of fuel vapor and oxygen gradually decrease along the axial direction or with time, while achieving a fuel vapor conversion rate of 70.13% under design conditions. The promotion of catalytic reactions can be achieved by lowering the inlet gas velocity, elevating temperature, or increasing the concentrations of fuel vapor and oxygen. However, the bed's maximum temperature may surpass the self-ignition temperature of fuel vapor by 425°C. A novel indicator for oxygen consumption rate is proposed, which should be comprehensively evaluated in conjunction with the conversion rate to determine the performance of catalytic reactors. Moreover, increasing the reactor diameter can enhance both conversion rate and oxygen consumption rate. Pressure drop is detrimental to the catalytic reaction, therefore, high altitude and low-pressure conditions should be considered as the standard for reactor design. Meanwhile, this paper proposes a theoretical model to determine the operational range of the catalytic reactor based on criteria such as suitable catalytic efficiency and flight temperature. The research findings presented in this study provide a solid theoretical foundation for optimizing catalytic reactor design, thereby significantly promoting the application of green inerting systems.
{"title":"Study on the performance of catalytic reactor for aircraft fuel tank inerting system","authors":"","doi":"10.1016/j.ast.2024.109440","DOIUrl":"10.1016/j.ast.2024.109440","url":null,"abstract":"<div><p>The catalytic reactor, which plays a pivotal role in the novel aircraft fuel tank green inerting system, encounters complex and alternating inlet boundary conditions. In this study, a transient theoretical model of the catalytic reactor was established and solved through programming, and its accuracy was verified through self-built experimental setups. The dynamic performance of the catalytic reactor and the impact of operational parameters were investigated. Additionally, a method for determining the operational range of the catalytic reactor was proposed. The results indicate that the bed temperature gradually increases to 370°C along the axial direction as the reaction progresses over time. In addition, the concentrations of fuel vapor and oxygen gradually decrease along the axial direction or with time, while achieving a fuel vapor conversion rate of 70.13% under design conditions. The promotion of catalytic reactions can be achieved by lowering the inlet gas velocity, elevating temperature, or increasing the concentrations of fuel vapor and oxygen. However, the bed's maximum temperature may surpass the self-ignition temperature of fuel vapor by 425°C. A novel indicator for oxygen consumption rate is proposed, which should be comprehensively evaluated in conjunction with the conversion rate to determine the performance of catalytic reactors. Moreover, increasing the reactor diameter can enhance both conversion rate and oxygen consumption rate. Pressure drop is detrimental to the catalytic reaction, therefore, high altitude and low-pressure conditions should be considered as the standard for reactor design. Meanwhile, this paper proposes a theoretical model to determine the operational range of the catalytic reactor based on criteria such as suitable catalytic efficiency and flight temperature. The research findings presented in this study provide a solid theoretical foundation for optimizing catalytic reactor design, thereby significantly promoting the application of green inerting systems.</p></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142048875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-23DOI: 10.1016/j.ast.2024.109516
Field-emission electric propulsion is an electrostatic space electric propulsion technology that offers various advantageous features including efficient design, high specific impulse, and versatile thrust capabilities ranging from micro-Newton to milli-Newton levels. These characteristics make this type of propulsion a promising technology for small satellite platforms, enabling precise attitude control, orbit maintenance, and de-orbiting through ionization and acceleration of a liquid metal propellant. The growing demand for small propulsion systems in CubeSat platforms has spurred significant progress in modeling and characterizing field emission electric propulsion thrusters to enhance their overall performance. However, little study has been conducted to investigate the effect of geometric configurations on electric fields or expelled ion trajectories for design optimization. In this study, multi-objective design optimization is performed by incorporating electrostatic simulation coupled with an analytical performance model into evolutionary algorithms based on prediction from surrogate modeling, aiming to optimize the thruster emission design to maximize thruster performance. Physical insights into the key design factors influencing the performance of field emission electric propulsion have been gained by probing into the interaction between ion particles and electric field behavior within the thruster. It has been found that the length of the emitter tip has a significant effect on plume divergence, i.e., a longer emitter tip under the influence of electric field at higher emitter current tends to result in lower initial acceleration of emitted ions and subsequently wider spread or divergence of the ion beam. A shorter emitter tip, on the other hand, generates a sharper E-field gradient, resulting in a more focused and narrower ion beam. Additionally, sensitivity analysis has identified the mass flow rate and potential distributions as the most influential design factors on performance due to the active roles they play in the performance generation process.
