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作者： Yixiao Zheng Bixi Yan Chao Ma Xinyu Wang Haoyang Xue School of Instrument Science and Optoelectronic Engineering Beijing Information Science and Technology University Beijing Key Laboratory of Intelligent Space Robotic Systems Technology and Applications Beijing Institute of Spacecraft System Engineering

Both obstacle and path planning are of significance for autonomous visual navigation of a mobile robot which is able to realize free movement and obstacle *** this paper,a scheme of obstacle detection which is based on binocular vision to identify obstacles is constructed and it is combined with improved A* algorithm for obstacle avoidance motion for mobile robot ***,a binocular vision system to detect the robot's perception of the environment is used and the visual information is *** a Gaussian filter is used to reduce the noise in the image,and the grayscale image is obtained through the binocular vision *** gray scale map is matched with SAD(Sum of Absolute Differences) in order to obtain the disparity image with ***,the location information of the obstacle is extracted through the environmental depth information contained in the disparity image,and the improved A* algorithm is used as the path planning algorithm in this paper,which can modify the path of the planning ***,the detection experiment of the robot visual obstacle avoidance system was established and the optimal path was *** examples show that,the obstacle avoidance system can complete the task of obstacle detection and give a better path for the mobile robot.

关键词： image filter Research on obstacle detection and path planning based on visual navigation for mobile robot

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Locomotion Stability Analysis of Lower Extremity Augmentation Device

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Journal of Bionic Engineering 2019年第1期16卷 99-114页

作者： Likun Wang Chaofeng Chen Wei Dong Zhijiang Du Yi Shen Guangyu Zhao State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China School of Astronautics Harbin Institute of TechnologyHarbin 150001China Weapon Equipment Research Institute China Ordnance Industries GroupBeijing 102202China

Stability is of great significance in the theoretical framework of biped ***-time control and walking patterns planning are on the premise that the robot works in the stable *** this paper,we address the crucial issue of the locomotion stability based on the modified Poincare return map and the hybrid *** akin to the traditional stability criteria,i.e.,the Zero Moment Point(ZMP)and the Center of Mass(CoM),the modified Poincare return map is more appropriate for both dynamic walking arid non-periodic ***,a novel high-level reinforcement learning methodology,so-called active PI2 CMA-ES,is proposed in this paper to plan the exoskeleton *** proposed learning methodology demonstrates that the locomotion of the exoskeleton is asymptotically stable according to the modified Poincare return map ***,the proposed learning methodology is tested by the Lower Extremity Augmentation Device(LEAD)and its effectiveness is verified by the experiments.

关键词： biped locomotion dynamic walking Dynamic Movement Primitives (DMP),stability exoskeleton bioinspiration

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Effects of Microstructure and Temperature on Short Fatigue Crack Propagation Behaviour of Powder Metallurgy Superalloy Fgh4098 in Vacuum

SSRN

引用

SSRN 2022年

作者： Zhang, L.C. Jiang, Rong Wang, Y.C. Zhang, L. Liu, J.T. Zhang, Y.W. Song, Y.D. Key Laboratory of Aero-engine Thermal Environment and Structure Ministry of Industry and Information Technology College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics Nanjing210016 China Jiangsu Province Key Laboratory of Aerospace Power System College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics Nanjing210016 China High Temperature Material Institute Central Iron and Steel Research Institute Beijing100081 China State Key Laboratory of Mechanics and Control Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing210016 China

Short fatigue crack propagation (SFCP) behaviour of a powder metallurgy (PM) superalloy (i.e. FGH4098) for aeroengine turbine disc application was investigated at room temperature and 650°C in vacuum (10-3 pa) by in-situ fatigue test. The SFCP mechanism was analyzed by the microstructural characterization and assessment of the SFCP rate. The results show that the SFCP resistance of fine grained (FG) FGH4098 is slightly better than that of course grained (CG) FGH4098 at room temperature due to the hindering effects of grain boundary, and close to that of CG FGH4098 at 650°C. The temperature exerts more evident influence on SFCP behaviour of FG FGH4098 due to the grain boundary oxidation compared with that of CG FGH4098. In the scenario which grain boundary oxidation is absent or insignificant, SFCP shows transgranular feature and is closely related to slip bands linked to the slip systems with high Schmid factor and/or geometric compatibility factor. Grain boundary oxidation still occurs in both FG and CG FGH4098 alloy and mainly forms Cr oxides at 650°C, which results in intergranular or mixed-inter-transgranular SFCP and promotes SFCP to some extent for FG FGH4098 alloy. © 2022, The Authors. All rights reserved.

