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Intelligent sequential multi-impulse collision avoidance method for non-cooperative spacecraft based on an improved search tree algorithm

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Chinese Journal of Aeronautics 2025年第4期 382-397页

作者： Xuyang CAO Xin NING Zheng WANG Suyi LIU Fei CHENG Wenlong LI Xiaobin LIAN School of Astronautics Northwestern Polytechnical University National Key Laboratory of Aerospace Flight Dynamics Northwestern Polytechnical University Unmanned System Research Institute Northwestern Polytechnical University National Key Laboratory of Unmanned Aerial Vehicle Technology Northwestern Polytechnical University Integrated Research and Development Platform of Unmanned Aerial Vehicle Technology Northwestern Polytechnical University Northwest Institute of Mechanical and Electrical Engineering Shanghai Institute of Satellite Engineering Shanghai Academy of Spaceflight Technology

The problem of collision avoidance for non-cooperative targets has received significant attention from researchers in recent years. Non-cooperative targets exhibit uncertain states and unpredictable behaviors, making collision avoidance significantly more challenging than that for space debris. Much existing research focuses on the continuous thrust model, whereas the impulsive maneuver model is more appropriate for long-duration and long-distance avoidance ***, it is important to minimize the impact on the original mission while avoiding noncooperative targets. On the other hand, the existing avoidance algorithms are computationally complex and time-consuming especially with the limited computing capability of the on-board computer, posing challenges for practical engineering applications. To conquer these difficulties, this paper makes the following key contributions:(A) a turn-based(sequential decision-making)limited-area impulsive collision avoidance model considering the time delay of precision orbit determination is established for the first time;(B) a novel Selection Probability Learning Adaptive Search-depth Search Tree(SPL-ASST) algorithm is proposed for non-cooperative target avoidance,which improves the decision-making efficiency by introducing an adaptive-search-depth mechanism and a neural network into the traditional Monte Carlo Tree Search(MCTS). Numerical simulations confirm the effectiveness and efficiency of the proposed method.

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An Overview of Bearing Candidates for the Next Generation of Reusable Liquid Rocket Turbopumps

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Chinese Journal of mechanical engineering 2020年第2期33卷 43-55页

作者： Jimin Xu Changhuan Li Xusheng Miao Cuiping Zhang Xiaoyang Yuan Institute of Tribology School of Mechanical EngineeringHefei University of TechnologyHefei 230009China Aerospace Propulsion Institute China Aerospace Science and Technology CorporationXi’an 710100China Science Technology on Combustion Internal Flow and Thermal‑structure LaboratoryNorthwestern Polytechnical UniversityXi’an 710012China Superconducting Materials Research Center Laboratory Northwest Institute for Non-ferrous Metal ResearchXi’an 710016China Key Laboratory of Education Ministry for Modern Design and Rotor‑Bearing System Xi’an Jiaotong UniversityXi’an 710049China

There is a consensus in the aerospace field that the development of reusable liquid rockets can effectively reduce the launch *** pursuit of a long service life and reutilization highly depends on the bearing ***,the rolling element bearings(REBs)used in the existing rocket turbopumps present obvious and increasing limitations due to their mechanical contacting *** REBs,high rotational speed and long service life are two performance indexes that mutually restrict each *** go beyond the DN value(the product of the bearing bore and rotational speed)limit of REBs,the major space powers have conducted substantial explorations on the use of new types of bearings to replace the *** review discusses,first,the crucial role of bearings in rocket turbopumps and the related structural improvements of ***,with the prospect of application to the next generation of reusable liquid rocket turbopumps,the bearing candidates investigated by major space powers are summarized *** promising alternatives to REBs include fluid-film,foil,and magnetic bearings,together with the novel superconducting compound bearings recently proposed by our *** more than ten years of relevant research on fluid-film and magnetic bearings are also *** review is meaningful for the development of long-life and highly reliable bearings to be used in future reusable rocket turbopumps.

关键词： aerospace Reusable liquid rocket turbopumps Rolling element bearings Bearing candidates Review

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research on Self-balancing Control of the High Water-Based Hydraulic Motor’s Swiveling Shaft Friction Pair Based on CFD 3rd

Research on Self-balancing Control of the High Water-Based H...

