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Novel Door-opening Method for Six-legged robots Based on Only Force Sensing

Chinese Journal of Mechanical Engineering 2017年第5期30卷 1227-1238页

作者： Zhi-Jun Chen Feng Gao Yang Pan State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai GQY Robot Limited Company

Current door-opening methods are mainly developed on tracked, wheeled and biped robots by applying multi-DOF manipulators and vision systems. However, door-opening methods for six-legged robots are seldom studied, especially using 0-DOF tools to operate and only force sensing to detect. A novel door-opening method for six-legged robots is developed and imple- mented to the six-parallel-legged robot. The kinematic model of the six-parallel-legged robot is established and the model of measuring the positional relationship between the robot and the door is proposed. The measurement model is completely based on only force sensing. The real- time trajectory planning method and the control strategy are designed. The trajectory planning method allows the maximum angle between the sagittal axis of the robot body and the normal line of the door plane to be 45°. A 0-DOF tool mounted to the robot body is applied to operate. By integrating with the body, the tool has 6 DOFs and enough workspace to operate. The loose grasp achieved by the tool helps release the inner force in the tool. Experiments are carried out to validate the method. The results show that the method is effective and robust in opening doors wider than 1 m. This paper proposes a novel door-opening method for six-legged robots, which notably uses a O-DOF tool and only force sensing to detect and open the door.

关键词： Door-opening·Six-legged robots· Forcesensing · O-DOF tool

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Continual Reinforcement Learning for Digital Twin Synchronization Optimization

arXiv

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arXiv 2025年

作者： Tong, Haonan Chen, Mingzhe Zhao, Jun Hu, Ye Yang, Zhaohui Liu, Yuchen Yin, Changchuan The Beijing Key Laboratory of Network System Architecture and Convergence The Beijing Advanced Information Network Laboratory Beijing University of Posts and Telecommunications Beijing China Singapore The Department of Electrical and Computer Engineering Frost Institute for Data Science and Computing University of Miami Coral GablesFL33146 United States The Department of Industrial and Systems Engineering University of Miami Coral GablesFL33146 United States The College of Information Science and Electronic Engineering Zhejiang University Zhejiang Hangzhou310027 China The Department of Computer Science North Carolina State University RaleighNC27695 United States The Beijing Key Laboratory of Network System Architecture and Convergence China The Beijing Advanced Information Network Laboratory Beijing University of Posts and Telecommunications Beijing100876 China

This article investigates the adaptive resource allocation scheme for digital twin (DT) synchronization optimization over dynamic wireless networks. In our considered model, a base station (BS) continuously collects factory physical object state data from wireless devices to build a real-time virtual DT system for factory event analysis. Due to continuous data transmission, maintaining DT synchronization must use extensive wireless resources. To address this issue, a subset of devices is selected to transmit their sensing data, and resource block (RB) allocation is optimized. This problem is formulated as a constrained Markov process (CMDP) problem that minimizes the long-term mismatch between the physical and virtual systems. To solve this CMDP, we first transform the problem into a dual problem that refines RB constraint impacts on device scheduling strategies. We then propose a continual reinforcement learning (CRL) algorithm to solve the dual problem. The CRL algorithm learns a stable policy across historical experiences for quick adaptation to dynamics in physical states and network capacity. Simulation results show that the CRL can adapt quickly to network capacity changes and reduce normalized root mean square error (NRMSE) between physical and virtual states by up to 55.2%, using the same RB number as traditional methods. © 2025, CC BY-NC-SA.

