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Thermal analysis of lubricated three-dimensional contact bodies considering interface roughness

Frontiers of Mechanical Engineering 2022年第2期17卷 177-191页

作者： Jiqiang WU Liqin WANG Zhen LI Peng LIU Chuanwei ZHANG MIIT Key Laboratory of Aerospace Bearing Technology and Equipment Harbin Institute of TechnologyHarbin 150001China State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150080China

Surface roughness and thermal action are of remarkable importance in the lubrication performance of mechanical components,especially in extreme ***,available studies mainly focus on the full-film lubrication conditions without considering temperature rise and real 3D surface roughness due to the complexity of surface topography and temperature ***,studies on the interfacial thermal behaviors of 3D rough surface lubricated contact in an extended range of working conditions remain *** this paper,a deterministic mixed thermal elastohydrodynamic lubrication model considering real 3D surface roughness and thermal effects is *** this model,pressure and temperature are coupled with each other,the computation of elastic deformation is accelerated through the discrete convolution and fast Fourier transform method,the temperature field is calculated with the column sweeping technique,and the semi-system method is introduced to improve convergence and numerical stability under severe *** model is validated by comparing its results with available published numerical and experimental *** thermal behaviors of the contact interface are studied in a wide range of working *** influences of surface roughness and thermal effect on lubrication performance are *** results show that the proposed model can be used as a powerful analysis tool for lubrication performance and temperature prediction in various heavy-load,high-speed lubricated components over a wide range of lubrication conditions.

关键词： thermal elastohydrodynamic lubrication surface roughness effect thermal effect temperature characteristics severe conditions

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An Effective Rotor-Shape Optimization Method for IPM Motor with 1/2 Slot per Phase per Pole

An Effective Rotor-Shape Optimization Method for IPM Motor w...

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2023 IEEE International Conference on Applied Superconductivity and Electromagnetic Devices, ASEMD 2023

作者： Yu, Guodong Sun, Shuqi Li, Junlong Xiao, Lijun Xu, Yongxiang Zou, Jibin Harbin Institute of Technology State Key Laboratory of Robotics and System Harbin China

ISBN: (纸本)9798350301571

Although IPM motor with 1/2 slot per phase per pole has a relatively less rotor loss in comparison with other fractional slot concentrated winding (FSCW), the problems of THD of back-EMF and cogging torque are worse, which limits its application in electric vehicles and other industry fields. This paper proposes an effective rotor-shape optimization method to suppress both THD of back-EMF and cogging torque for improving torque ripple problem. Different from the prevalent rotor optimization methods, the proposed rotor-shape optimization method associates both shape function optimization of rotor surface with PM shaping, which can effectively decrease optimization parameters, and enhance optimization efficiency. To clarify the optimization strategy, the back-EMF and cogging torque for this PM motor with 1/2 slot per phase per pole are analyzed firstly. Then, the proposed optimization method is presented in detail. Finally, the optimized IPM motor is prototyped and its experimental results verifies the effectiveness of the proposed optimization method. © 2023 IEEE.

关键词： back-EMF cogging torque IPM motor optimization method

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Data Augmentation for Improving CNNs in Medical Image Classification 8

Data Augmentation for Improving CNNs in Medical Image Classi...

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8th International Conference on Intelligent Computing and Signal Processing, ICSP 2023

作者： Ren, Yi He, Zengmin Deng, Yang Huang, Bo Harbin Institute of Technology State Key Laboratory of Robotics and System Harbin China

ISBN: (纸本)9798350302455

Medical image is essential for physicians to diagnose diseases. And convolutional neural networks (CNNs) have gained momentum for computer-aided diagnosis (CAD) medical image. However, there are still challenges in CNNs related to a lack of data and class-imbalanced datasets. Data augmentation is utilized to address the issues mentioned above. In this study, the Pseudo-color enhancement algorithm (OCEAN and TWILIGHT), common linear transform, CLAHE enhancement, and K-means clustering algorithm were applied to pneumonia X-ray images for data augmentation. Thus, five processed datasets were finally obtained. The results indicated that five data-augmentation methods effectively improved the performance of CNNs for the pneumonia X-ray images binary classification detection, in which the CLAHE enhancement and OCEAN enhancement methods had the accuracy and F1 Score with 97.42%, 97.19%, and 97.42%, 98.36%, respectively. DenseNet121 showed the best classification performance of four CNNs utilized in this study, as evidenced by the area under the receiver operating characteristic (ROC) curves (AUC). To verify the generalizability of the two enhancement methods, CLAHE and OCEAN enhancement methods were applied to the Magnetic Resonance Imaging (MRI) dataset of Alzheimer's disease, which had the accuracy and F1 Score with 98.15% , 98.15%, and 97.22%, 97.68%, respectively. Therefore, these simple and efficient data-augmentation methods effectively improve the performance of CNNs for diagnosing medical image, which can provide theoretical reference for physicians to diagnose the above two diseases, and advance the application of clinical medicine. © 2023 IEEE.