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3rd International Conference on Mechatronics and Intelligent Robotics, ICMIR 2019

作者： Zhu, Wenjie Zhang, Xinbin Zhao, Jiyun Jiang, Jinlin Dong, Wenyong Shanghai Aerospace Control Technology Institute Shanghai201109 China Shanghai Engineering Research Center of Servo System Shanghai201109 China College of Mechanical and Electrical Engineering CUMT Xuzhou221006 China

ISBN: (纸本)9789811502378

Swiveling shaft friction pair is one of the swiveling cylinder-type high water-based hydraulic motor’s main friction pairs. In the actual condition of high pressure, low speed, and high torque requirements, the swiveling shaft will be affected by the large radial force. Under the action of this force, complete lubricating water film cannot be formed in the swiveling shaft friction pair’s annular gap, which aggravates the wear and tear of swiveling shaft friction pair. In this paper, the load-carrying characteristics of the swiveling shaft friction pair’s lubrication water film are studied by CFD simulation. Based on the theory of hydrostatic bearing, the structure of the swiveling shaft friction pair is optimized, by which the swiveling shaft friction pair can be self-balanced and guarantee the existence of lubrication water film under most working conditions, which can reduce the friction and wear of the swiveling shaft friction pair. © Springer Nature Singapore Pte Ltd. 2020.

关键词： Hydraulic motors

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Dynamics Modeling and Modal Space Control Strategy of Ship-Borne Stewart Platform for Wave Compensation

SSRN

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SSRN 2022年

作者： Chen, Weixing Wen, Yu Tong, Xiaochuan Lin, Chaoxiong Li, Jiang Wang, Shuyou Xie, Wei Mao, Lifeng Zhao, Xianchao Zhang, Weidong Gao, Feng State Key Laboratory of Mechanical System and Vibration School of Mechanical Engineering Shanghai Jiao Tong University Shanghai200240 China Research Center of Marine Intelligent Equipment and Robot Institute of Marine Equipment Shanghai Jiao Tong University Shanghai China Shanghai Marine Equipment Research Institute Shanghai China Department of Automation Shanghai Jiao Tong University Shanghai China

In this paper, based on Kane's method, the dynamic model of a complete ship-borne Stewart platform considering ship motion and actuator inertia is established and modal analysis is carried out. Then, based on the modal theory, the modal space PD controller (MSPDC) and modal space sliding mode controller (MSSMC) are designed to realize the decoupling control of the ship-borne Stewart platform, and its stability is proved by Lyapunov stability analysis. Finally, the simulation physical model of the Stewart platform is established, and the simulation experiments of heave and roll single-DOF sinusoidal wave compensation and multi-DOF random wave compensation are carried out. The results show that the modal space control method has great advantages in attitude compensation accuracy and anti-interference ability. Moreover, The Significant Compensation Rate (SCR) is proposed in this paper to evaluate the six-DOF compensation accuracy under random wave. When compensating for random wave with interference, the position SCR of the proposed modal space sliding mode controller is increased from 95.37 % to 99.28 %, and the angle SCR is increased from 85.57 % to 99.65 % compared with the PD controller with gravity compensation (PDCGC). © 2022, The Authors. All rights reserved.

关键词： Sliding mode control

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Finite-time Consensus Tracking for Multi-motor system Based on Sliding Mode Control 6

Finite-time Consensus Tracking for Multi-motor System Based ...

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6th International Conference on Robotics and automation engineering, ICRAE 2021

作者： Zhang, Tao Yu, Dengxiu Wang, Zhen Jin, Xiaoyue Li, Shengjin Du, Feiping Northwestern Polytechnical University AVIC Qingan Group Co. Ltd School of Mechanical Engineering Xi'an China Northwestern Polytechnical University Unmanned System Research Institution Xi'an China Northwestern Polytechnical University Center for Optical Imagery Analysis and Learning Xi'an China Northwestern Polytechnical University School of Mechanical Engineering Xi'an China Xi'an Aerospace Propulsion Institute Science and Technology on Liquid Rocket Engine Laboratory Xi'an China

ISBN: (纸本)9781665406970

This study investigates a finite-time consensus tracking algorithm for synchronous coordination control of a multimotor system (MMS), which is extremely meaningful to some practical applications with the demand of high-precision performance and stringent convergence time. The graph theory is applied to realize the system modeling of the relationship between the internal parameters of MMS, which can reduce the complexity of the internal parameters of the system and make it more suitable for practical engineering. Then a distributed finite-time consensus controller based on sliding mode control for MMS is proposed, making the time costs in the reaching phase and sliding phase both finite. Simulations are given to illustrate the effectiveness of the proposed approach. © 2021 IEEE.

