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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 system.There 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) theory.First,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 signal.Then,the ideal torque of the actuator is designed employing the I&I theory.The unfavorable oscillation of the fin is suppressed by making the output torque of the actuator track the ideal signal.The 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 range.The power required for the actuator does not exceed the power that can be provided by the commonly used aviation actuator.This 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 given.The 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 cases.Here,we study an 8×8 Green’s matrix directly.More 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 before.We 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

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

Dynamic modeling and beating phenomenon analysis of space robots with continuum manipulators

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Chinese Journal of Aeronautics 2022年第9期35卷 226-241页

作者： Jinzhao YANG Haijun PENG Jie ZHANG zhigang wu School of Aeronautics and Astronautics Dalian University of TechnologyDalian 116024China Department of Engineering Mechanics Dalian University of TechnologyDalian 116024China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian I16024China

Space robotics has been used extensively in complex space missions. Rigid-manipulator space robots may suffer from rigid-body collisions with targets. This collision is likely to cause damage to the space robot and the target. To overcome such a problem, a novel ContinuumManipulator Space Robot(CMSR) for performing on-orbit servicing missions is proposed in this paper. Compared with rigid-manipulator space robots, CMSRs are able to perform compliant operations and avoid rigid-body collisions with a target. The CMSR consists of two kinds of flexible components, including solar arrays and continuum manipulators. The elastic vibrations of these flexible components disturb the position and attitude of CMSRs. The beating phenomenon introduced by the energy transfer among these flexible components can cause damage to solar arrays.The complicated dynamic coupling poses enormous challenges in dynamic modeling and vibration analysis. The dynamic model for CMSRs is derived and the mechanism of the beating phenomenon is analyzed in this paper. Simulation results show that an obvious beating phenomenon occurs and the amplitude of the solar arrays increases significantly when the natural frequencies of two kinds of flexible components are close. A method is provided to avoid the beating phenomenon.

关键词： Continuum manipulators Dynamic model Solar arrays Space robots Vibration analysis

Novel orbit-attitude combination mode for solar power satellites to reduce mass and fuel

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Chinese Journal of Aeronautics 2022年第8期35卷 132-142页

作者： Qingjun LI Yi WEI zhigang wu Jianping JIANG School of Aeronautics and Astronautics Sun Yat-sen UniversityShenzhen 518107China School of Medical Information Engineering Jining Medical UniversityRizhao 276826China

Solar power satellite receives great attention because it can release the energy crisis and environmental problems in the future.However,the launch and maintenance costs are tremendous due to the large system mass and large fuel consumption to counteract space perturbations.To reduce mass and fuel,a novel quasi-Sun-pointing attitude in Sun-frozen orbit is proposed.The Sun-frozen orbit has a nonzero eccentricity vector that always points towards the Sun.The quasi-Sun-pointing attitude is a periodic solution of the Sun-pointing attitude angle.Although about 3%electricity must be given up because of the variation of Sun-pointing attitude angle,little control action is required to deal with the solar radiation pressure and gravity-gradient torque.The algorithm to obtain initial conditions is proposed.The influences of system parameters and structural flexibilities are studied.Simulation results reveal that the quasi-Sun-pointing attitude in Sunfrozen orbit dramatically reduce fuel consumption,the dry mass,and complexity of the control system.In addition,structural vibration is hardly induced by the gravity-gradient torque.Thus,the bending stiffness as well as the mass of the supporting structure can be reduced.

关键词： Gravity gradient torque Quasi-Sun-pointing attitude Solar radiation pressure Space solar power station Sun-frozen orbit

An Origami-Like Sheath of a Honeybee Tongue for Fluid Viscosity Sensing

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Journal of Bionic Engineering 2023年第6期20卷 2764-2773页

作者： Caiying Liao Jiangkun Wei Yichen Lan zhigang wu Chengpei Tang Jianing wu School of Aeronautics and Astronautics Shenzhen Campus of Sun Yat-Sen UniversityShenzhen518107China School of Advanced Manufacturing Shenzhen Campus of Sun Yat-Sen UniversityShenzhen518107China Shenzhen College of International Education Shenzhen518107China

Mechanoreceptors play a vital role for animals to sense and monitor environmental parameters,like flow speed,tactile resistance,and pressure.The hairy-structured trichoid sensillum,a common type of mechanoreceptor in insects,is generally non-motile,embedded in a socket connected with cuticular substrate.However,we discover that the trichoid sensilla on the tongue of western bees(Apis mellifera L.)is rotatable and can be actively maneuvered by bees.The trichoid sensilla together with the socket base are mounted on the origami-like sheath of the tongue,and can rotate outwards along with the deformation of the tongue sheath.We illustrate that the rotation of the tongue sensilla hairs can locally generate shear force in the liquid to sense the viscosity,which may facilitate bees to adjust their feeding strategies.The viscosity sensitivity of the rotatable trichoid sensilla based on the origami-like mechanism,according to our mechanical model,is 13 times greater than that of the fixed sensilla.In addition,our finite element analysis shows that strain would concentrate on the trichoid sensilla base when rotating in the liquid,which may structurally enhance its perception sensitivity.This study reports a new mechanism of active mechanoreceptors and may have implications for origami mechanisms with correlative functional components,especially for micro-robotic systems used in underwater viscosity sensing.