关键词： Magnetic resonance imaging

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Blackening failure of poly-α-olefin impregnated porous polymide due to the splitting of lubrication oil catalyzed by iron

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Friction 2024年第9期12卷 1969-1979页

作者： Pengfei SHI Yang YIN Shaohua ZHANG Diankai ZHANG Yuanyuan JIANG Yang WANG Ningning ZHOU Tao QING Jintao WU Linmao QIAN Jiyang ZHANG Lei CHEN Tribology Research Institute State Key Laboratory of Rail Transit Vehicle SystemSchool of Mechanical EngineeringSouthwest Jiaotong UniversityChengdu 610031China Beijing Key Laboratory of Long-life Technology of Precise Rotation and Transmission Mechanisms Beijing Institute of Control EngineeringBeijing 100094China Technology and Equipment of Rail Transit Operation and Maintenance Key Laboratory of Sichuan Province School of Mechanical EngineeringSouthwest Jiaotong UniversityChengdu 610031China

Lubrication failure accompanying with blackening phenomenon significantly reduces the long-running operational reliability of porous polymide(PPI)lubricated with poly-α-olefin(PAO)***,the effects of lubrication condition and counter-surface chemistry on the blackening failure of PAO impregnated PPI were studied through the comparison of the tribological tests against GCr15 steel ball and Al_(2)O_(3)ceramic ball with and without PAO oil *** products were found to be formed on the PAO impregnated PPI surface slid against steel ball or Al_(2)O_(3)ball added with iron nano-particles,but be absent under the conditions without iron or PAO *** analysis indicated that the iron-catalyzed splitting of PAO oil into small molecule alkanes and following the formation of black organic matter should be mainly responsible for the blackening *** dynamic(MD)simulations demonstrated that the iron facilitated the separation of hydrogen atom and the following broken of C–C bonds in PAO molecules,final resulting in the splitting of PAO oil.

关键词： porous polyimide poly-α-olefin oil friction-induced blackening phenomenon tribological performance ReaxFF MD simulation

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Integrated Active Suspension and Anti-Lock Braking Control for Four-Wheel-Independent-Drive Electric Vehicles

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Chinese Journal of Mechanical Engineering 2024年第1期37卷 87-98页

作者： Ze Zhao Lei Zhang Xiaoling Ding Zhiqiang Zhang Shaohua Li Liang Gu National Engineering Research Center for Electric Vehicles Beijing Institute of TechnologyBeijing 100081China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China

This paper presents an integrated control scheme for enhancing the ride comfort and handling performance of a four-wheel-independent-drive electric vehicle through the coordination of active suspension system(ASS)and anti-lock braking system(ABS).First,a longitudinal-vertical coupled vehicle dynamics model is established by integrating a road input *** the coupling mechanisms between longitudinal and vertical vehicle dynamics are *** ASS-ABS integrated control system is proposed,utilizing an H∞controller for ASS to optimize load transfer effect and a neural network sliding mode control for ABS ***,the effectiveness of the proposed control scheme is evaluated through comprehensive tests conducted on a hardware-in-loop(HIL)test *** HIL test results demonstrate that the proposed control scheme can significantly improve the braking performance and ride comfort compared to conventional ABS control methods.

关键词： Four-wheel-independent-drive electric vehicles Active suspension system(ASS) Anti-lock braking system(ABS) Vertical-longitudinal vehicle dynamics

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A Novel Approach for Solving Time-Varying Linear Equations and Its Application in Motion Tracking of Redundant Robots

A Novel Approach for Solving Time-Varying Linear Equations a...

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2023 International Conference on Frontiers of robotics and Software Engineering, FRSE 2023

作者： Yin, Hong Jin, Hongzhe Zhao, Jie Harbin Institute of Technology State Key Laboratory of Robotics and System Harbin China

ISBN: (纸本)9798350301113

Solving time-varying linear equations is a common problem in many fields. In this article, a novel approach is proposed based on the cost function constructed by the mixed error, which is made up of the residual error and its integration. The merits of the novel approach include high accuracy, noise immunity, and asymptotic convergence. Since the derivative information of time-varying signals is used in the proposed method, a proportional-integral differentiator is designed based on the mixed estimation error for the first derivative estimation. The proposed differentiator has a high degree of precision, asymptotic convergence, and no chattering. In addition, theoretical analyses prove the convergence of the proposed optimal strategy and differentiator. Simulation results validate the effectiveness and superiority of the proposed strategy and the designed differentiator. Finally, the proposed approach is employed in the motion tracking of redundant robots. © 2023 IEEE.