关键词： Markov processes

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Enhanced heating effect of lakes under global warming

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Nature Communications 2025年第1期16卷 1-11页

作者： Qiu, Yuanlin Chen, Jie Chen, Deliang Thiery, Wim Mercado-Bettín, Daniel Xiong, Lihua Xia, Jun Woolway, R. Iestyn Wuhan University State Key Laboratory of Water Resources Engineering and Management Wuhan China Wuhan University Hubei Key Laboratory of Water System Science for Sponge City Construction Wuhan China Tsinghua University Department of Earth System Science Beijing China Vrije Universiteit Brussel Department of Water and Climate Brussels Belgium Spanish National Research Council Centre for Advanced Studies of Blanes Blanes Spain Bangor University School of Ocean Sciences Wales United Kingdom

Lakes play a crucial role in shaping both local and regional climates through heat exchange with the atmosphere. Amid global climate change, these interactions have undergone significant shifts. However, our understanding of the global heat release from lakes to the atmosphere, and its future trajectory, remains limited. In this study, we investigate changes in global lake heat release patterns and identify an amplified increase in heat release, particularly in mid to high latitudes (>45°N). This amplification is linked with a feedback mechanism, where the reduction in lake ice cover not only reduces the insulating effect between the warmer lake water and the colder atmosphere but also leads to increased heat absorption by lakes. As a result, lakes in mid-high latitudes experience a greater relative increase in heat release, primarily through upward thermal radiation, compared to lakes at lower latitudes with comparable surface water temperature increases. Additionally, seasonal variations in latent heat flux intensify the heat release during warmer seasons compared to colder ones. Future projections suggest substantially greater heat release compared to historical trends. © The Author(s) 2025.

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Deep Learning Based Vehicular Millimeter-Wave Channel Prediction Using Visual Information

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IEEE Antennas and Wireless Propagation Letters 2025年

作者： Wang, Shirui He, Ruisi Yang, Mi Ai, Bo Zhang, Xuejian Zhong, Zhangdui Zhang, Haoxiang Han, Jiahui Liu, Bingcheng Beijing Jiaotong University State Key Laboratory of Advanced Rail Autonomous Operation the School of Electronics and Information Engineering the Frontiers Science Center for Smart High-speed Railway System Beijing100044 China Ministry of Industry and Information Technology China Academy of Industrial Internet Beijing100044 China Chinese Academy of Sciences Aerospace Information Research Institute Beijing100094 China

Millimeter-wave channel prediction requires detailed and accurate environmental information due to challenges of non-line-of-sight transmission and severe reflection and scattering. Image information conveniently reflects real-time changes of physical environment and provides a promising solution for millimeter-wave channel modeling. However, research on millimeter-wave channel prediction based on RGB images is still in its exploratory stage. Meanwhile, RGB images introduce new influencing factors, such as visual angle changes, leading to inaccurate prediction. This article proposes a millimeter-wave channel prediction model based on propagation knowledge and visual information, which enhances original RGB image features while combining manual features from specific domain prior knowledge in propagation. Experimental results show that the proposed model outperforms traditional RGB image-based prediction for a multi-scenario, multiview fused dataset, achieving a symmetric mean absolute percentage error as low as 4.16%. In addition, the proposed model demonstrates enhanced stability and interpretability. © 2002-2011 IEEE.

关键词： Prediction models

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Analysis and Optimization of a Spatial Parallel Mechanism for a New 5-DOF Hybrid Serial-Parallel Manipulator

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Chinese Journal of Mechanical Engineering 2018年第3期31卷 60-68页

作者： Dong-Sheng Zhang Yun-Dou Xu Jian-Tao Yao Yong-Sheng Zhao Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of National Education Yanshan University

Hybrid manipulators have potentially application in machining industries and attract extensive attention from many researchers on the basis of high sti ness and high dexterity. Therefore,in order to expand the application prospects of hybrid manipulator,a novel 5?degree?of?freedom(DOF) hybrid serial?parallel manipulator(HSPM) is proposed. Firstly,the design plan of this manipulator is introduced. Secondly,the analysis of this manipulator is carried out in detail,including kinematics analysis,statics analysis,and workspace analysis. Especially,an amplitude equivalent method of disposing the over?constrained force/couple to the non?overconstrained force/couple is used in the statics analysis. Then,three performance indices are used to optimize the PM. Two of them have been widely used,and the third one is a new index which considers the characteristics of the actuated force. Based on the performance indices,the performance atlas is drawn and the optimal design of the PM is investigated. In order to satisfy the anticipant kinetic characteristics of the PM,the verification of the optimized physical dimension is done and the workspace based on the optimized physical dimension is carried out. This paper will lay good theoretical foundations for application of this novel HSPM and also can be applied to other hybrid manipulators.