{"title":"Multi-objective design optimization and physics-based sensitivity analysis of field emission electric propulsion for CubeSat platforms","authors":"","doi":"10.1016/j.ast.2024.109516","DOIUrl":"10.1016/j.ast.2024.109516","url":null,"abstract":"<div><p>Field-emission electric propulsion is an electrostatic space electric propulsion technology that offers various advantageous features including efficient design, high specific impulse, and versatile thrust capabilities ranging from micro-Newton to milli-Newton levels. These characteristics make this type of propulsion a promising technology for small satellite platforms, enabling precise attitude control, orbit maintenance, and de-orbiting through ionization and acceleration of a liquid metal propellant. The growing demand for small propulsion systems in CubeSat platforms has spurred significant progress in modeling and characterizing field emission electric propulsion thrusters to enhance their overall performance. However, little study has been conducted to investigate the effect of geometric configurations on electric fields or expelled ion trajectories for design optimization. In this study, multi-objective design optimization is performed by incorporating electrostatic simulation coupled with an analytical performance model into evolutionary algorithms based on prediction from surrogate modeling, aiming to optimize the thruster emission design to maximize thruster performance. Physical insights into the key design factors influencing the performance of field emission electric propulsion have been gained by probing into the interaction between ion particles and electric field behavior within the thruster. It has been found that the length of the emitter tip has a significant effect on plume divergence, <em>i.e.,</em> a longer emitter tip under the influence of electric field at higher emitter current tends to result in lower initial acceleration of emitted ions and subsequently wider spread or divergence of the ion beam. A shorter emitter tip, on the other hand, generates a sharper E-field gradient, resulting in a more focused and narrower ion beam. Additionally, sensitivity analysis has identified the mass flow rate and potential distributions as the most influential design factors on performance due to the active roles they play in the performance generation process.</p></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142083090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-23DOI: 10.1016/j.ast.2024.109508
The study presented is part of the H2020 CS2 European project VENUS, which investigates methodologies and tools to enable a concurrent design approach for both the aerodynamics and aeroacoustics of aircraft employing Distributed Electric Propulsion (DEP). Specifically, a 3D wing model, featuring a flap and powered by three electric motor-driven propellers, underwent a comprehensive testing campaign in the large-scale, low-speed, acoustically-treated Wind Tunnel (WT) of Pininfarina, Turin (Italy). A wide range of parameters was systematically varied and studied, including the blade pitch angle, the angle of attack, flap configurations for take-off and landing, phase shifts between propellers, and different relative distances both between the propellers themselves and with respect to the wing body. The experimental tests comprise both measurements of acoustics, such as beamforming and directivity analysis, and aerodynamics, through forces and wall pressure characteristics for the different DEP geometries. The main objective of this research is to identify potential optimal DEP configurations based on the WT test results which provided the aerodynamic and aeroacoustic performances exploited by each DEP solution. More specifically, it was found that the geometric arrangement with the propellers positioned closest to the wing and with non-overlapping rotor discs offers the best compromise between aerodynamic and aeroacoustic characteristics.
