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Active flutter suppression of nonlinear fin-actuator system via inverse system and immersion and invariance method

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Chinese Journal of Aeronautics 2024年第4期37卷 343-362页

作者： Jin LU zhigang wu Chao YANG Chinese Aeronautical Establishment Beijing 100029China School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China

Structural nonlinearities such as freeplay will affect the stability and even flight safety of the fin-actuator *** is a lack of a practical method for designing Active Flutter Suppression (AFS) control laws for nonlinear fin-actuator systems.A design method for the AFS controller of the nonlinear all-movable fin-electromechanical actuator system is established by combining the inverse system and the Immersion and Invariance (I&I) ***,the composite control law combining the inverse system principle and internal model control is used to offset the nonlinearity and dynamics of the actuator,so that its driving torque can follow the ideal ***,the ideal torque of the actuator is designed employing the I&I *** unfavorable oscillation of the fin is suppressed by making the output torque of the actuator track the ideal *** simulation results reveal that the proposed AFS method can increase the flutter speed of the nonlinear finactuator system with freeplay,and a set of controller parameters is also applicable for wider freeplay within a certain *** power required for the actuator does not exceed the power that can be provided by the commonly used aviation *** method can also resist a certain level of noise and external disturbance.

关键词： Aeroelasticity Active flutter suppression Fin-actuator system Freeplay Inverse system Immersion and invariance

Space-time estimates of the 3D bipolar compressible Navier-Stokes-Poisson system with unequal viscosities

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Science China Mathematics 2024年第5期67卷 1059-1084页

作者： zhigang wu Weike Wang Department of Mathematics Donghua UniversityShanghai 201620China School of Mathematical Sciences Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Frontier Science Center of Modern Analysis(CMA-Shanghai) Shanghai Jiao Tong UniversityShanghai 200240China

The space-time behavior for the Cauchy problem of the 3D compressible bipolar Navier-Stokes-Poisson(BNSP)system with unequal viscosities is *** space-time estimate of the electric field▽φ=▽(-△)^(-1)(n-Zρ)is the most important in deducing generalized Huygens’principle for the BNSP system and it requires proving that the space-time estimate of n-Zρonly contains the diffusion wave due to the singularity of the operator▽(-△)^(-1).A suitable linear combination of unknowns reformulating the original system into two small subsystems for the special case(with equal viscosities)in wu and Wang(2017)is crucial for both linear analysis and nonlinear estimates,especially for the space-time estimate of▽φ.However,the benefits from this reformulation will no longer exist in general ***,we study an 8×8 Green’s matrix *** importantly,each entry in Green’s matrix contains wave operators in the low-frequency part,which will generally produce Huygens’wave;as a result,one cannot achieve the space-time estimate of n-Zρthat only contains the diffusion wave as *** overcome this difficulty by taking a more detailed spectral analysis and developing new estimates arising from subtle cancellations in Green’s function.

关键词： Green's function bipolar Navier-Stokes-Poisson system unequal viscosities

Nonlinear aeroelastic analysis of a twin-tail boom UAV with rudder freeplay nonlinearities

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CHINESE JOURNAL OF AERONAUTICS 2024年第9期37卷 276-296页

作者： Bai, Liuyue wu, zhigang Yang, Chao Beihang Univ Sch Aeronaut Sci & Engn Beijing 100191 Peoples R China

The issue of nonlinear structural freeplays in aircraft has always been a significant concern. This study investigates the aeroelastic characteristics of a twin-tail boom Unmanned Aerial Vehicle (UAV) with simultaneous freeplay nonlinearity in its left and right rudders. A comprehensive Limit Cycle Oscillation (LCO) solution route is proposed for complex aircraft with multiple freeplays, which can consider both accuracy and efficiency. For the first time, this study reveals the unique LCO characteristics exhibited by twin-tail boom UAVs with rudder freeplays and provides simulations and explanations of interesting phenomena observed during actual flight. The governing equations are established using the free-interface component mode synthesis method, and the LCOs of the system are mainly solved through the improved time-domain numerical continuation method and frequency-domain numerical continuation method. Furthermore, the study investigates the influence of the left and right rudder freeplay size ratio on the LCO characteristics. The results demonstrate that the twin-tail boom UAV exhibits two stable LCO types: close and differing left and right rudder amplitudes. The proposed method successfully describes the complete LCO behaviors of the system. Overall, this study makes significant contributions to our understanding of the aeroelastic behavior of twin-tail boom UAVs with rudder freeplays. (c) 2024 Production and hosting by Elsevier Ltd. on behalf of Chinese Society of Aeronautics and Astronautics. This is an open access article under the CC BY-NC-ND license (http://***/ licenses/by-nc-nd/4.0/).