关键词： Fatigue crack propagation

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An Application of Variable Switching Frequency PWM on SiC-Based Paralleled Inverters for Motor Drive

An Application of Variable Switching Frequency PWM on SiC-Ba...

引用

International Conference on Power Electronics and Motion Control (IPEMC)

作者： Xuan Zhao Dong Jiang Qiao Li Yingtao Ma Yang Liu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China State Key Laboratory for Traction and Control System of EMU and Locomotive Beijing China

ISBN: (数字)9781728153018

ISBN: (纸本)9781728153025

SiC power devices applied in motor drives have brought the advantages of higher efficiency and power density, but with the problem of more serious electromagnetic interference (EMI). Using advanced topologies can help to mitigate EMI, including the paralleled inverters. In this paper, the variable switching frequency PWM (VSFPWM) for paralleled inverters based on predicted circulating current is used to make better use of the coupled inductor's saturation limit, which is determined by the high frequency circulating current peak. Under the high-frequency operating conditions of the SiC inverter, the VSFPWM strategy will allow the switching frequency to change in a wide range, and the switching losses and EMI will be well improved relative to the constant switching frequency PWM (CSFPWM), while the circulating current peak is controlled within the limit. Moreover, the higher normal frequency (f s N), the larger EMI attenuation after VSF operation. Experimental results are provided to verify the proposed method.

关键词： Motor drives Silicon carbide Switching frequency Electromagnetic interference Switching loss Pulse width modulation Inverters

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Error-free approximation of explicit linear MPC through lattice piecewise affine expression

arXiv

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arXiv 2021年

作者： Xu, Jun Lou, Yunjiang De Schutter, Bart Xiong, Zhenhua School of Mechanical Engineering and Automation Harbin Institute of Technology Shenzhen China Key Laboratory of System Control and Information Processing Ministry of Education Shanghai China Delft Center for Systems and Control Delft University of Technology Netherlands State Key Laboratory of Mechanical Systems and Vibration Shanghai Jiao Tong University Shanghai China

In this paper, the disjunctive and conjunctive lattice piecewise affine (PWA) approximations of explicit linear model predictive control (MPC) are proposed. The training data are generated uniformly in the domain of interest, consisting of the state samples and corresponding affine control laws, based on which the lattice PWA approximations are constructed. Re-sampling of data is also proposed to guarantee that the lattice PWA approximations are identical to the explicit MPC control law in the unique order (UO) regions containing the sample points as interior points. Additionally, if all the distinct affine functions have been sampled, the disjunctive lattice PWA approximation constitutes a lower bound while the conjunctive lattice PWA approximation formulates an upper bound of the original optimal control law. The equivalence of the two lattice PWA approximations then guarantees that the approximations are error-free in the domain of interest, which is tested through a statistical guarantee. The complexity of the entire procedure is analyzed, which is polynomial with respect to the number of samples. The performance of the proposed approximation strategy is tested through two simulation examples, and the results show that with a moderate number of sample points, we can construct lattice PWA approximations that are equivalent to the optimal control law of the explicit linear MPC. © 2021, CC0.

