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A novel stiffness optimization model of space telescopic boom based on locking mechanism

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Frontiers of Mechanical engineering 2024年第3期19卷 41-59页

作者： Kun XU Xinghan ZHUANG Zhou SU Qiuhong LIN Shouzhi REN Hang XIAO Xilun DING School of Mechanical engineering and Automation Beihang UniversityBeijing 100191China beijing Institute of spacecraft system engineering Beijing 100094China

The deployable telescopic boom,whose mass and stiffness play crucial roles,is extensively used in the design of space-deployable ***,the most existing optimal design that neglects the influence of the locking mechanisms in boom joints cannot raise the whole stiffness while reducing the boom *** tackle this challenge,a novel optimization model,which utilizes the arrangement of the locking mechanisms to achieve synchronous improvement of the stiffness and mass,is *** proposed optimization model incorporates a novel joint stiffness model developed based on an equivalent parallel mechanism that enables the consideration of multiple internal stiffness factors of the locking mechanisms and tubes,resulting in more accurate representations of the joint stiffness *** analysis shows that the proposed stiffness model achieves more than at least 11% improved accuracy compared with existing ***,case verification shows that the proposed optimization model can improve stiffness while effectively reducing mass,and it is applied in boom optimization design.

关键词： deployable telescopic boom locking mechanism stiffness model clearance error optimization model

Autonomous relative optical navigation based on unified modeling of external systematic errors

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Chinese Journal of Aeronautics 2024年第3期37卷 282-289页

作者： Dayi WANG Bowen SUN Maodeng LI Jiaxing LI Haiyin ZHOU beijing Institute of spacecraft system engineering Beijing 100191China College of Sciences National University of Defense TechnologyChangsha 410073China National Key Laboratory of Space Intelligent Control Beijing Institute of Control EngineeringBeijing 100191China

To solve the problem that external systematic errors of the optical camera cannot be fully estimated due to limited computing resources,a unified dimensionality reduction representation method for the external systematic errors of the optical camera is proposed,and autonomous relative optical navigation is *** camera translational and misalignment errors are converted into a three-dimensional rotation error,whose differential model can be established through specific attitude control and appropriate ***,the rotation error and the relative motion state are jointly estimated in an augmented Kalman filter *** with the traditional method that estimates the camera translational and misalignment errors,the proposed method reduces the computational complexity in that the estimated state dimension is ***,as demonstrated by numerical simulation,the estimation accuracy is improved significantly.

关键词： Unified model systematic errors Optical navigation Observability analysis Calibration

Effects of projectile parameters on the momentum transfer and projectile melting during hypervelocity impact

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Defence Technology（防务技术） 2024年第2期32卷 89-103页

作者： Wenjin Liu Qingming Zhang Renrong Long Zizheng Gong Ren Jiankang Xin Hu Siyuan Ren Qiang Wu Guangming Song State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China beijing Institute of spacecraft Environment engineering China Academy of Space TechnologyBeijing100094China

The effects of projectile/target impedance matching and projectile shape on energy,momentum transfer and projectile melting during collisions are investigated by numerical *** comparing the computation results with the experimental results,the correctness of the calculation and the statistical method of momentum transfer coefficient is *** shapes of aluminum,copper and heavy tungsten alloy projectiles striking aluminum,basalt,and pumice target for impacts up to 10 km/s are *** influence mechanism of the shape of the projectile and projectile/target density on the momentum transfer was *** an increase in projectile density and length-diameter ratio,the energy transfer time between the projectile and targets is *** projectile decelerates slowly,resulting in a larger cratering *** energy consumed by the projectile in the excavation stage increased,resulting in lower mass-velocity of ejecta and momentum transfer *** numerical simulation results demonstrated that for different projectile/target combinations,the higher the wave impedance of the projectile,the higher the initial phase transition velocity and the smaller the mass of phase *** results can provide theoretical guidance for kinetic impactor design and material selection.