关键词： Sliding mode control

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Microengineered platforms for characterizing the contractile function of in vitro cardiac models

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Microsystems & Nanoengineering 2022年第1期8卷 29-50页

作者： Wenkun Dou Manpreet Malhi Qili Zhao Li Wang Zongjie Huang Junhui Law Na Liu Craig A.Simmons Jason T.Maynes Yu Sun Department of Mechanical and Industrial Engineering University of TorontoTorontoON M5S 3G8Canada Program in Molecular Medicine The Hospital for Sick ChildrenTorontoON M5G 1X8Canada Department of Biochemistry University of TorontoTorontoON M5S 1A8Canada Institute of Robotics and Automatic Information System and the Tianjin Key Laboratory of Intelligent Robotics Nankai UniversityTianjin 300350China School of Mechanical&Automotive Engineering Qilu University of Technology(Shandong Academy of Sciences)Jinan 250353China School of Mechatronics Engineering and Automation Shanghai UniversityShanghai 200444China Institute of Biomedical Engineering University of TorontoTorontoON M5S 3G9Canada Translational Biology&Engineering Program Ted Rogers Centre for Heart ResearchTorontoON M5G 1M1Canada Department of Anesthesiology and Pain Medicine University of TorontoTorontoON M5S 1A8Canada Department of Anesthesia and Pain Medicine The Hospital for Sick ChildrenTorontoON M5G 1X8Canada Department of Electrical and Computer Engineering University of TorontoTorontoON M5S 3G4Canada Department of Computer Science University of TorontoTorontoON M5T 3A1Canada

Emerging heart-on-a-chip platforms are promising approaches to establish cardiac cell/tissue models in vitro for research on cardiac physiology,disease modeling and drug cardiotoxicity as well as for therapeutic *** still exist in obtaining the complete capability of in situ sensing to fully evaluate the complex functional properties of cardiac cell/tissue *** to contractile strength(contractility)and beating regularity(rhythm)are particularly important to generate accurate,predictive *** new platforms and technologies to assess the contractile functions of in vitro cardiac models is essential to provide information on cell/tissue physiologies,drug-induced inotropic responses,and the mechanisms of cardiac *** this review,we discuss recent advances in biosensing platforms for the measurement of contractile functions of in vitro cardiac models,including single cardiomyocytes,2D monolayers of cardiomyocytes,and 3D cardiac *** characteristics and performance of current platforms are reviewed in terms of sensing principles,measured parameters,performance,cell sources,cell/tissue model configurations,advantages,and *** addition,we highlight applications of these platforms and relevant discoveries in fundamental investigations,drug testing,and disease ***,challenges and future outlooks of heart-on-a-chip platforms for in vitro measurement of cardiac functional properties are discussed.

关键词： cardiac contractile regularity

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Elastic 3D Microelectrodes with Jellyfish-Like Microbumps and Grapping Strips as a Reliable Neural Interface

Elastic 3D Microelectrodes with Jellyfish-Like Microbumps an...

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IEEE International Conference on Micro Electro mechanical systems

作者： Fanqi Sun Qing Liu Xiaoli You Zekai Liang Kai Xue Jun Guo Minghao Wang Jiahao Wang Kai Tao Honglong Chang Bowen Ji Unmanned System Research Institute Northwestern Polytechnical University Xi’an China Ministry of Education Key Laboratory of Micro/Nano Systems for Aerospace School of Mechanical Engineering Northwestern Polytechnical University Xi’an China Collaborative Innovation Center of Northwestern Polytechnical University Shanghai China Department of Engineering Mechanics Applied Mechanics Laboratory Tsinghua University Beijing China Laboratory of Flexible Electronics Technology Tsinghua University Beijing China College of Electronics and Information Hangzhou Dianzi University Hangzhou China

This work reports an elastic 3D microelectrode array with jellyfish-like microbumps and grapping strips for the first time. The soft silicone microbump wrapped by thin-film polyimide (PI) strips is formed by stress-free premolding and post injection molding. The elastic structure serves as a reliable neural interface to push the microelectrode sites closer to the dura mater for high-quality electrocorticogram (ECoG) recording. Besides, the elastic interface with sufficient mechanical strength can withstand the external pressure from overlay of dental cement or cranial window, thanks to its self-compression capability without debonding of grapping strips or electrochemical degradation. Thus, this bionic structure has advantages to reshape the traditional 2D electrodes to 3D for more durable neural recording, and avoid the unbuffered contact of the overlaid sealing cement or window to the underlying soft tissue.