关键词： Aeroelasticity Freeplay nonlinearity Limit cycle oscillation Numerical continuation Component mode synthesis LIMIT-CYCLE OSCILLATION STRUCTURAL NONLINEARITIES CONTROL SURFACE BIFURCATION-ANALYSIS DYNAMIC-ANALYSIS FLUTTER AIRFOIL INTEGRATION SYSTEMS CONTINUATION

In Situ Reconfiguration of Assembling Pattern for Modular Continuum Robots

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Journal of Bionic Engineering 2024年第4期21卷 1695-1706页

作者： Jie Zhang Jiannan Cai Ke Ma Jinzhao Yang zhigang wu Haijun Peng Jianing wu School of Mechanical Engineering Dalian University of TechnologyDalian116024People’s Republic of China School of Advanced Manufacturing Sun Yat-Sen UniversityShenzhen518107People’s Republic of China School of Aeronautics and Astronautics Sun Yat-Sen UniversityShenzhen518107People’s Republic of China

Modular continuum robots possess significant versatility across various scenarios;however,conventional assembling methods typically rely on linear connection between *** limitation can impede the robotic interaction capabilities,especially in specific engineering ***,inspired by the assembling pattern between the femur and tibia in a human knee,we proposed a multidirectional assembling *** strategy encompasses linear,oblique,and orthogonal connections,allowing a two-module continuum robot to undergo in-situ reconfiguration into three distinct initial *** anticipate the final configuration resulting from diverse assembling patterns,we employed the positional formulation finite element framework to establish a mechanical model,and the theoretical results reveal that our customizable strategy can offer an effective route for robotic *** showcased diverse assembling patterns for coping with interaction *** experimental results indicate that our modular continuum robot not only reconfigures its initial profile in situ but also enables on-demand regulation of the final *** capabilities provide a foundation for the future development of modular continuum robots,enabling them to be adaptable to diverse environments,particularly in unstructured surroundings.

关键词： Assembling patterns Continuum robot In-situ reconfiguration Tensegrity structure Varying stiffness

Combination of High Yield Strength and Improved Ductility of 21Cr Lean Duplex Stainless Steel by Tailoring Cold Deformation and Low-Temperature Short-Term Aging

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Acta Metallurgica Sinica(English Letters) 2024年第4期37卷 695-702页

作者： Zhenghong Liu zhigang wu Ying Han Xiaolei Song Guoqing Zu Weiwei Zhu Xu Ran Key Laboratory of Advanced Structural Materials Ministry of EducationChangchun University of TechnologyChangchun130012China School of Materials Science and Engineering Changchun University of TechnologyChangchun130012China Jilin Province Key Laboratory of Advanced Materials Processing and Application for Rail Transit Changchun University of TechnologyChangchun130012China

Proper matching of cold-rolled deformation and low-temperature short-term aging can simultaneously enhance the strength and ductility of the lean duplex stainless steel. To investigate this, the microstructure evolution of cold-rolled and aging steels was observed by using scanning electron microscopy, transmission electron microscopy and electron backscattered diffraction. Additionally, the phase volume fraction was measured using X-ray diffraction. In this study, it was observed that the elongation of 21Cr lean duplex stainless steel significantly increased to 16.7% after undergoing moderate cold deformation (~ 40% reduction) and subsequent aging treatment at 550 ℃ for 30 min. Remarkably, the material still maintained a high yield strength of 1045 MPa. Such an excellent mechanical property was attributed to a unique microstructure combination of fine α'-martensite, twins, coarsened austenite resulting from partial martensite reverse transformation, and two-phase fine layered structure. The result of this study may open up new horizons for the alloy development in order to overcome the low ductility of cold-rolled high-strength lean duplex stainless steel.

关键词： Lean duplex stainless steel Cold rolling Aging Microstructure Mechanical properties Use our pre-submission checklist

基于半动态交通均衡的电动汽车充电负荷概率分布建模

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电网技术 2024年第2期48卷 640-649页

作者：朱峻良武志刚刘嘉宁华南理工大学电力学院广东省广州市510641 广东电网有限责任公司电力调度控制中心广东省广州市510600

传统电动汽车充电负荷建模通常采用对电动汽车个体进行抽样模拟的方式,未能从分析机理的角度描述电动汽车群体相互作用形成的宏观运行状态。为此,提出一种基于半动态交通均衡模型和组合荷电状态(combined states of the charge,CSOC)概... 详细信息

传统电动汽车充电负荷建模通常采用对电动汽车个体进行抽样模拟的方式,未能从分析机理的角度描述电动汽车群体相互作用形成的宏观运行状态。为此,提出一种基于半动态交通均衡模型和组合荷电状态(combined states of the charge,CSOC)概率计算的电动汽车充电负荷概率分布计算方法。首先,分析电动汽车的交通特性和充电特性,并提出一种可行路径集构建方法;然后,引入交通均衡理论进行电动汽车空间分布建模,建立考虑随机效用的半动态交通均衡模型,实现宏观交通流均衡分配。进一步地,从理论层面分析电动汽车群的荷电状态变化,建立基于CSOC的充电负荷概率分布计算模型。最后,分别在13节点路网和实际大路网中验证所提方法的有效性,并分析了电动汽车渗透率和路网结构对充电负荷概率分布的影响。