关键词： Hypervelocity impact Energy partitioning Impact melting Momentum transfer

Channel Correlation Based User Grouping Algorithm for Nonlinear Precoding Satellite Communication system

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China Communications 2024年第1期21卷 200-214页

作者： Ke Wang Baorui Feng Jingui Zhao Wenliang Lin Zhongliang Deng Dongdong Wang Yi Cen Genan Wu School of Information and Communication engineering Beijing University of Posts and TelecommunicationsBeijing 100876China School of Information engineering Minzu University of ChinaBeijing 100081China Institute of spacecraft Application system engineering China Academy of Space TechnologyBeijing 100094China Academy for Network and Communications of CETC Science and Technology on Communication Networks LaboratoryShijiazhuang 050081China

Low Earth Orbit(LEO)multibeam satellites will be widely used in the next generation of satellite communication systems,whose inter-beam interference will inevitably limit the performance of the whole *** precoding such as Tomlinson-Harashima precoding(THP)algorithm has been proved to be a promising technology to solve this problem,which has smaller noise amplification effect compared with linear ***,the similarity of different user channels(defined as channel correlation)will degrade the performance of THP *** this paper,we qualitatively analyze the inter-beam interference in the whole process of LEO satellite over a specific coverage area,and the impact of channel correlation on Signal-to-Noise Ratio(SNR)of receivers when THP is *** user grouping algorithm is proposed based on the analysis of channel correlation,which could decrease the number of users with high channel correlation in each precoding group,thus improve the performance of ***,our algorithm is designed under the premise of co-frequency deployment and orthogonal frequency division multiplexing(OFDM),which leads to more users under severe inter-beam interference compared to the existing research on geostationary orbit satellites broadcasting *** results show that the proposed user grouping algorithm possesses higher channel capacity and better bit error rate(BER)performance in high SNR conditions relative to existing works.

关键词： channel correlation inter-beam interference multibeam satellite Tomlinson-Harashima precoding user grouping

Characteristics and close-range exploration methods of near- Earth asteroid 2016HO_(3)

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Astronomical Techniques and Instruments 2024年第1期1卷 42-51页

作者： He Zhang Fei Li Linzhi Meng Fuming Zeng Xiaoyu Jia Yu’ang Liu beijing Institute of spacecraft system engineering Beijing 100094China

The characteristics of asteroids are vital parameters for planning asteroid exploration *** characteristics have been explored in close range for some typical asteroids,and are summarized in the *** allows estimates of the characteristics of asteroid 2016HO_(3),the target of the first Chinese asteroid exploration mission,Tianwen *** obtain 80 characteristic parameters in 9 categories and analyze their impacts on the *** comparing three close-range exploration modes,we provide advantages and disadvantages of each,and propose suitable methods for the exploration of 2016HO_(3).Owing to the weak gravity and small size of 2016HO_(3),a combination of multiple hovering positions and active orbiting is recommended for scientific exploration.

关键词： Near-Earth asteroid 2016HO_(3) Tianwen 2 Close-range exploration Characteristics

Experimental and numerical flutter analysis of a folding fin with multiple asymmetric free-plays

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Chinese Journal of Aeronautics 2024年第5期37卷 332-348页

作者： Chenyu LIU Chao AN Changchuan XIE Xin ZHANG Lan YANG School of Aeronautic Science and engineering Beihang UniversityBeijing 100191China beijing Institute of Electronic system engineering Beijing 100854China beijing Institute of Astronautical systems engineering Beijing 100076China

Experimental folding fin models with an adjustable free-play are tested in a wind *** fin structure is modeled using the free-interface component mode synthesis method,and its free-play is modeled as four independent nonlinear springs with asymmetric stiffness.A nonplanar unsteady vortex-lattice method considering compressibility is employed to address nonlinear deformation and high subsonic *** spline interpolation is improved through projection and *** aeroelastic characteristics of folding fins with different free-play magnitudes,initial conditions and elastic-axis positions are analyzed using an established time-marching method because of its relatively small computation scale and high *** results show good consistency among the presented method,the wind tunnel test and the harmonic balance *** is a negative correlation between the critical speed of divergent motion and the ratio of the initial condition to the free-play *** either the free-play magnitude or the initial condition is extreme(tiny or vast),the system nonlinearity degenerates to ***,the flutter prevention design of a linear model can be applied to a nonlinear model,such as moving the elastic-axis position *** presented fin configuration exhibits an unstable limit cycle oscillation because the orders of coupled flutter modes do not change with variations in equivalent linear stiffness.