关键词： Parallel mechanism Performance indices Optimal design Performance atlas

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Vibration Transfer Function of Railway Vehicle system and its Spatial Coherence Under Vertical Track Irregularity Conditions

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Chinese Journal of Mechanical Engineering 2025年第2期 380-399页

作者： Peng Lu Xi Wang Yu Hou State Key Laboratory of Advanced Rail Autonomous Operation Beijing Jiaotong University Frontiers Science Center for Smart High-speed Railway System Beijing Jiaotong University School of Mechanical Electronic and Control EngineeringBeijing Jiaotong University

Current research on rail vehicle system vibrations primarily relies on numerical methods, with vibration transfer functions commonly derived through data fitting. However, the physical mechanisms underlying these vibrations are not well understood. To clarify the vibration transfer function and its characteristics, four basic input vectors are defined, and an analytical method is proposed. The vibration transfer functions of the vehicle system are solved, and their spatial coherence is analyzed. The results show that there are two spatial scales and four coherent modes in the vehicle system. The track irregularity wavelengths are combined with two spatial scales to alter the proportions of basic input vectors and then show the characteristics of spatial coherence. Four coherent modes are involved in wheel-rail force and primary suspension force; two coherent modes are involved in bogie vertical motion; and their dominant modes vary with the input frequency. On the other hand, the coherent modes involved in the bogie pitching motion and vehicle body motion are single and fixed over the whole range of frequency. This study presents an analytical method for the rapid solution of dynamic responses in vehicle systems and systematically analyzes the coherence behavior of vibration transfer functions with respect to tracking irregularity wavelengths.

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Joint Angle-Delay Sparse Structured Compressed Sensing for ISAC Channel Estimation

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IEEE Transactions on Vehicular Technology 2025年

作者： He, Zeqian He, Ruisi Ai, Bo Zhang, Haoxiang Zhong, Zhangdui Beijing Jiaotong University State Key Laboratory of Advanced Rail Autonomous Operation Beijing100044 China Beijing Jiaotong University School of Electronics and Information Engineering Beijing100044 China Beijing Jiaotong University Frontiers Science Center for Smart High-speed Railway System Beijing100044 China Ministry of Industry and Information Technology China Academy of Industrial Internet Beijing100102 China

In the upcoming 6 G communications, radar sensing will be integrated with communication to support a wide range of application scenarios. However, in complex Integrated Sensing and Communication (ISAC) channels, radar targets and communication scatterers may overlap, leading to similar sparse distributions of the sensing and communication channels in both the angle and delay domains. Additionally, the increasing use of compressed sensing (CS) for estimating communication parameters has given rise to numerous CS algorithms based on the expectation maximization (EM) method. However, due to the unique characteristics of the channel in specific scenarios, designing the channel sparse structure has become a crucial aspect of EM-base algorithm. Therefore, there is an urgent need to develop an appropriate channel sparse structure and design a CS algorithm specifically for the ISAC scenario. In this paper, we address the problem of channel estimation in a time-division duplex multi-input multi-output ISAC system using a bi-static model. We introduce a Joint Angle-Delay Sparse Structure (JADSS) to capture the sparsity characteristics of the ISAC channel in both the angle and delay domains. Furthermore, we design a message passing estimator within the framework of an EM-based double-loop algorithm to estimate the ISAC channel. Through simulations, we demonstrate that the proposed CS algorithm utilizing JADSS achieves competitive error performance. © 1967-2012 IEEE.

