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Research Square 2021年

作者： Li, Shuangbao Wang, Tingting Chen, Jianen Research Institute of Science and Technology Innovation Civil Aviation University of China Tianjin300300 China College of Science Civil Aviation University of China Tianjin300300 China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China

A new highly efficient elastic-impact bistable nonlinear energy sink (EI-BNES) based on magnetic-elastic impacts with negative stiffness and bistability is proposed and optimized through global dynamical analysis. The EI-BNES has better robustness and higher energy dissipation rates with nearly more than 96.5% for broadband impulsive excitations than the traditional cubic NESs and single bistable NESs. The structure of negative stiffness impacts is realized by reasonable layout of permanent ring magnets and springs. A two-degree-of-freedom (two-DOF) elastic-impact system is established to describe the coupled nonlinear interaction between the main structure and the attached EI-BNES. A global Melnikov reduction analysis (GMRA) is proposed to study global dynamics and homoclinic bifurcations of the reduced two-dimensional subsystem, which is used to explain the mechanism of nonlinear targeted energy transfer (TET) and detect the threshold of impulsive amplitudes of EI-BNES for in-well and compound motions between in-well and cross-well resonance responses. A special type of saddle-center equilibrium points is also found in the non-smooth system of the EI-BNES and can be used to effectively increase the energy dissipation rates. The optimal design criterion of the tuned EI-BNES for better dissipation performance is also first discussed based on the GMRA and numerical techniques for calculating the Melnikov function of the non-smooth systems. The effectiveness of the analytical GMRA is also verified by numerical simulations. © 2021, CC BY.

关键词： Stiffness

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NeRF in Robotics: A Survey

arXiv

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arXiv 2024年

作者： Wang, Guangming Pan, Lei Peng, Songyou Liu, Shaohui Xu, Chenfeng Miao, Yanzi Zhan, Wei Tomizuka, Masayoshi Pollefeys, Marc Wang, Hesheng The University of Cambridge ETH Zurich Switzerland The Department of Automation Shanghai Jiao Tong University Shanghai200240 China The Key Laboratory of System Control and Information Processing Ministry of Education of China China Engineering Research Center of Intelligent Control for Underground Space Ministry of Education School of Information and Control Engineering Advanced Robotics Research Center China University of Mining and Technology Xuzhou221116 China ETH Zurich Zurich Switzerland Mechanical Systems Control Laboratory University of California Berkeley United States

Meticulous 3D environment representations have been a longstanding goal in computer vision and robotics fields. The recent emergence of neural implicit representations has introduced radical innovation to this field as implicit representations enable numerous capabilities. Among these, the Neural Radiance Field (NeRF) has sparked a trend because of the huge representational advantages, such as simplified mathematical models, compact environment storage, and continuous scene representations. Apart from computer vision, NeRF has also shown tremendous potential in the field of robotics. Thus, we create this survey to provide a comprehensive understanding of NeRF in the field of robotics. By exploring the advantages and limitations of NeRF, as well as its current applications and future potential, we hope to shed light on this promising area of research. Our survey is divided into two main sections: The Application of NeRF in Robotics and The Advance of NeRF in Robotics, from the perspective of how NeRF enters the field of robotics. In the first section, we introduce and analyze some works that have been or could be used in the field of robotics from the perception and interaction perspectives. In the second section, we show some works related to improving NeRF's own properties, which are essential for deploying NeRF in the field of robotics. In the discussion section of the review, we summarize the existing challenges and provide some valuable future research directions for reference. © 2024, CC BY-NC-ND.

关键词： Robotics

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TICNet: Three-Branch Real-Time Semantic Segmentation Network with Intensive Compensation of Railway Track Scenes

TICNet: Three-Branch Real-Time Semantic Segmentation Network...

引用

Machine Learning and Computer Application (ICMLCA), International Conference on

作者： Yiwen Bai Lu Yang Lei Zhang Yajing Song School of Transportation Science and Engineering Beihang University Beijing China Tianjin Key Laboratory for Advanced Mechanical System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology) Tianjin China Traffic Control Technology Co. Ltd Beijing China

ISBN: (数字)9798331530334

ISBN: (纸本)9798331530341

With the rapid development of railway traffic system, real-time semantic segmentation plays a crucial role in railway track scene monitoring. However, most of the existing methods use lightweight convolution to reduce the computational complexity, which results in reduced accuracy. To solve this problem, this paper proposes a real-time semantic segmentation network called TICNet, which is specifically used for accurate segmentation of railway track scenes. TICNet uses a novel three-branch structure designed for efficient feature extraction and accurate segmentation. Results on the RailSem19 dataset show that TICNet has a segmentation accuracy of 62.36% mIoU with an inference speed of 81.2 FPS, which is significantly better than many existing methods.

关键词： Accuracy Convolution Semantic segmentation Semantics Focusing Machine learning Feature extraction Real-time systems Computational complexity Monitoring

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Structural Optimization of a Magnetically Operated Actuator Mechanism for 10kV Circuit Breaker

Structural Optimization of a Magnetically Operated Actuator ...