关键词： Honey bee Mechanoreceptor Active sense Liquid viscosity Origami

Mechanistic Analysis and Bio-inspired Applications for a Bidirectional Stiffness of a Water Snail Operculum

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Journal of Bionic Engineering 2023年第5期20卷 1930-1941页

作者： Ke Xu Xiaoming Xu Qi Yang Jianing wu zhigang wu Jinzhao Yang School of Aeronautics and Astronautics Sun Yat-Sen UniversityShenzhen518107China Shenzhen Key Laboratory of Intelligent Microsatellite Constellation Shenzhen Campus of Sun Yat-Sen UniversityShenzhen518107China School of Engineering and Technology China University of Geosciences(Beijing)Beijing100083China School of Advanced Manufacturing Sun Yat-Sen UniversityShenzhen518107China

The water snail Pomacea canaliculata retracts the discoidal and multi-layered operculum to protect the soft body from being attacked by predators,and releases it when threats lifted.However,the duration of the operculum retraction is usually less than that of the operculum protraction.In this paper,we elucidate the biological compliant mechanism of the operculum.By using confocal laser scanning microscopy,we find that the operculum has compliant sandwiched layers between hard layers.The layered structure results in a compliant mechanism with a bidirectional stiffness for the locking and unlocking processes of the operculum.A mathematical model is derived to rationalize the bidirectional stiffness mechanism of the operculum.In addition,we carry out the experiments on the locking and unlocking processes.The experimental results show that the locking tension is about two-fifths of the unlocking tension of the operculum.Moreover,based on the mechanical properties of the operculum with the layered structure,we designed an operculum-inspired structure,which may have a variety of potential applications in combined driving patterns.

关键词： Water snail Operculum Multi-layered structure Bidirectional stiffness Compliant mechanism

H_(∞) control for a networked Markovian jump system subject to data packet loss based on the observer

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IET Cyber-Systems and Robotics 2022年第1期4卷 3-14页

作者： Yanfeng Wang Xiaoyue Sun Ping He zhigang wu School of Mechanical and Electrical Engineering Suqian UniversitySuqianChina School of Engineering Huzhou UniversityHuzhouChina College of Engineering Huazhong Agricultural UniversityWuhanChina School of Energy and Mechanical Engineering Jiangxi University of Science and TechnologyNanchangChina

This study researches the H_(∞) control issue for a networked Markovian jump system with data packet loss occurring not only in the channel from sensor to controller but also in the channel from controller to actuator via an observer.The mathematical model for the closed‐loop networked Markovian jump system with data packet loss is established.The necessary and sufficient conditions for the closed‐loop system to be stochastically stable are derived.The design approach of the controller and the minimal performance index of the external disturbance suppression are also given in the case that the transition possi-bilities of the system modes and the data packet loss are both partially unavailable.Finally,two numerical examples are used to illustrate the effectiveness of the proposed method.

关键词： data packet loss Markovian jump system networked control system observer

Dynamic degradation patterns of porous polycaprolactone/β-tricalcium phosphate composites orchestrate macrophage responses and immunoregulatory bone regeneration

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Bioactive Materials 2023年第3期21卷 595-611页

作者： Hao wu Xinghui Wei Yichao Liu Hui Dong Zhen Tang Ning Wang Shusen Bao zhigang wu Lei Shi Xiongfei Zheng Xiaokang Li Zheng Guo Department of Orthopaedics Tangdu HospitalFourth Military Medical UniversityXi’anShaanxi710038PR China Department of Orthopaedics Xijing HospitalFourth Military Medical UniversityXi’anShaanxi710032PR China Department of Orthopaedics The 63750 Hospital of People’s Liberation ArmyXi’anShaanxi710038PR China State Key Laboratory of Robotics Shenyang Institute of AutomationChinese Academy of SciencesShenyangLiaoning110000PR China

Biodegradable polycaprolactone/β-tricalcium phosphate(PT)composites are desirable candidates for bone tissue engineering applications.A higherβ-tricalcium phosphate(TCP)ceramic content improves the mechanical,hydrophilic and osteogenic properties of PT scaffolds in vitro.Using a dynamic degradation reactor,we estab-lished a steady in vitro degradation model to investigate the changes in the physio-chemical and biological properties of PT scaffolds during degradation.PT46 and PT37 scaffolds underwent degradation more rapidly than PT scaffolds with lower TCP contents.In vivo studies revealed the rapid degradation of PT(PT46 and PT37)scaffolds disturbed macrophage responses and lead to bone healing failure.Macrophage co-culture assays and a subcutaneous implantation model indicated that the scaffold degradation process dynamically affected macro-phage responses,especially polarization.RNA-Seq analysis indicated phagocytosis of the degradation products of PT37 scaffolds induces oxidative stress and inflammatory M1 polarization in macrophages.Overall,this study reveals that the dynamic patterns of biodegradation of degradable bone scaffolds highly orchestrate immune responses and thus determine the success of bone regeneration.Therefore,through evaluation of the biological effects of biomaterials during the entire process of degradation on immune responses and bone regeneration are necessary in order to develop more promising biomaterials for bone regeneration.

关键词： Polycaprolactone/β-TCP Dynamic degradation Macrophage response Bone healing