关键词： Channel estimation

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Ultra-thin Glass Film Coated with Graphene: A New Material for Spontaneous Emission Enhancement of Quantum Emitter

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Nano-Micro Letters 2015年第3期7卷 261-267页

作者： Lu Sun Chun Jiang State Key Laboratory of Advanced Optical Communication System and Networks Shanghai Jiao Tong University

We propose an ultra-thin glass film coated with graphene as a new kind of surrounding material which can greatly enhance spontaneous emission rate(SER) of dipole emitter embedded in it. With properly designed parameters,numerical results show that SER-enhanced factors as high as 1.286 9 106 can be achieved. The influences of glass film thickness and chemical potential/doping level of graphene on spontaneous emission enhancement are also studied in this paper. A comparison is made between graphene and other coating materials such as gold and silver to see their performances in SER enhancement.

关键词： Graphene surface plasmons Graphene plasmonics Quantum electrodynamics Superradiance Subwavelength structures

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Oscillating Body Design for A 3-DOF Wave Energy Converter

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China Ocean Engineering 2018年第4期32卷 453-460页

作者： CHEN Wei-xing GAO Feng MENG Xiang-dun State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Chejing Robot Technology Co. Ltd.

Ocean wave energy converters(WECs) are obtaining more and more attentions in the world. So far, many types of converters have been invented. Oscillating body systems are a major class of WECs, which typically have one degree of freedom(DOF), and the power absorption efficiency is not quite satisfactory. In this paper, a 3-DOF WEC is proposed and a simplified frequency-domain dynamic model of the WEC depending on the linear potential theory is conducted. The performances of three geometries of the oscillating body including the cone, the cylinder and the hemisphere have been compared, and the results show that the hemisphere is more suitable for the 3-DOF ***, the relationship among the parameters of the hemisphere is established based on the equal natural frequencies of the heave and pitch(or roll) motions, and the results show that lowering the center of gravity leads to the better power absorption in the pitch(or roll) motion. In the end, the power matrixes of different sizes of the hemispheres under different irregular waves are obtained, which can give a size design reference for engineers.

关键词： WEC 3-DOF geometry dynamic parameters size design reference

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Fractional-order visco-plastic constitutive model for uniaxial ratcheting behaviors

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Applied Mathematics and Mechanics(English Edition) 2019年第1期40卷 49-62页

作者： Wenjie ZHAO Shaopu YANG Guilin WEN Xuehong REN State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University State Key Laboratory of Mechanical Behavior in Traffic Engineering Structure and System Safety Shijiazhuang Tiedao University

This paper proposes a novel unified visco-plastic constitutive model for uniaxial ratcheting behaviors. The cyclic deformation of the material presents remarkable time-dependence and history memory phenomena. The fractional(fractional-order)derivative is an efficient tool for modeling these phenomena. Therefore, we develop a cyclic fractional-order unified visco-plastic(FVP) constitutive model. Specifically, within the framework of the cyclic elasto-plastic theory, the fractional derivative is used to describe the accumulated plastic strain rate and nonlinear kinematic hardening rule based on the Ohno-Abdel-Karim model. Moreover, a new radial return method for the back stress is developed to describe the unclosed hysteresis loops of the stress-strain *** capacity of the FVP model used to predict the cyclic deformation of the SS304 stainless steel is verified through a comparison with the corresponding experimental data found in the literature(KANG, G. Z., KAN, Q. H., ZHANG, J., and SUN, Y. F. Timedependent ratcheting experiments of SS304 stainless steel. International Journal of Plasticity, 22(5), 858–894(2006)). The FVP model is shown to be successful in predicting the rate-dependent ratcheting behaviors of the SS304 stainless steel.

关键词： cyclic visco-plastic constitutive fractional derivative fractional-order uni-fied visco-plastic(FVP)model rate-dependent ratcheting

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