这项研究是 H2020 CS2 欧洲项目 "VENUS "的一部分,该项目研究方法和工具,以便对采用分布式电力推进(DEP)的飞机的空气动力学和气动声学进行同步设计。具体而言,在意大利都灵宾尼法利纳公司的大型低速声学风洞(WT)中,对以襟翼为特征、由三个电动马达驱动的螺旋桨提供动力的三维机翼模型进行了全面测试。对各种参数进行了系统的变化和研究,包括叶片俯仰角、攻角、起飞和着陆时的襟翼配置、螺旋桨之间的相移以及螺旋桨本身之间和相对于翼身的不同相对距离。实验测试包括声学测量(如波束成形和指向性分析)和空气动力学测量(通过不同 DEP 几何结构的力和壁压特性)。这项研究的主要目的是根据 WT 测试结果确定潜在的最佳 DEP 配置,这些测试结果提供了每个 DEP 解决方案所利用的空气动力学和空气声学性能。更具体地说,研究发现,螺旋桨位置最靠近机翼、转子圆盘不重叠的几何布置是气动特性和气动声学特性之间的最佳折衷方案。
{"title":"Aerodynamic and aeroacoustic experimental investigation of a three propellers DEP configuration","authors":"","doi":"10.1016/j.ast.2024.109508","DOIUrl":"10.1016/j.ast.2024.109508","url":null,"abstract":"<div><p>The study presented is part of the H2020 CS2 European project VENUS, which investigates methodologies and tools to enable a concurrent design approach for both the aerodynamics and aeroacoustics of aircraft employing Distributed Electric Propulsion (DEP). Specifically, a 3D wing model, featuring a flap and powered by three electric motor-driven propellers, underwent a comprehensive testing campaign in the large-scale, low-speed, acoustically-treated Wind Tunnel (WT) of Pininfarina, Turin (Italy). A wide range of parameters was systematically varied and studied, including the blade pitch angle, the angle of attack, flap configurations for take-off and landing, phase shifts between propellers, and different relative distances both between the propellers themselves and with respect to the wing body. The experimental tests comprise both measurements of acoustics, such as beamforming and directivity analysis, and aerodynamics, through forces and wall pressure characteristics for the different DEP geometries. The main objective of this research is to identify potential optimal DEP configurations based on the WT test results which provided the aerodynamic and aeroacoustic performances exploited by each DEP solution. More specifically, it was found that the geometric arrangement with the propellers positioned closest to the wing and with non-overlapping rotor discs offers the best compromise between aerodynamic and aeroacoustic characteristics.</p></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1270963824006394/pdfft?md5=3657db374a9e26758748a0229e515b3c&pid=1-s2.0-S1270963824006394-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142088842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-23DOI: 10.1016/j.ast.2024.109513
One of the significant challenges in supersonic combustion ramjet engines lies in effective mixing of the fuel, primarily due to the high momentum of supersonic inflow at the combustor. Among the various fluid phenomena associated with fuel mixing, it is well recognized that the interaction between the fuel-injection jet plume and oblique shock waves can significantly enhance mixing efficiency. However, the most suitable interaction for optimal mixing enhancement remains yet to be clarified. The present study conducts model-based optimization and data mining for shock-induced mixing enhancement of angled-slot injection in a two-dimensional scramjet combustor. Stochastic deep-learning flowfield prediction has been utilized to enable fast and reliable evaluations of a substantial number of designs. Prediction errors can be estimated without requiring correct data owing to uncertainty quantification techniques. Data mining and sensitivity analysis, coupled with flowfield prediction, have revealed the optimal shock interaction with the fuel jet plume characterized by a pronounced downstream recirculation region. The mechanism that drives mixing enhancement through this recirculation region has been discussed based on the results of optimization and sensitivity analysis. This study has yielded valuable insights for the future design of scramjet injectors. Furthermore, the effectiveness of the model-based design and analysis has been demonstrated through the present study, showcasing its potential for guiding future developments in scramjet technology.