关键词： Model predictive control

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An improved calculation method for static capacitance in inductor windings

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Progress In Electromagnetics Research C 2020年 104卷 25-36页

作者： Du, Mingxing Zhang, Yuxiao Wang, Hongbin Tian, Ye Ouyang, Ziwei Wei, Kexin Tianjin Key Laboratory of Control Theory & Applications in Complicated System Tianjin University of Technology Tianjin China State Key Laboratory of Reliability and Intelligence of Electrical Equipment Hebei University of Technology Tianjin China

This paper proposes an improved method for calculating static capacitance between two conductors with circular cross-sections in inductor windings. It considers the effects of electric field coupling and energy distribution on static capacitance. In this paper, the capacitance between two conductors in inductor windings is calculated by the improved calculation method and finite-element method (FEM), respectively. The relative error of the improved calculation method is between 0.11% and 4.51% compared to the FEM. In order to verify the effectiveness of this method for inductor winding, the orthogonal stacking winding and staggered stacking winding are chosen as calculation examples to accurately predict the static capacitance of multi-layer circular-section induction coils. Finite element models for the two types of windings are built to determine the capacitances for our 3 × 3 array arrangement winding. The results show that the improved calculation method proposed in this paper highly conforms to FEM. Finally, we adopt an air-cored cylindrical inductor winding for experimental verification, and the improved calculation method is proved to be correct. © 2020, Electromagnetics Academy. All rights reserved.

关键词： Capacitance

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Robust Multi-agent Communication Based on Decentralization-Oriented Adversarial Training

arXiv

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arXiv 2025年

作者： Ma, Xuyan Wang, Yawen Wang, Junjie Xie, Xiaofei Wu, Boyu Li, Shoubin Xu, Fanjiang Wang, Qing State Key Laboratory of Intelligent Game Beijing China Science and Technology on Integrated Information System Laboratory Institute of Software Chinese Academy of Sciences Beijing China University of Chinese Academy of Sciences Beijing China Singapore Management University Singapore

In typical multi-agent reinforcement learning (MARL) problems, communication is important for agents to share information and make the right decisions. However, due to the complexity of training multi-agent communication, existing methods often fall into the dilemma of local optimization, which leads to the concentration of communication in a limited number of channels and presents an unbalanced structure. Such unbalanced communication policy are vulnerable to abnormal conditions, where the damage of critical communication channels can trigger the crash of the entire system. Inspired by decentralization theory in sociology, we propose DMAC, which enhances the robustness of multiagent communication policies by retraining them into decentralized patterns. Specifically, we train an adversary DMAC Adv which can dynamically identify and mask the critical communication channels, and then apply the adversarial samples generated by DMAC Adv to the adversarial learning of the communication policy to force the policy in exploring other potential communication schemes and transition to a decentralized structure. As a training method to improve robustness, DMAC can be fused with any learnable communication policy algorithm. The experimental results in two communication policies and four multi-agent tasks demonstrate that DMAC achieves higher improvement on robustness and performance of communication policy compared with two state-of-the-art and commonly-used baselines. Also, the results demonstrate that DMAC can achieve decentralized communication structure with acceptable communication cost. Copyright © 2025, The Authors. All rights reserved.

关键词： Adversarial machine learning

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Model-Based and Data-Driven Control of Event- and Self-Triggered Discrete-Time LTI systems

arXiv

引用

arXiv 2022年

作者： Wang, Xin Berberich, Julian Sun, Jian Wang, Gang Allgöwer, Frank Chen, Jie The Key Laboratory of Intelligent Control and Decision of Complex System Beijing Institute of Technology Beijing10081 China The Beijing Institute of Technology Chongqing Innovation Center Chongqing401120 China The University of Stuttgart Institute for Systems Theory and Automatic Control Stuttgart70550 Germany The Department of Control Science and Engineering Tongji University Shanghai201804 China The State Key Lab of Intelligent Control and Decision of Complex Systems School of Automation Beijing Institute of Technology Beijing100081 China

The present paper considers the model-based and data-driven control of unknown linear time-invariant discretetime systems under event-triggering and self-triggering transmission schemes. To this end, we begin by presenting a dynamic event-triggering scheme (ETS) based on periodic sampling, and a discrete-time looped-functional approach, through which a model-based stability condition is derived. Combining the model-based condition with a recent data-based system representation, a data-driven stability criterion in the form of linear matrix inequalities (LMIs) is established, which also offers a way of co-designing the ETS matrix and the controller. To further alleviate the sampling burden of ETS due to its continuous/periodic detection, a self-triggering scheme (STS) is developed. Leveraging pre-collected input-state data, an algorithm for predicting the next transmission instant is given, while achieving system stability. Finally, numerical simulations showcase the efficacy of ETS and STS in reducing data transmissions as well as of the proposed co-design methods. Copyright © 2022, The Authors. All rights reserved.

