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Gain self-scheduled H_∞ control for morphing aircraft in the wing transition process based on an LPV model

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Chinese Journal of Aeronautics 2013年第4期26卷 909-917页

作者： Yue Ting wang lixin Ai Junqiang School of Aeronautic Science and Engineering Beihang University The First Aircraft Design Institute of AVIC

This article investigates gain self-scheduled H 1 robust control system design for a tailless fold- ing-wing morphing aircraft in the wing shape varying process. During the wing morphing phase, the aircraft＇s dynamic response will be governed by time-varying aerodynamic forces and moments. Nonlinear dynamic equations of the morphing aircraft are linearized by using Jacobian linearization approach, and a linear parameter varying （LPV） model of the morphing aircraft in wing folding is obtained. A multi-loop controller for the morphing aircraft is formulated to guarantee stability for the wing shape transition process. The proposed controller uses a set of inner-loop gains to provide stability using classical techniques, whereas a gain self-scheduled H 1 outer-loop controller is devised to guarantee a specific level of robust stability and performance for the time-varying dynamics. The closed-loop simulations show that speed and altitude vary slightly during the whole wing folding process, and they converge rapidly after the process ends. This proves that the gain self-scheduled H 1 robust controller can guarantee a satisfactory dynamic performance for the morphing aircraft during the whole wing shape transition process. Finally, the flight control system＇s robustness for the wing folding process is verified according to uncertainties of the aerodynamic parameters in the nonlinear model.

关键词： Gain self-scheduled H 1 robust control Linear parameter varying Morphing aircraft Wing transition

Slippery Surface of Nepenthes alata Pitcher： The Role of Lunate Cell and Wax Crystal in Restricting Attachment Ability of Ant Camponotus japonicus Mayr

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Journal of Bionic Engineering 2016年第3期13卷 373-387页

作者： lixin wang Shiyun Dong Qiang Zhou College of Mechanical Engineering Hebei University of Science and Technology Shijiazhuang 050018 China National Key Laboratory for Remanufacturing Academy of Armord Forces Engineering Beijing 100072 China Department of Mechatronic Engineering China Agricultural Universing Beijing 100083 China

This study attempts to investigate how the slippery surface of Nepenthes alata pitchers restricts the attachment ability of ant Camponotus japonicus Mayr, via climbing behavior observation and friction force measurement. Ants exhibited ineffective climbing behaviors and rather small friction forces when attached to upward-oriented slippery surfaces, but opposite phenomena were shown when on inverted surfaces. Friction forces of intact, claw tip-removed and pad-destroyed ants were measured on intact and de-waxed slippery surfaces, exploring the roles of wax crystals and lunate cells in restricting ant＇s attachment. On downward-directed slippery surfaces, greater forces were exhibited by intact and pad-destroyed ants; on the two slippery sur- faces, pad-destroyed ants presented slightly smaller forces and clawless ants generated considerably smaller forces. Somewhat different force was provided by clawless ants on upward and downward oriented slippery surfaces, and slightly higher force was shown when ants climbed on wax-removed surface. Results indicate that the lunate cells contribute greatly to decrease the friction force, whereas the wax crystals perform a supplementary role. Mechanical analysis suggests that the directionally growing lunate cells possess a sloped structure that effectively prevents the claw＇s mechanical interlock, reducing the ant＇s attachment ability considerably. Our conclusion supports a further interpretation of slippery surface＇s anti-attachment mecha- nism, also provides theoretical reference to develop biomimetic slippery plate to trap agricultural insect.

关键词： biotribology Nepenthes alata pitcher slippery surface lunate cell wax crystal ant Camponotusjaponicus Mayr

Digital virtual flight testing and evaluation method for flight characteristics airworthiness compliance of civil aircraft based on HQRM

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Chinese Journal of Aeronautics 2015年第1期28卷 112-120页

作者： Liu Fan wang lixin Tan Xiangsheng School of Aeronautic Science and Engineering Beihang University

In order to incorporate airworthiness requirements for flight characteristics into the entire development cycle of electronic flight control system（EFCS） equipped civil aircraft, digital virtual flight testing and evaluation method based on handling qualities rating method（HQRM）is proposed. First, according to HQRM, flight characteristics airworthiness requirements of civil aircraft in EFCS failure states are determined. On this basis, digital virtual flight testing model,comprising flight task digitized model, pilot controlling model, aircraft motion and atmospheric turbulence model, is used to simulate the realistic process of a pilot controlling an airplane to perform assigned flight tasks. According to the simulation results, flight characteristics airworthiness compliance of the airplane can be evaluated relying on the relevant regulations for handling qualities（HQ） rating. Finally, this method is applied to a type of passenger airplane in a typical EFCS failure state, and preliminary conclusions concerning airworthiness compliance are derived quickly. The research results of this manuscript can provide important theoretical reference for EFCS design and actual airworthiness compliance verification of civil aircraft.