引用

system Simulation Technology and its Application (CCSSTA), IEEE China Conference on

作者： Chao Liang He Tian Guanqiao Zhao Jiangping Li Ziliang Zhu Ruixuan Shen Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology) Tianjin China Tianjin Sanyuan Power Equipment Manufacturing Co. Ltd Tianjin China

ISBN: (数字)9798350366600

ISBN: (纸本)9798350366617

As the demand for reliable power supply in power systems grows, ensuring the performance of circuit breaker operating mechanisms is crucial. This performance is pivotal to the stability of the power grid, the speed of fault recovery, and the equipment’s lifespan. In this paper, we introduce a structural optimization plan for a new magnetic control operating mechanism designed for 10kV circuit breakers. Employing three-dimensional and mathematical modeling, complemented by finite element analysis with Maxwell software, we delved into an in-depth study of the mechanism’s structure, performance, and materials. We further conducted a parametric design and comparative analysis of key components. The simulation results, which exclude the spring load, demonstrate that the optimized circuit breaker can achieve a closing velocity of 3.07 m/s, an electromagnetic force peaking at 2.7 kN, and a closure time minimized to 8.5 ms. These enhancements notably improve the mechanism’s closing efficiency. Consequently, our research introduces a novel perspective to the field of reliability studies for magnetic control operating mechanisms.

关键词： Magnetic cores Circuit breakers Magnetic domains Power system stability Power system reliability Magnetic analysis Magnetosphere Integrated circuit reliability Magnetic circuits Optimization

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Location IoU: A New Evaluation and Loss for Bounding Box Regression in Object Detection

Location IoU: A New Evaluation and Loss for Bounding Box Reg...

引用

International Joint Conference on Neural Networks (IJCNN)

作者： Lu Yang Kai Zhang Jiaqi Liu Chongke Bi Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control Tianjin University of Technology Tianjin China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin China Autobrain (Tianjin) Technology LTD Tianjin China College of Intelligence and Computing Tianjin University Tianjin China

ISBN: (数字)9798350359312

ISBN: (纸本)9798350359329

In the field of object detection bounding box regression, IoU (Intersection over Union) is a commonly used evaluation metric for measuring the overlap between predicted and ground truth bounding boxes. One limitation of IoU, however, is that the gradient goes to zero when there is no intersection between bounding boxes. Recent evaluation metrics have been developed to overcome this problem by incorporating penalty terms and other techniques for improving IoU. Despite these advances, existing methods still suffer to some degree from the problems of small gradients and slow rate of convergence. In this paper, a new evaluation method named LIoU (Location IoU) is proposed to address these issues. It can maximize the shared area of the intersection when used as the loss function and incorporate a variable gradient parameter to fit to datasets of different sizes. The experimental results indicate that we achieve 0.27% and 3.48% accuracy improvements respectively in SSD and YOLOv5 network on the VOC dataset, and 2.23% in the YOLOv5 network on the COCO dataset. The results of this study highlight the effectiveness of LIoU in improving the performance of object detection models.

关键词： YOLO Measurement Location awareness Accuracy Shape Neural networks Benchmark testing

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Elucidating the Rate Limitation of Lithium-Ion Batteries Under Different Charging Conditions Through Polarization Analysis

SSRN

引用

SSRN 2023年

作者： Xie, Wenlong Guo, Peng Gao, Xinlei Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology China Dyson School of Design Engineering Imperial College London London United Kingdom

The charging performance of lithium-ion batteries is significantly affected by the polarization effect, which leads to increased resistance and prolonged charging time. this paper combines experimental testing with numerical simulation to qualitatively and quantitatively investigate the polarization effects under different charging conditions. The results indicate that the proportions of positive and negative polarization to cell polarization are comparable and basically constant with variations in the charging rate. The polarization voltages of different categories within the electrode are positively correlated with the charging rate. At high charging rates, electrochemical polarization accounts for the majority, followed by solid-phase and liquid-phase concentration polarization, while solid-phase and liquid-phase ohmic polarization is relatively negligible. On the other hand, the cell polarization exhibits a non-linear trend with temperature. The lower the temperature, the greater the proportion of negative polarization, while positive polarization is insensitive to temperature. At low temperature charging, the solid-phase concentration polarization of the negative electrode accounts for the majority of electrode polarization, which can be attributed to the larger lithium ion concentration gradient induced by the sluggish diffusion of ions in the active material. In-depth investigation of the polarization effect will provide guidance for achieving more efficient charging under different operating conditions. © 2023, The Authors. All rights reserved.

关键词： Lithium-ion batteries

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Newly Developed Universal Analytical Approach to Incomplete Spherical Conformal Contact Problems: Application to Spherical Plain Bearings with Self-Lubricating Fabric Liner

SSRN

引用

SSRN 2024年

作者： Xue, Yahong Kang, Dongzhuang Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300384 China College of Mechanical Engineering Tianjin University of Technology Tianjin300384 China

To address the conformal contact problem in self-lubricating spherical plain bearings bonded with a self-lubricating layer, a universal analytical model for normal contact between friction-less spheres is established. The accuracy and generality of this new model are verified through numerous finite element analyses. Our model overcomes the limitations of elastic half-space and small deformation assumptions. It can accurately calculate the contact stress distribution of self-lubricating spherical bearings bonded with a self-lubricating layer. Based on the new model, the complex non-linear relationship between the variables is being investigated. The model can be extended and applied to the conformal contact problem of spherical contact surfaces in biomechanics and other fields. © 2024, The Authors. All rights reserved.

