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Understanding the friction behavior and surface characteristic in multiple ball-end milling passes of soft-brittle KH 2 PO 4 optics

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Tribology International 2025年 211卷

作者： Hongqin Lei Qiang Zhao Jian Cheng Linjie Zhao Mingjun Chen Qi Liu Dinghuai Yang Guang Chen State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 China School of Mechatronics Engineering Harbin Institute of Technology Harbin 150001 China Zhengzhou Research Institute Harbin Institute of Technology Zhengzhou 450000 China Department of Mechanical Engineering University of Bath Bath BA2 7AY United Kingdom

The utilization of a ball-end cutter to fabricate multi-layer microstructures is the preferred technique for eliminating surface defects in soft-brittle KH 2 PO 4 (KDP) optics. However, the previous milling pass would inevitably affect the tool-workpiece friction behavior and surface characteristics in the next milling process, which poses a great challenge to obtaining a defect-free microstructure surface. In this study, the effect of the multiple ball-end milling (MBEM) passes on material removal mode is explored according to tensile stress, residual stress and cutting force, which is verified from the perspectives of surface characteristics and roughness. The spindle speed, feed rate and milling depth of each-pass machining process are 50,000 r/min, 3 mm/s and 2 μm. The evaluation models of tool-workpiece friction behavior during the MBEM passes are developed, and the influence of soft-brittle materials on tool wear is analyzed. The results show that with when the number of milling passes ( i ) rises, the normalized plowing friction coefficient, tool-chip contact length and area increase, indicating that the tool-workpiece friction becomes severe. Meanwhile, with the rise in the i , the stress concentration area and surface roughness increase, which is attributed to the intensified tool-workpiece friction leading to an increase in cutting forces, thereby elevating the tensile stress exerted on the brittle KDP materials. When the i reaches 4, the brittle-plastic transition behavior occurs and edge chippings appear on the down-cut side. Furthermore, after the MBEM passes (the length of the milling path reaches 330 mm), there is no crack at the grain boundary, single grain spalling or even tool fracture on the CBN tool surface. Nevertheless, the low hardness of the KDP materials (2.18 GPa), coupled with the thermal softening effect, results in many chips adhering to the tool surface. The chemical composition of the built-up edge (BUE) consists of K, P and O. In part

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Micro-pores formation mechanism and porosity on the fatigue performance of dual laser-powder bed fusion of Ti6Al4V

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International Journal of Fatigue 2025年 199卷

作者： Guotai Li Peichen Hu Gang Chen Mingjun Chen Tianyu Yu State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin Heilongjiang 150001 China Key Laboratory of Micro-systems and Micro-structures Manufacturing Ministry of Education Harbin Heilongjiang 150001 China Institute of Electronic Engineering China Academy of Engineering Physics Mianyang Sichuan 621000 China

Porosity significantly impacts the fatigue performance and stability of dual laser additively manufactured metallic materials. This study presents a comparative analysis of the fatigue behavior of samples fabricated by single-laser powder bed fusion (SL-PBF) and dual-laser PBF (DL-PBF). It shows that porosity defects in the overlap region reduced the fatigue strength of DL-PBF samples by nearly 20 %. Micro-CT analysis revealed that micro-pores in the SL-PBF samples were predominantly located in the contour regions. Machining with a removal depth of 0.5 mm has effectively eliminated over 90 % of internal porosity defects. For monolithic specimens, increasing the sample size and reducing the layer-wise slice area can improve the sphericity of the internal defects (0.71 to 0.85) and reduce the porosity density (0.19 % to 0.011 %). Molecular dynamics simulations further examined the influence of pore size, spacing, and quantity on fatigue behavior. Larger pore sizes promote the formation of {11 2 ¯ 1} < 1 ¯ 1 ¯ 26> twin variants, as the pore diameter increased from 20 Å to 80 Å, the proportion of variants structure increased from 3.6 % to 11.5 %. Fatigue failure initiated from a single pore, with stress propagating towards a distant pore, forming crack paths. Stress was relieved along these crack trajectories, leading to secondary crack branches that spread into low-stress zones around other defects, which resulted in fatigue cracks with vein-like morphologies. This work provides systematic insights into the fatigue degradation mechanisms induced by porosity and offers actionable strategies for improving the fatigue resistance of multi-laser PBF components through process control.