关键词： civil aircraft compliance preliminary verification pilot turbulence realistic passenger concerning

Dynamic characteristics analysis and flight control design for oblique wing aircraft

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Chinese Journal of Aeronautics 2016年第6期29卷 1664-1672页

作者： wang lixin Xu Zijian Yue Ting School of Aeronautics Science and Engineering Beihang University

The movement characteristics and control response of oblique wing aircraft(OWA) are highly coupled between the longitudinal and lateral-directional axes and present obvious nonlinearity. Only with the implementation of flight control systems can flying qualities be satisfied. This article investigates the dynamic modeling of an OWA and analyzes its dynamic ***, a flight control law based on model-reference dynamic inversion is designed and verified. Calculations and simulations show that OWA can be trimmed by rolling a bank angle and deflecting the triaxial control surfaces in a coordinated way. The oblique wing greatly affects longitudinal motion. The short-period mode is highly coupled between longitudinal and lateral motion,and the bank angle also occurs in phugoid mode. However, the effects of an oblique wing on lateral mode shape are relatively small. For inherent control characteristics, symmetric deflection of the horizontal tail will generate not only longitudinal motion but also a large rolling rate. Rolling moment and pitching moment caused by aileron deflection will reinforce motion coupling, but rudder deflection has relatively little effect on longitudinal motion. Closed-loop simulations demonstrate that the flight control law can achieve decoupling control for OWA and guarantee a satisfactory dynamic performance.

关键词： Control allocation Decoupling Dynamic characteristics Model-reference dynamic inversion Oblique wing aircraft

Sliding mode control design for oblique wing aircraft in wing skewing process

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Chinese Journal of Aeronautics 2019年第2期32卷 263-271页

作者： Ting YUE Zijian XU lixin wang Tong wang School of Aeronautic Science and Engineering Beihang University China Ship Development and Design Center

When the wing of Oblique Wing Aircraft(OWA) is skewed, the center of gravity, inertia and aerodynamic characteristics of the aircraft all significantly change, causing an undesirable flight dynamic response, affecting the flying qualities, and even endangering the flight safety. In this study,the dynamic response of an OWA in the wing skewing process is simulated, showing that the threeaxis movements of the OWA are highly coupled and present nonlinear characteristics during the wing skewing. As the roll control efficiency of the aileron decreases due to the shortened control arm in an oblique configuration, the all-moving horizontal tail is used for additional roll and the control allocation is performed based on minimum control energy. Given the properties of pitchroll-yaw coupling and control input and state coupling, and the difficulty of establishing an accurate aerodynamic model in the wing skewing process due to unsteady aerodynamic force, a multi-loop sliding mode controller is formulated by the time-scale separation method. The closed-loop simulation results show that the asymmetric aerodynamics can be balanced and that the velocity and altitude of the aircraft maintain stable, which means that a smooth transition is obtained during the OWA's wing skewing.

关键词： Decoupling Dynamic response Oblique wing aircraft Sliding mode control Wing skewing process

Helical Fiber Pull-out in Biological Materials

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Acta Mechanica Solida Sinica 2016年第3期29卷 245-256页

作者： lixin wang Yuhong Cui Qinghua Qin Hui wang Jianshan wang Tianjin Key Laboratory of Modern Engineering Mechanics & Department of Mechanics Tianjin University Research School of Engineering Australian National University Department of Engineering Mechanics Henan University of Technology

Many biological materials, such as wood and bone, possess helicoid microstructures at microscale, which can serve as reinforcing elements to transfer stress between crack surfaces and improve the fracture toughness of their composites. Failure processes, such as fiber/matrix inter- face debonding and sliding associated with pull-out of helical fibers, are responsible mainly for the high energy dissipation needed for the fracture toughness enhancement. Here we present systemic analyses of the pull-out behavior of a helical fiber from an elastic matrix via the finite element method （FEM） simulation, with implications regarding the underlying toughening mechanism of helicoid microstructures. We find that, through their uniform curvature and torsion, helical fibers can provide high pull-out force and large interface areas, resulting in high energy dissipation that accounts, to a large extent, for the high toughness of biological materials. The helicity of fiber shape in terms of the helical angle has significant effects on the force-displacement relationships as well as the corresponding energy dissipation during fiber pull-out.