关键词： Analytical models

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Bionic Geomagnetic Navigation for Autonomous Underwater Vehicle with Temporal Attention-based Data-Driven Dead Reckoning

TechRxiv

引用

TechRxiv 2023年

作者： Yang, Songnan Zhang, Xiaohui Liu, Ding Bai, Wenqi Liu, Fan The School of Automation and Information Engineering Xi’an University of Technology Shaanxi 710048 China The Institute of Advanced Navigation and Electromagnetics Xi’an University of Technology Shaanxi 710048 China The State Key Laboratory of Eco-Hydraulics in the Northwest Arid Region of China Xi’an University of Technology Shaanxi 710048 China The Shaanxi Key Laboratory of Complex System Control with the Intelligent Information Processing Xi’an University of Technology Shaanxi 710048 China

Numerous studies have demonstrated that numerous animal species are capable of goal-directed navigation using environmental information for dead reckoning. The stable magnetic field of the earth provides important information for the migration of animals over long distances. Inspired by the goal-directed navigation of animals, a novel Geomagnetic Navigation with Temporal Attention-based Data-Driven Dead Reckoning (Attention-DR) method for Autonomous Underwater Vehicles (AUV) is presented in this article, which only utilizes the inclination angle (I) and the declination angle (D) of the Geomagnetic Field (GF) for underwater navigation without any prior knowledge of the geographical location or geographic map. This article proposes a Temporal Attention-based Long Short-Term Memory (TA-LSTM) neural network by combining history, GF information, and location in time series to achieve the optimization heading angle of underwater dead reckoning. Due to its ability to adjust the utilization weights of local and global temporal information in the path, TA-LSTM possesses the capability to continually update neural network model parameters through a data-driven process during the navigation process. This enables the Attention-DR to achieve efficient navigation in regions without prior magnetic maps and overcome navigation failures caused by magnetic field anomalies. The simulation outcomes confirm the efficiency, precision, and practicability of the proposed algorithm. © 2023, CC BY.

关键词： Navigation

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Fast all-optical random number generator

arXiv

引用

arXiv 2022年

作者： Zhao, Jiamin Li, Pu Zhang, Xing Gao, Zhensen Jia, Zhiwei Bogris, Adonis Alan Shore, K. Wang, Yuncai Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education Taiyuan University of Technology Taiyuan030024 China School of Information Engineering Guangdong University of Technology Guangzhou510006 China Guangdong Provincial Key Laboratory of Photonics Information Technology Guangzhou510006 China Key Laboratory of Specialty Fiber Optics and Optical Access Networks Shanghai University Shanghai200444 China Changchun Institute of Optics Fine Mechanics and Physics Chinese Academy of Sciences Changchun130033 China Department of Informatics and Computer Engineering University of West Attica Athens12243 Greece School of Electronic Engineering Bangor University WalesLL57 1UT United Kingdom

We propose a simple and all-optical method for fast random number generation based on the laser mode hopping. Through periodically restarting a two-mode laser operating in the bistable state, a random number stream can be generated due to the spontaneous emission noise. To validate the feasibility of this method, we perform a theoretical simulation using the common vertical-cavity surface-emitting laser (VCSEL) with two polarization modes. Numerical results demonstrate that fast 2.5 Gb/s random number streams can be continuously obtained with verified randomness. This scheme provide a fully monolithic solution for random number generator, due to its simple and all-optical structure. Copyright © 2022, The Authors. All rights reserved.

关键词： Random number generation

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Finite Element Analysis of Series Elastic Actuator for Exoskeleton Robot Joint

Finite Element Analysis of Series Elastic Actuator for Exosk...

引用

IEEE International Conference on Mechatronics and Automation

作者： Pengyu Xi Weimin Ge Sen Zhang Zhili Zhang Teresa Zielinska Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Intelligent Manufacturing College Tianjin Sino-German University of Applied Science Tianjin China Institute of Aeronautics and Applied Mechanics Warsaw University of Technology Warsaw Poland

ISBN: (数字)9781728164168

ISBN: (纸本)9781728164175

The finite element simulation for the joints of an exoskeleton robot is conducted in this paper. Using software OpenSim to simulate the normal walking gait of the human body, the motion angle and moment of the human hip, knee and ankle joints are obtained. Using the obtained data as the input parameters in the finite element simulation of the simulation software Ls-dyna, the strain diagrams and contact force curves of the circular roller and cam disk were obtained. In this study, three commonly used materials are selected: alloy steel, ductile iron and hard aluminum alloy. Finally, the effects of different materials on the key components of the series elastic actuator are studied.

关键词：

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