关键词： Errors

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Research on Digital Twin system Platform Framework and key Technologies of Unmanned Ground Equipment

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Complex system Modeling and Simulation 2024年第2期4卷 109-123页

作者： Kunyu Wang Lin Zhang Cheng Xu Han Lu Zhen Chen Hongbo Cheng Rui Guo the School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China the State Key Laboratory of Intelligent Manufacturing System Technology Beijing 100854China the Beijing Institute of Electronic System Engineering Beijing 100854China

As an emerging technology,digital twin is expected to bring novel application modes to the whole life cycle process of unmanned ground equipment,including research and development,design,control optimization,operation and maintenance,*** highly dynamic,complex,and uncertain characteristics of unmanned ground equipment and the battlefield environment also pose new challenges for digital twin *** from the new challenges faced by the digital twin of unmanned ground equipment,this paper designs a service-oriented cloud-edge-end collaborative platform architecture of the digital twin system of unmanned ground equipment,and further analyzes several key technologies supporting the implementation of the platform architecture.

关键词： unmanned ground equipment digital twin native cloud platform Modeling and Simulation(M&S) artificial intelligence

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Short-term Transmission Maintenance Scheduling Considering Network Topology Optimization

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Journal of Modern Power systems and Clean Energy 2022年第4期10卷 883-893页

作者： Weixin Zhang Bo Hu Kaigui Xie Changzheng Shao Tao Niu Jiahao Yan Lvbin Peng Maosen Cao Yue Sun State Key Laboratory of Power Transmission Equipment&System Security and New Technology at Chongqing University Chongqing 400044China

With the increasing penetration of renewable energy sources,transmission maintenance scheduling(TMS)will have a larger impact on the accommodation of wind ***,the more flexible transmission network topology owing to the network topology optimization(NTO)technique can ensure the secure and economic operation of power *** paper proposes a TMS model considering NTO to decrease the wind curtailment without adding control *** problem is formulated as a two-stage stochastic mixed-integer programming *** first stage arranges the maintenance periods of transmission *** second stage optimizes the transmission network topology to minimize the maintenance cost and system operation in different wind speed *** proposed model cannot be solved efficiently with off-theshelf solvers due to the binary variables in both ***,the progressive hedging algorithm is *** results on the modified IEEE RTS-79 system show that the proposed method can reduce the negative impact of transmission maintenance on wind accommodation by 65.49%,which proves its effectiveness.

关键词： Mixed-integer linear programming network topology optimization progressive hedging algorithm stochastic optimization transmission maintenance scheduling wind curtailment

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Dual-Arm Dynamic Planning with Considering Arm Reachability Constraint in Task Space 16th

Dual-Arm Dynamic Planning with Considering Arm Reachability ...

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16th International Conference on Intelligent robotics and Applications, ICIRA 2023

作者： Shu, Xin Fan, Xinyang Min, Kang Ji, Zhu Ni, Fenglei Liu, Hong State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China

ISBN: (纸本)9789819964888

This paper aims to address the issue of planning dual-arm motions in scenarios involving tracking dynamic desired pose and obstacle avoidance. In situations where dual-arm motion requires synchronous behavior, inflexible planning, encountering obstacles, and beyond-the-arm motion capability may lead to task failure. To overcome these issues, we propose a dynamic-system-based method for dual-arm collaborative planning. The method can coordinate the motions of dual arms while keeping synchronous behavior in tracking the moving target and avoiding obstacles. Meanwhile, we incorporate the reachability by modeling the motion boundary to ensure that the arms moving within the reachable space. The experiment successfully verified the above scenarios, showcasing its adaptability in dual-arm planning and its potential applicability in dual-arm applications such as transportation. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023.

关键词： Target tracking

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A Hierarchical Control Scheme for Active Power-assist Lower-limb Exoskeletons

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Journal of Bionic Engineering 2024年第5期21卷 2184-2198页

作者： Jing Deng Wenzheng Jiang Haibo Gao Yapeng Shi Mantian Li State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin150001HeilongjiangChina Shenzhen Academy of Aerospace Technology Shenzhen518063China Faculty of Computing Harbin Institute of TechnologyHarbin150001HeilongjiangChina Institute of Intelligent Manufacturing Technology Shenzhen Polytechnic UniversityShenzhen518055China

Effectively controlling active power-assist lower-limb exoskeletons in a human-in-the-loop manner poses a substantial chal-lenge,demanding an approach that ensures wearer autonomy while seamlessly adapting to diverse wearer *** paper introduces a novel hierarchical control scheme comprising five integral components:intention recognition layer,dynamics feedforward layer,force distribution layer,feedback compensation layer,as well as sensors and *** intention rec-ognition layer predicts the wearer's movement and enables wearer-dominant movement through integrated force and position *** force distribution layer effectively resolves the statically indeterminate problem in the context of double-foot support,showcasing flexible control *** dynamics feedforward layer mitigates the effect of the exoskeleton itself on ***,the feedback compensation layer provides reliable closed-loop *** approach mitigates abrupt changes in joint torques during frequent transitions between swing and stance phases by decomposed *** this innovative hierarchical control scheme on a hydraulic exoskeleton platform through a series of experiments,the results demonstrate its capability to deliver assistance in various modes such as stepping,squatting,and jumping while adapting seamlessly to different terrains.

关键词： Hierarchical control Active power-assist Exoskeleton robots Dynamics feedforward Force distribution Feedback compensation

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