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Bio-robotics research for non-invasive myoelectric neural interfaces for upper-limb prosthetic control: a 10-year perspective review

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National Science Review 2023年第5期 38-58页

作者：江宁陈晨何家源孟建军潘立志苏世勇朱向阳 National Clinical Research Center for Geriatrics West China Hospitaland Med-X Center for ManufacturingSichuan University State Key Laboratory of Mechanical System and Vibration and Institute of RoboticsShanghai Jiao Tong University Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education School of Mechanical EngineeringTianjin University Institute of Neuroscience Université Catholique Louvain

A decade ago,a group of researchers from academia and industry identified a dichotomy between the industrial and academic state-of-the-art in upper-limb prosthesis control,a widely used bio-robotics *** proposed that four key technical challenges,if addressed,could bridge this gap and translate academic research into clinically and commercially viable *** challenges are unintuitive control schemes,lack of sensory feedback,poor robustness and single sensor ***,we provide a perspective review on the research effort that occurred in the last decade,aiming at addressing these *** addition,we discuss three research areas essential to the recent development in upper-limb prosthetic control research but were not envisioned in the review 10 years ago:deep learning methods,surface electromyogram decomposition and open-source *** conclude the review,we provide an outlook into the near future of the research and development in upper-limb prosthetic control and beyond.

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Time-Optimal Trajectory Planning Based on Dynamics for Industrial Robot

Time-Optimal Trajectory Planning Based on Dynamics for Indus...

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Automation, Control and robotics engineering (CACRE), International Conference on

作者： Rundong Wang Minxiu Kong Yanchun Cheng Marco Castellani School of Mechatronics Engineering Harbin Institute of Technology State Key Laboratory of Robotics and System University of Birmingham Department of Mechanical Engineering

ISBN: (数字)9781728198880

ISBN: (纸本)9781728198897

Given the trajectory of the industrial robot in Cartesian space, the existing methods only consider the kinematic constraints when optimizing the time trajectory planning, and ignore the maximum driving ability of the motor, which is likely to cause an overrun alarm and greatly reduce the trajectory accuracy. Therefore, this paper studies the timeoptimal trajectory planning algorithm based on dynamics. Firstly, the algorithm discretizes the path, calculates the Cartesian coordinates of each discrete point and the differential about the path length. Then, this algorithm considers the constraints of dynamics and kinematics, uses the principle of linear programming, recursively calculates the upper limit value of speed and the maximum acceleration value at each discrete point, and calculates the speed value at each discrete point and keeps it within its allowable ranges. Finally, this algorithm uses the speed to calculate the corresponding time of each discrete point, and according to the interpolation period, outputs the path position of each period, the position and orientation in the Cartesian space and joint parameters. The MATLAB program is written to verify the feasibility and efficiency of the algorithm.

关键词： industrial robot trajectory planning time-optimal dynamics multiple constraints

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Design and preliminary testing of a piezoelectric-based sole energy harvester

Design and preliminary testing of a piezoelectric-based sole...

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IEEE International Conference on robotics and Biomimetics

作者： Yidi Wang Xuan Zhao Qiuyu Shi Haisu Liao Xinyu Wu Fei Gao Guangdong Provincial Key Laboratory of Robotics and Intelligent System Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Shenzhen China Guangdong-Hong Kong-Macao Joint Laboratory of Human-Machine Intelligence-Synergy Systems Shenzhen China Department of Mechanical and Automation Engineering The Chinese University of Hong Kong Shatin Hong Kong China

ISBN: (纸本)9781665481106

Harvesting energy from the human body to replenish existing energy sources is receiving substantial attention. Recently scientists have been focusing on harvesting biomechanical energy from human feet during walking. This paper develops a piezoelectric-based sole energy harvester that is designed to be worn on the bottom of shoes to harvest energy, thus powering wearable electronic devices. Specifically, a cam with piezoelectric(PZT) stacks is mounted on the heel to scavenge energy during the heel strike. The cam can change the input's direction from the vertical direction to the horizontal direction. In addition, the output power of this part can be optimized or improved by generating a specified cam profile. A bimorph piezoelectric plate is installed on the forefoot to convert the toes' bending deformation into electricity. Herein, piezoelectric Macro Fiber Composites (MFC) are employed to capture the large deformation. Preliminary testing on a healthy subject is conducted to validate this design. The average power output of the harvester is 8.83 m W.

关键词： Legged locomotion Biomechanics Wearable computers Bending Optical fiber devices Piezoelectric devices Optical fiber testing

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Active Virtual Mass Micro-Vibration Isolation Control Method based on Two-Parameter Acceleration Feedback

Active Virtual Mass Micro-Vibration Isolation Control Method...