关键词： Free-play Limit cycle oscillation Flutter Component mode synthesis Vortex-lattice method

Time-varying parameters estimation with adaptive neural network EKF for missile-dual control system

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Journal of systems engineering and Electronics 2024年第2期35卷 451-462页

作者： YUAN Yuqi ZHOU Di LI Junlong LOU Chaofei School of Astronautics Harbin Institute of TechnologyHarbin 150001China beijing Institute of Electronic system engineering Beijing 100854China

In this paper, a filtering method is presented to estimate time-varying parameters of a missile dual control system with tail fins and reaction jets as control variables. In this method, the long-short-term memory(LSTM) neural network is nested into the extended Kalman filter(EKF) to modify the Kalman gain such that the filtering performance is improved in the presence of large model uncertainties. To avoid the unstable network output caused by the abrupt changes of system states,an adaptive correction factor is introduced to correct the network output online. In the process of training the network, a multi-gradient descent learning mode is proposed to better fit the internal state of the system, and a rolling training is used to implement an online prediction logic. Based on the Lyapunov second method, we discuss the stability of the system, the result shows that when the training error of neural network is sufficiently small, the system is asymptotically stable. With its application to the estimation of time-varying parameters of a missile dual control system, the LSTM-EKF shows better filtering performance than the EKF and adaptive EKF(AEKF) when there exist large uncertainties in the system model.

关键词： long-short-term memory(LSTM)neural network extended Kalman filter(EKF) rolling training time-varying parameters estimation missile dual control system

Design of integral sliding mode guidance law based on disturbance observer

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Journal of systems engineering and Electronics 2024年第1期35卷 186-194页

作者： ZHOU Jianping ZHANG Wenjie ZHOU Hang LI Qiang XIA Qunli School of Aerospace engineering Beijing Institute of TechnologyBeijing 100081China School of Informatic engineering Mianyang Techers’CollegeMianyang 62100China beijing Institute of Electronic system engineering Beijing 100854China beijing Institute of Space Long March Vehicle Beijing 100076China

With the increasing precision of guidance,the impact of autopilot dynamic characteristics and target maneuvering abilities on precision guidance is becoming more and more *** order to reduce or even eliminate the autopilot dynamic operation and the target maneuvering influence,this paper suggests a guidance system model involving a novel integral sliding mode guidance law(ISMGL).The method utilizes the dynamic characteristics and the impact angle,combined with a sliding mode surface scheme that includes the desired line-ofsight angle,line-of-sight angular rate,and second-order differential of the angular *** the same time,the evaluation scenario considere the target maneuvering in the system as the external disturbance,and the non-homogeneous disturbance observer estimate the target maneuvering as a compensation of the guidance *** proposed system’s stability is proven based on the Lyapunov stability *** simulations reveale that ISMGL effectively intercepted large maneuvering targets and present a smaller miss-distance compared with traditional linear sliding mode guidance laws and trajectory shaping guidance ***,ISMGL has a more accurate impact angle and fast convergence speed.

关键词： disturbance observer pilot dynamics integral sliding mode impact angle constraint maneuvering target

Investigations of the mechanical response of dummy HTPB propellant grain under ultrahigh acceleration overload conditions using onboard flight-test measurements

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Defence Technology（防务技术） 2024年第2期32卷 473-484页

作者： Yiming Zhang Ningfei Wang Weihua Ma Ran Wang Long Bai Yi Wu School of Aerospace engineering Beijing Institute of TechnologyBeijing 100081China beijing system Design Institute of Electro-mechanic engineering Beijing 100854China Xi'an Changfeng Research Institute of Mechanism and Electricity Xi'an 710065China

In this paper,to study the mechanical responses of a solid propellant subjected to ultrahigh acceleration overload during the gun-launch process,specifically designed projectile flight tests with an onboard measurement system were *** projectiles containing dummy HTPB propellant grains were successfully recovered after the flight tests with an ultrahigh acceleration overload value of 8100 *** onboard-measured time-resolved axial displacement,contact stress and overload values were successfully obtained and *** compression tests of the dummy HTPB propellant used in the gunlaunched tests were carried out at low and intermediate strain rates to characterize the propellant's dynamic properties.A linear viscoelastic constitutive model was employed and applied in finite-element simulations of the projectile-launching *** the launch process,the dummy propellant grain exhibited large deformation due to the high acceleration overload,possibly leading to friction between the motor case and propellant *** calculated contact stress showed good agreement with the experimental results,though discrepancies in the overall displacement of the dummy propellant grain were *** dynamic mechanical response process of the dummy propellant grain was analysed in *** results can be used to estimate the structural integrity of the analysed dummy propellant grain during the gun-launch process.

关键词： Gun-launched flight test Dummy HTPB propellant Onboard measurements Utrahigh overload Mechanical response