{"title":"Optimization and data mining for shock-induced mixing enhancement inside scramjet using stochastic deep-learning flowfield prediction","authors":"","doi":"10.1016/j.ast.2024.109513","DOIUrl":"10.1016/j.ast.2024.109513","url":null,"abstract":"<div><p>One of the significant challenges in supersonic combustion ramjet engines lies in effective mixing of the fuel, primarily due to the high momentum of supersonic inflow at the combustor. Among the various fluid phenomena associated with fuel mixing, it is well recognized that the interaction between the fuel-injection jet plume and oblique shock waves can significantly enhance mixing efficiency. However, the most suitable interaction for optimal mixing enhancement remains yet to be clarified. The present study conducts model-based optimization and data mining for shock-induced mixing enhancement of angled-slot injection in a two-dimensional scramjet combustor. Stochastic deep-learning flowfield prediction has been utilized to enable fast and reliable evaluations of a substantial number of designs. Prediction errors can be estimated without requiring correct data owing to uncertainty quantification techniques. Data mining and sensitivity analysis, coupled with flowfield prediction, have revealed the optimal shock interaction with the fuel jet plume characterized by a pronounced downstream recirculation region. The mechanism that drives mixing enhancement through this recirculation region has been discussed based on the results of optimization and sensitivity analysis. This study has yielded valuable insights for the future design of scramjet injectors. Furthermore, the effectiveness of the model-based design and analysis has been demonstrated through the present study, showcasing its potential for guiding future developments in scramjet technology.</p></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142083056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-23DOI: 10.1016/j.ast.2024.109515
This paper investigates the optimal tracking control problem of free-floating space robots in the presence of non-ideal factors, such as model uncertainties and external disturbances. To address this issue, we first leverage the deep Koopman operator, facilitated with a deep neural network, to establish an offline formulation of a global linearization model for a micro-nano free-floating space robot. Based on the estimated linearization model, we then employ the model predictive control method for online optimization control, achieving a significantly reduced computational burden. Additionally, a decay factor is integrated into the model predictive control optimization objective function to balance the precision of joint angles tracking with the suppression of base satellite attitude disturbance. To further address the modeling inaccuracies and external disturbances, we incorporate a disturbance observer based on a radial basis function neural network for online compensation within the model predictive control framework. This augmentation enhances tracking precision and robustness. Several groups of simulation results are carried out to demonstrate the effectiveness of the proposed method, showing its capability of energy consumption, disturbance rejection and enhanced robustness. These highlight the potential of the proposed method to improve the control performance of free-floating space robots, even in the absence of a precise dynamic model.
{"title":"Deep Koopman-operator-based model predictive control for free-floating space robots with disturbance observer","authors":"","doi":"10.1016/j.ast.2024.109515","DOIUrl":"10.1016/j.ast.2024.109515","url":null,"abstract":"<div><p>This paper investigates the optimal tracking control problem of free-floating space robots in the presence of non-ideal factors, such as model uncertainties and external disturbances. To address this issue, we first leverage the deep Koopman operator, facilitated with a deep neural network, to establish an offline formulation of a global linearization model for a micro-nano free-floating space robot. Based on the estimated linearization model, we then employ the model predictive control method for online optimization control, achieving a significantly reduced computational burden. Additionally, a decay factor is integrated into the model predictive control optimization objective function to balance the precision of joint angles tracking with the suppression of base satellite attitude disturbance. To further address the modeling inaccuracies and external disturbances, we incorporate a disturbance observer based on a radial basis function neural network for online compensation within the model predictive control framework. This augmentation enhances tracking precision and robustness. Several groups of simulation results are carried out to demonstrate the effectiveness of the proposed method, showing its capability of energy consumption, disturbance rejection and enhanced robustness. These highlight the potential of the proposed method to improve the control performance of free-floating space robots, even in the absence of a precise dynamic model.</p></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142083057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-23DOI: 10.1016/j.ast.2024.109514
This paper addresses the safety-critical formation tracking of fixed-wing unmanned aerial vehicles, where both the velocity constraint and multiple leaders are taken into consideration. A hierarchical control strategy, consisting of a distributed observer and a formation controller, is elaborately constructed to achieve the desired configuration with the velocity in a safe range. First, a novel distributed observer is designed to estimate the formation error, which promises the practical fixed-time convergence of the estimation error despite unknown inputs of leaders and disturbances. Then, the velocity constraint is enforced through the forward invariance of a safety set, for which a robust control barrier function is carefully constructed considering the effect of disturbances. Further, a local formation controller is established by embedding the robust control barrier function into quadratic programming. Compared with existing results, the proposed controller is able to achieve the formation configuration while satisfying velocity safety, even in the presence of disturbances. Simulations are conducted to demonstrate the proposed method's capability in guaranteeing velocity constraint and stabilizing formation errors.