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International Conference on Electronic Measurement and Instruments, ICEMI

作者： Jing Wang Lei Wang Junzhong Li Yuanyuan Yang Yujian Bian Bin Zhou School of instrumentation science and engineering Harbin Institute of Technology Harbin China Shenzhen Key Laboratory of Minimally Invasive Surgical Robotics and System Chinese Academy of Sciences Shenzhen China Heilongjiang Research Institute of Territory's Spatial Planning Harbin China

ISBN: (纸本)9781665444927

External interference is an important factor affecting the accuracy and stability of precision equipment. An active micro-vibration isolation control method is proposed and used in active vibration control to suppress external interference in this paper. This method is based on two-parameter acceleration feedback, which splits the acceleration feedback gain into two parameters, one on the front path and one on the feedback path. Compared with the traditional acceleration feedback, the proposed method not only increases the virtual mass of the system to reduce the natural frequency, but also suppresses the excessive motor output in the vibration isolation system simultaneously. Simulation results proved the effectiveness of the proposed two-parameter acceleration feedback control method in preventing excessive motor output, and experimental results confirm its capacity to reduce the natural frequency of the system.

关键词： Vibrations Simulation Instruments Interference Vibration control Stability analysis Feedback control

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Nonequilibrium Effects on Rapid Directional Solidification Microstructures During Additive Manufacturing: A Quantitative Phase Field Study

SSRN

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SSRN 2024年

作者： Li, Leiji Xiao, Fei Li, Zhu He, Shiyu Liu, Yang Cai, Xiaorong Hou, Ruihang Zhou, Ying Zuo, Shungui Zhang, Chongfeng Gao, Jinzhong Shen, Xiaopeng Zhu, Tianchi Gu, Yijia Jin, Xuejun State Key Lab of Metal Matrix Composite School of Materials Science and Engineering Shanghai Jiao Tong University 800 Dong Chuan Road Shanghai200240 China Institute of Medical Robotics Shanghai Jiao Tong University Shanghai200240 China National Key Laboratory of Aerospace Mechanism Aerospace System Engineering Shanghai 3805 Jin Du Road Shanghai201108 China Department of Materials Science and Engineering Missouri University of Science and Technology RollaMO65409 United States National Engineering Research Center of Advanced Magnetic Resonance Technologies for Diagnosis and Therapy School of Materials Science and Engineering Shanghai Jiao Tong University 800 Dong Chuan Road Shanghai200240 China Department of Materials Science and Engineering Graduate School of Engineering Osaka University 2-1 Yamada-oka Osaka Suita565-0871 Japan Shanghai Key Laboratory of Materials Laser Processing and Modification China

Fusion-based metal additive manufacturing (AM) is a technology that builds objects layer by layer, with rapid solidification referring to the quick transition of material from liquid to solid. During this process, solute trapping, a nonequilibrium effect characterized by velocity-dependent partition coefficient, significantly influences microstructure kinetics, morphology, and phase formation. This study utilizes the latest quantitative phase field (PF) model to systematically investigate the solute trapping, solute drag, and their effects on pattern formation during rapid solidification at velocities relevant to AM, in both one and two dimensions. Under different temperature gradients and pulling velocities, we observed that the growth mode transits from planar to cellular to dendritic, then back to cellular, and finally to planar, which is consistent with classic solidification theory. A solidification microstructure selection map is constructed based on PF simulations. Furthermore, we compared primary dendritic/cell spacing calculated by the PF model with theoretical models. The simulated morphologies and arm spacing showed good agreement with experimental observations for Al-4Si and Ti-20Nb alloys during rapid solidification. These results demonstrate the potential of the PF model for predicting and controlling microstructure formation under rapid solidification conditions in the melt pool of AM processes. © 2024, The Authors. All rights reserved.

关键词： Morphology

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Finally! Insights into the ARCHES Lunar Planetary Exploration Analogue Campaign on Etna in summer 2022 73

Finally! Insights into the ARCHES Lunar Planetary Exploratio...