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Hierarchical Optimization of Landing Performance for Lander with Adaptive Landing Gear

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Chinese Journal of mechanical engineering 2019年第2期32卷 24-35页

作者： Zongmao Ding Hongyu Wu Chunjie Wang Jianzhong Ding School of Mechanical Engineering and Automation Beijing University of Aeronautics and Astronautics Beijing System Design Institute of Electro-Mechanic Engineering China Aerospace Science and Industry Corporation Limited Department of Mechanical Engineering Tsinghua University State Key Laboratory of Virtual Reality and Systems Beijing University of Aeronautics and Astronautics

A parameterized dynamics analysis model of legged lander with adaptive landing gear was established. Based on the analysis model, the landing performances under various landing conditions were analyzed by the optimized Latin hypercube experimental design method. In order to improve the landing performances, a hierarchical optimization method was proposed considering the uncertainty of landing conditions. The optimization problem was divided into a higher level(hereafter the "leader") and several lower levels(hereafter the "follower"). The followers took condition?ing factors as design variables to find out the worst landing conditions, while the leader took bu er parameters as design variables to better the landing performance under worst conditions. First of all, sensitivity analysis of landing conditioning factors was carried out according to the results of experimental design. After the sensitive factors were screened out, the response surface models were established to reflect the complicated relationships between sensi?tive conditioning factors, bu er parameters and landing performance indexes. Finally, the response surface model was used for hierarchical optimization iteration to improve the computational e ciency. After selecting the optimum bu er parameters from the solution set, the dynamic model with the optimum parameters was simulated again under the same landing conditions as the simulation before. After optimization, nozzle performance against damage is improved by 5.24%, the acceleration overload is reduced by 5.74%, and the primary strut improves its performance by 21.10%.

关键词： Landing gear Soft landing Sensitivity analysis Response surfaces Hierarchical optimization

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Landing Trajectory Generation using Gauss Pseudo-spectral Method

Landing Trajectory Generation using Gauss Pseudo-spectral Me...

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第40届中国控制会议

作者： Lingxia Mu Jichi Yu Youmin Zhang Lidong Zhang Guo Xie Yuan Zhang Xianghong Xue Department of Automation and Information Engineering Xi'an University of Technology Department of Mechanical Industrial & Aerospace Engineering Concordia University Laboratory of ATM Avionics Technology China Aeronautical Radio Electronics Research Institute

The soft landing of the Mars lander is one of the key problems of Mars exploration. The lander’s dynamic equation is nonlinear and is restricted by various constraints. Analytical solution is hard to be obtained. This paper focuses on planning the Mars landing trajectory by the Gauss pseudo-spectral method. The motion equations during the landing stage is firstly established. The trajectory optimization problem is then established with consideration to dynamic constraints, terminal state constraints, and landing site constraints. The control variables and state variables are discretized using Gauss pseudo-spectral method. Thereby a large-scale sparse nonlinear programming problem is formulated. The problem is then solved by SNOPT solver based on sequential quadratic programming algorithm. Simulation results show the efficiency of the proposed method.

关键词： Mars soft landing Trajectory planning Gauss pseudo-spectral method

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Enhancing Whipple Shield Defense Against Hypervelocity Impacts: Influence of Impactor Geometry and Surface Treatments

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Advances in Space research 2025年

作者： Zhaojun Liu Qiong Wu Hanjun Gao Nianpu Xue Qunzhi Li Hongwei Shi School of Mechanical Engineering & Automation Beihang University Beijing 100191 China Jingdezhen Research Institute of Beihang University Jingdezhen City 333000 PR China Beijing Institute of Spacecraft System Engineering Beijing 100094 China

Spacecraft shields are essential for protecting spacecraft from damage caused by space debris and micrometeoroids. Depending on the source, naturally occurring impactors can reach velocities up to 72 km/s or even higher, particularly for stellar particles, presenting significant challenges for shield impact resistance. In order to enhance the debris protection performance of the Whipple shield, optimize debris cloud distribution, and improve debris kinetic energy dissipation, an SPH model incorporating eight non-spherical impactors and a Whipple shield was established and experimentally validated. This study investigates how the shape and state of the impactor, as well as the shield’s surface condition, affect the impact process using LS-DYNA. Additionally, four reinforcement designs for the Whipple shield were numerically simulated and analyzed. Results indicate that a vertical impact from a dumbbell-shaped projectile causes the most damage to the shield. The tungsten carbide coating significantly improves the kinetic energy dissipation rate of the impactor, reaching 65%, which is 137% higher than that of the traditional Whipple shield. The shot-peened shield expands the fragment cloud distribution area, effectively blocking impact fragments. Statistical analysis of fragment shape and orientation reveals a significant linear correlation between the center of mass height, the shield’s normal projected area, and the kinetic energy dissipation of non-spherical impactors. This model can predict Whipple shield damage from such impactors.

关键词： Atypical space debris Hypervelocity impact SPH simulation Surface strengthening process Whipple shield

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