关键词：电动汽车半动态交通均衡组合荷电状态充电负荷建模概率模型

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融合空间细节与语义特征的指针式仪表双边图像分割网络

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激光与光电子学进展 2024年第8期61卷 362-369页

作者：朱耀晖吴志刚陈敏江西理工大学能源与机械工程学院江西南昌330013

针对指针式仪表的小目标图像分割特点以及现有方法存在的局限性,提出融合空间细节与语义特征的双边路深度学习主干网络BiUnet,用于指针式仪表图像分割。该网络以BiSeNet V2算法作为出发点,重新设计其语义支路、细节支路以及双边融合层... 详细信息

针对指针式仪表的小目标图像分割特点以及现有方法存在的局限性,提出融合空间细节与语义特征的双边路深度学习主干网络BiUnet,用于指针式仪表图像分割。该网络以BiSeNet V2算法作为出发点,重新设计其语义支路、细节支路以及双边融合层。首先,利用ConvNeXt卷积模块对细节支路进行调整和优化,提升算法对指针及刻度线边界细节的特征提取能力;其次,结合编码器-解码器U型结构能够融合不同尺度语义信息的优势对语义支路进行重新设计,提高语义支路对指针和刻度这类小目标的分割能力;最后,提出双引导拼接聚合层,用于更好地融合细节支路和语义支路特征。在自制仪表图像分割数据集上的消融实验证实了所提出的网络设计方案的有效性和可行性。在仪表数据集上与不同主干网络进行对比实验,实验结果表明,BiUnet对仪表的平均分割精度mIoU(mean intersection of union)达到了88.66%,相比于BiSeNet V2网络的80.02%提升8.64个百分点,并且这两种网络的分割精度均优于基于Transformer和纯卷积的常见主干网络。

关键词：指针式仪表双边路主干网络深度学习图像分割

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航天结构空间组装动力学与控制研究进展

力学进展 2024年第2期54卷 344-390页

作者：吴志刚蒋建平邬树楠李庆军王兴谭述君邓子辰中山大学航空航天学院工业装备结构分析优化与CAE软件全国重点实验室西北工业大学航空学院

空间组装是建造空间站、大型卫星天线、大口径空间望远镜、空间太阳能电站等大型和超大型航天结构的重要手段.然而,航天结构组装过程将面临构型增长、参数变化、轨道-姿态-结构耦合、接触碰撞等复杂的动力学与控制问题,给精准、高效、... 详细信息

空间组装是建造空间站、大型卫星天线、大口径空间望远镜、空间太阳能电站等大型和超大型航天结构的重要手段.然而,航天结构组装过程将面临构型增长、参数变化、轨道-姿态-结构耦合、接触碰撞等复杂的动力学与控制问题,给精准、高效、稳定完成组装任务带来挑战.本文介绍了大型航天结构的动力学建模方法、超大型航天结构特殊的动力学现象、航天结构空间组装过程的动力学建模研究现状;综述了航天结构在轨运行阶段的控制方法、空间组装过程的组装序列规划方法、姿态控制与振动抑制方法研究进展;总结了航天结构组装过程动力学与控制地面模拟试验中的重力卸载、缩比模型设计与试验、非线性与不确定性试验等关键技术.最后,面向未来千米量级超大型航天结构空间组装需求,针对组装过程中结构尺寸、质量和力学参数跃变等特性提出了当前研究工作中亟须解决的几类动力学与控制问题.

关键词：大型航天结构超大型航天结构航天器动力学航天器控制空间组装地面模拟试验

融合载体动力学特征的智能多源自主导航方法研究

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宇航学报 2024年第4期45卷 550-559页

作者：王巍孟凡琛徐小明初未萌吴志刚中国航天科技集团有限公司北京100048 北京航天控制仪器研究所北京100039 中山大学航空航天学院深圳518107

多源自主导航系统技术是新一代国家综合定位、导航与授时(PNT)体系下终端用户的重要技术发展方向。面向新一代健壮性综合PNT体系跨场景的导航任务,多源自主导航系统面临着智能化的迫切需求。针对复杂导航行为决策可信性问题,提出了融合... 详细信息

多源自主导航系统技术是新一代国家综合定位、导航与授时(PNT)体系下终端用户的重要技术发展方向。面向新一代健壮性综合PNT体系跨场景的导航任务,多源自主导航系统面临着智能化的迫切需求。针对复杂导航行为决策可信性问题,提出了融合载体动力学特征的智能多源自主导航基本概念,归纳了其实践中面临的主要科学问题,系统阐述了深度融合载体动力学特征与人工智能方法的多源自主导航理论框架与方法内涵,为智能多源自主导航系统的理论、方法及应用提供支撑。

关键词：国家综合PNT体系多源自主导航载体动力学特征可信性智能决策