{"title":"Velocity-constrained distributed formation tracking of fixed-wing UAVs with multiple leaders","authors":"","doi":"10.1016/j.ast.2024.109514","DOIUrl":"10.1016/j.ast.2024.109514","url":null,"abstract":"<div><p>This paper addresses the safety-critical formation tracking of fixed-wing unmanned aerial vehicles, where both the velocity constraint and multiple leaders are taken into consideration. A hierarchical control strategy, consisting of a distributed observer and a formation controller, is elaborately constructed to achieve the desired configuration with the velocity in a safe range. First, a novel distributed observer is designed to estimate the formation error, which promises the practical fixed-time convergence of the estimation error despite unknown inputs of leaders and disturbances. Then, the velocity constraint is enforced through the forward invariance of a safety set, for which a robust control barrier function is carefully constructed considering the effect of disturbances. Further, a local formation controller is established by embedding the robust control barrier function into quadratic programming. Compared with existing results, the proposed controller is able to achieve the formation configuration while satisfying velocity safety, even in the presence of disturbances. Simulations are conducted to demonstrate the proposed method's capability in guaranteeing velocity constraint and stabilizing formation errors.</p></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142128802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-23DOI: 10.1016/j.ast.2024.109523
Tightly coupled SINS/BPNS (strapdown inertial navigation system/bionic polarization navigation system) integration has been proven to be a promising navigation tactic to substitute SINS/GNSS (global navigation satellite system) integration in GNSS-denied environments. However, the existing tightly coupled SINS/BPNS integrations lack SINS position correction and the reliable screening of BPNS measurements, leading to difficulty to complete navigation tasks. This paper presents an enhanced tightly coupled SINS/BPNS integration to correct both SINS position and attitude and conduct reliable measurement screening for BPNS. This method establishes a new measurement model by formulating the relationship between the SINS position error and angle of E-vector to effectively correct the SINS position. Based on the corrected SINS position, the solar position is calculated and further plugged in the measurement model, leading to improved accuracy. Further, based on the focal plane polarization camera, a mechanism of reliable measurement selection with two-level processing is developed and combined with the extended Kalman filter to improve the filtering robustness for tightly coupled SINS/BPNS integration. Results of simulations and experiments show that the proposed method not only can effectively correct SINS navigation information, but also can possess a strong robustness to exclude unreliable BPNS measurements, leading to enhanced navigation performance for tightly coupled SINS/BPNS integration.
紧密耦合的 SINS/BPNS(带下惯性导航系统/仿生偏振导航系统)集成已被证明是一种有前途的导航策略,可在全球导航卫星系统(GNSS)缺失的环境中替代 SINS/GNSS(全球导航卫星系统)集成。然而,现有的 SINS/BPNS 紧耦合集成缺乏 SINS 位置校正和 BPNS 测量的可靠筛选,导致难以完成导航任务。本文提出了一种增强型紧耦合 SINS/BPNS 集成方法,既能校正 SINS 位置和姿态,又能对 BPNS 进行可靠的测量筛选。该方法通过制定 SINS 位置误差与 E-vector 角度之间的关系,建立了一个新的测量模型,从而有效地校正 SINS 位置。根据校正后的 SINS 位置,计算出太阳位置,并进一步将其输入测量模型,从而提高测量精度。此外,在焦平面偏振相机的基础上,还开发了一种采用两级处理的可靠测量选择机制,并与扩展卡尔曼滤波器相结合,提高了 SINS/BPNS 紧密耦合集成的滤波鲁棒性。仿真和实验结果表明,所提出的方法不仅能有效修正 SINS 导航信息,而且具有很强的鲁棒性,能排除不可靠的 BPNS 测量,从而提高 SINS/BPNS 紧密耦合集成的导航性能。
{"title":"Reliable measurement selection mechanism-based tightly coupled inertial/bionic polarization integration with position correction","authors":"","doi":"10.1016/j.ast.2024.109523","DOIUrl":"10.1016/j.ast.2024.109523","url":null,"abstract":"<div><p>Tightly coupled SINS/BPNS (strapdown inertial navigation system/bionic polarization navigation system) integration has been proven to be a promising navigation tactic to substitute SINS/GNSS (global navigation satellite system) integration in GNSS-denied environments. However, the existing tightly coupled SINS/BPNS integrations lack SINS position correction and the reliable screening of BPNS measurements, leading to difficulty to complete navigation tasks. This paper presents an enhanced tightly coupled SINS/BPNS integration to correct both SINS position and attitude and conduct reliable measurement screening for BPNS. This method establishes a new measurement model by formulating the relationship between the SINS position error and angle of E-vector to effectively correct the SINS position. Based on the corrected SINS position, the solar position is calculated and further plugged in the measurement model, leading to improved accuracy. Further, based on the focal plane polarization camera, a mechanism of reliable measurement selection with two-level processing is developed and combined with the extended Kalman filter to improve the filtering robustness for tightly coupled SINS/BPNS integration. Results of simulations and experiments show that the proposed method not only can effectively correct SINS navigation information, but also can possess a strong robustness to exclude unreliable BPNS measurements, leading to enhanced navigation performance for tightly coupled SINS/BPNS integration.</p></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142122463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-23DOI: 10.1016/j.ast.2024.109519