关键词： Linear matrix inequalities

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Multiple-Photon Resonance Enabled Quantum Interference in Emission Spectroscopy of N_(2)^(+)

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Ultrafast Science 2024年第2期4卷 1-7页

作者： Xiang Zhang Qi Lu YaLei Zhu Jing Zhao Rostyslav Danylo Liang Xu Mingwei Lei Hongbing Jiang Chengyin Wu Zhedong Zhang Aurélien Houard Vladimir Tikhonchuk AndréMysyrowicz Qihuang Gong Songlin Zhuang Zengxiu Zhao Yi Liu Shanghai Key Lab of Modern Optical System University of Shanghai for Science and Technology.516Jungong Road200093 ShanghaiChina Department of Physics National University of Defense TechnologyChangsha 410073China Laboratoire d'Optique Appliquee ENSTA ParisEcole Polytechnique CNRSInstitut Polytechnique de Paris828 Boulevard des Marechaux91762 Palaiseau CedexFrance State Key Laboratory for Mesoscopic Physics School of PhysicsPeking UniversityBejing 100871China Department of Physics City University of Hong KongKowloonHong Kong SAR Centre Lasers Intenses et Applications University of Bordeaux-CNRS-CEA351 Cours de la Liberation33405 Talence Cedex France Extreme Light Infrastructure ERIC ELI Beamlines Facility25241 Doln BrezanyCzech Republic CAS Center for Excellence in Ultra-intense Laser Science Shanghai 201800China

Quantum interference occurs frequently in the interaction of laser radiation with materials,leading to a series of fascinating effects such as lasing without inversion,electromagnetically induced transparency,Fano resonance,*** quantum interference effects are mostly enabled by single-photon resonance with transitions in the matter,regardless of how many optical frequencies are ***,we report on quantum interference driven by multiple photons in the emission spectroscopy of nitrogen ions that are resonantly pumped by ultrafast infrared laser *** the spectral domain,Fano resonance is observed in the emission spectrum,where a laser-assisted dynamic Stark effect creates the *** the time domain,the fast-evolving emission is measured,revealing the nature of free-induction decay arising from quantum radiation and molecular *** findings clarify the mechanism of coherent emission of nitrogen ions pumped with mid-infrared pump laser and are found to be *** present work opens a route to explore the important role of quantum interference during the interaction of intense laser pulses with materials near multiple photon resonance.

关键词： pumped pump Quantum

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Trajectory Planning Simulation of 3-DoF Parallel Wrist Mechanisms Based on SimMechanics 9

Trajectory Planning Simulation of 3-DoF Parallel Wrist Mecha...

引用

9th IEEE International Conference on Cyber technology in Automation, Control and Intelligent systems, CYBER 2019

作者： Yang, Chen Xin, Liu Shimin, Wei Ying, Zhang Qineng, Huang School of Automation Beijing University of Posts and Telecommunications Beijing100876 China Beijing Institute of Spacecraft System Engineering Beijing Key Laboratory of Intelligent Space Robotic System Technology and Applications Beijing100094 China

ISBN: (纸本)9781728107691

In this paper, the trajectory planning problem of a 3-DoF parallel wrist mechanism based on SimMechanics is proposed, which is a symmetric spherical 3-RRR parallel mechanism. The formulation of the inverse kinematics for the mechanism is firstly established by D-H matrix method, and the analytical solution is obtained. Then, the trajectory planning analysis of the mechanism is performed. Finally, the mechanism model is constructed based on the SimMechanics module of Matlab/Simulink, and the trajectory planning simulation of the mechanism is carried out. The simulation results agree well with the theoretical results, which indicate that the proposed method is feasible and convenient for the trajectory simulation of parallel mechanisms. © 2019 IEEE.

关键词： Inverse kinematics

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