关键词： biological materials helicoid microstructures fiber pull-out energy dissipation,toughness

Nepenthes pitchers:surface structure,physical property,anti-attachment function and potential application in mechanical controlling plague locust

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Chinese Science Bulletin 2014年第21期59卷 2513-2523页

作者： lixin wang Qiang Zhou College of Mechanical Engineering Hebei University of Science and Technology College of Engineering China Agricultural University

Pitchers plants of Nepenthes specie growing in infertile habitats have developed highly specialized apparatus for trapping and digesting arthropods to obtain sufficient growing *** pitchers are generally recognized by several distinguishably morphological zones,and different districts exhibit distinct functions in prey capturing,combined effect of the several zones results in great trapping *** prey ability of Nepenthes pitchers potentially inspires an idea for biomimetic development of slippery trapping plate used in controlling agricultural pests,especially plague *** this paper,we reviewed the recent researches of Nepenthes pitchers,including surface structures,physical properties,and antiattachment *** from this,combined with our latest studies on mechanical controlling plague locust,the potential application of Nepenthes pitchers as establishing biomimetic models utilized in creating trapping plate was addressed,and several corresponding aspects requiring to be paid attention to in near future were also highlighted.

关键词：机械控制表面结构猪笼草物理性质蝗虫应用鼠疫附着

Short Text Mining Framework with Specific Design for Operation and Maintenance of Power Equipment

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CSEE Journal of Power and Energy Systems 2021年第6期7卷 1267-1277页

作者： Huifang wang Ziquan Liu Yongjin Xu Xiaoxiong Wei lixin wang College of Electrical Engineering Zhejiang UniversityHangzhou 310027China Electric Power Research Institute of State Grid Zhejiang Electric Power Co. Ltd.Hangzhou 310014China

In order to recover the value of short texts in the operation and maintenance of power equipment,a short text mining framework with specific design is ***,the process of the short text mining framework is summarized,in which the functions of all the processing modules are ***,according to the characteristics of short texts in the operation and maintenance of power equipment,the specific design for each module is proposed,which adapts the short text mining framework to a practical ***,based on the framework with the specific designed modules,two examples in terms of defect texts are given to illustrate the application of short text mining in the operation and maintenance of power *** results of the examples show that the short text mining framework is suitable for operation and maintenance tasks for power equipment,and the specific design for each module is beneficial for the improvement of the application effect.

关键词： Machine learning natural language processing operation and maintenance power equipment short text mining

Suggestions for flying qualities requirements of autonomous control unmanned combat aerial vehicles

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Chinese Journal of Aeronautics 2023年第11期36卷 42-57页

作者： lixin wang Jin wang Junqiang AI Hailiang LIU Ting YUE School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China AVIC The First Aircraft Institute Xi’an 710089China

There is a lack of quantitative flying qualities assessment requirements for unmanned combat aerial *** mission-oriented flying qualities evaluation approach can make up for the deficiencies of existing flying qualities *** the control characteristics and mission requirements of autonomous control unmanned combat aerial vehicles,flying qualities assessment tasks are designed and performance standards are developed on the basis of manned aircraft flying qualities assessment *** sets of mathematical simulations are performed by varying the control law parameters to investigate the relationship between the control law parameter values,closed-loop aircraft system characteristics and flying qualities *** simulation results and closed-loop frequency domain analysis show that the existing flying qualities guidelines for manned aircraft are not fully applicable to the flying qualities assessment of autonomous control unmanned combat aerial *** is found that the combination of the bandwidth and the phase at the bandwidth frequency can define the flying qualities requirements of autonomous control unmanned aerial *** criterion boundaries of different levels are given,and the physical reasons for the formation of boundary are *** results can be applied to flying qualities assessment and design of flight control laws for autonomous control unmanned combat aerial vehicles.

关键词： Assessment task Autonomous control Bandwidth and phase Flying quality Unmanned Aerial Vehicle(UAV)