Micro-vibration suppression is crucial for satellites to ensure high imaging performance of optical loads. Herein, an active-passive integrated actuator based on macro fiber composite for micro-vibration isolation is proposed and investigated. Integrated passive and active vibration suppression is achieved by arraying a composite laminated beam consisting of the stiffness layer, damping layer and macro fiber composite layer. A dominant-frequency-correction hysteresis modeling strategy is devised to describe the asymmetric and rate-dependent voltage-force hysteresis of the proposed actuator. By treating the correction as a disturbance, the voltage-force hysteresis is compensated in combination with an extended state observer. In order to achieve resonance suppression, a full-estimation-feedback controller featuring merely displacement response feedback is developed exploiting the estimation of the extended state observer as feedback. Simulation results verify that the full-estimation-feedback controller is capable of suppressing the resonance peak with weak adverse effects on the transmissibility in the isolation band. Finally, experiments are performed to identify the voltage-force hysteresis model and evaluate the vibration isolation performance. Periodic and sweep excitation test results demonstrate that in passive mode, the actuator has a small resonance frequency of 2.3 Hz and a wide isolation band starting from 3.5 Hz. With the full-estimation-feedback controller, the resonance peak is effectively suppressed using a single signal feedback, while maintaining excellent vibration attenuation within the isolation band. The proposed actuator provides a paradigm for the design of active-passive integration vibration isolators for broadband micro-vibration suppression, which holds significant promise in enhancing the effectiveness of current observation missions.
{"title":"An active-passive integrated actuator based on macro fiber composite for on-orbit micro-vibration isolation","authors":"","doi":"10.1016/j.ast.2024.109519","DOIUrl":"10.1016/j.ast.2024.109519","url":null,"abstract":"<div><p>Micro-vibration suppression is crucial for satellites to ensure high imaging performance of optical loads. Herein, an active-passive integrated actuator based on macro fiber composite for micro-vibration isolation is proposed and investigated. Integrated passive and active vibration suppression is achieved by arraying a composite laminated beam consisting of the stiffness layer, damping layer and macro fiber composite layer. A dominant-frequency-correction hysteresis modeling strategy is devised to describe the asymmetric and rate-dependent voltage-force hysteresis of the proposed actuator. By treating the correction as a disturbance, the voltage-force hysteresis is compensated in combination with an extended state observer. In order to achieve resonance suppression, a full-estimation-feedback controller featuring merely displacement response feedback is developed exploiting the estimation of the extended state observer as feedback. Simulation results verify that the full-estimation-feedback controller is capable of suppressing the resonance peak with weak adverse effects on the transmissibility in the isolation band. Finally, experiments are performed to identify the voltage-force hysteresis model and evaluate the vibration isolation performance. Periodic and sweep excitation test results demonstrate that in passive mode, the actuator has a small resonance frequency of 2.3 Hz and a wide isolation band starting from 3.5 Hz. With the full-estimation-feedback controller, the resonance peak is effectively suppressed using a single signal feedback, while maintaining excellent vibration attenuation within the isolation band. The proposed actuator provides a paradigm for the design of active-passive integration vibration isolators for broadband micro-vibration suppression, which holds significant promise in enhancing the effectiveness of current observation missions.</p></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142095773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}