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73rd International Astronautical Congress, IAC 2022

作者： Wedler, Armin Müller, Marcus G. Schuster, Martin J. Durner, Maximilian Lehner, Peter Dömel, Andreas Vayugundla, Mallikarjuna Steidle, Florian Sakagami, Ryo Meyer, Lukas Smisek, Michal Stürzl, Wolfgang Schmitz, Nicole Vodermayer, Bernhard Prince, Andre F. Ehreiser, Anouk Staudinger, Emanuel Pöhlmann, Robert Zhang, Siwei Hellerer, Matthias Lichtenheldt, Roy Franke, Dennis Pignède, Antoine Schindler, Walter Schütt, Manuel Rebele, Bernhard Boerdijk, Wout Giubilato, Riccardo Reill, Josef Kuhne, Moritz Lee, Jongseok Schröder, Susanne Frohmann, Sven Seel, Fabian Dietz, Enrico Triebel, Rudolph Lii, Neal Y. Bischoff, Esther Braun, Christian Kille, Sean Wormnes, Kjetil Pereira, Aaron Carey, William Rossi, Angelo P. Thomsen, Laurenz Graber, Thorsten Kruger, Thomas Börner, Anko Bussmann, Kristin Paar, Gerhard Bauer, Arnold Völk, Stefan Rauer, Heike Hübers, Heinz-Wilhelm Bals, Johann Hohmann, Sören Asfour, Tamim Foing, Bernhard Albu-Schäffer, Alin Olimpiu Institute of Robotics and Mechatronics Münchener Str. 20 Weßling82234 Germany Institute of Optical Sensor Systems Rutherfordstr. 2 Berlin12489 Germany Institute of System Dynamics and Control Münchener Str. 20 Weßling82234 Germany Institute of Communications and Navigation Münchener Str. 20 Weßl82234 Germany Institute of Planetary Research Rutherfordstr. 2 Berlin12489 Germany Mobile Rocket Base Münchener Str. 20 Weßl82234 Germany Joanneum Research Steyrergasse 17 GrazA-8010 Austria Solenix Engineering GmbH Spreestr. 3 Darmstadt64295 Germany ESTEC Noordwijk Netherlands University of Leiden Netherlands Institute of Control Systems Kaiserstr. 12 Karlsruhe76131 Germany Kaiserstr. 12 Karlsruhe76131 Germany Jacobs University Bremen Planetary Science Campus Ring 1 Bremen28759 Germany

This paper summarises the first outcomes of the space demonstration mission of the ARCHES project which could have been performed this year from 13 june until 10 july on Italy's Mt. Etna in Sicily. After the second postponement related to COVID from the initially for 2020 planed campaign, we are now very happy to report, that the whole campaign with more than 65 participants for four weeks has been successfully conduced. In this short overview paper, we will refer to all other publication here on IAC22. This paper includes an overview of the performed 4-week campaign and the achieved mission goals and first results but also share our findings on the organisational and planning aspects. Copyright © 2022 by the International Astronautical Federation (IAF). All rights reserved.

关键词： robotics

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A Spray Path Planning Algorithm based on 3D Point Cloud 3

A Spray Path Planning Algorithm based on 3D Point Cloud

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3rd IEEE Advanced Information Management, Communicates, Electronic and Automation Control Conference, IMCEC 2019

作者： Tong, Ning Kong, Minxiu Xu, Shengrun Harbin Institute of Technology School of Mechatronics Engineering China State Key Laboratory of Robotics and System Harbin China

ISBN: (纸本)9781728105130

Robotic spray path planning for complex surface has always been a challenging problem, especially when it comes to flexible manufacturing system. This paper presents a new method to plan the spray path based on the point cloud obtained by vision sensors. In order to select the direction of slice adaptively, a method based on principal component analysis (PCA) is adopted to calculate the dominant eigenvector of point cloud. The intersection algorithm is also discussed to obtain points for constructing spraying path. The normal vector calculation and sorting problem of slice points are also solved. The experimental results show that the proposed path planning method can automatically generate the spraying path according to the surface of spray target. This method can also be extended to other applications. © 2019 IEEE.

关键词： Principal component analysis

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Long and Short-Term Constraints Driven Safe Reinforcement Learning for Autonomous Driving

arXiv

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arXiv 2024年

作者： Hu, Xuemin Chen, Pan Wen, Yijun Tang, Bo Chen, Long School of Artificial Intelligence Hubei University Wuhan430062 China Key Laboratory of Intelligent Sensing System and Security Hubei University Ministry of Education Hubei Wuhan430062 China Department of Electrical and Computer Engineering Worcester Polytechnic Institute WorcesterMA01609 United States State Key Laboratory of Multimodal Artificial Intelligence Systems State Key Laboratory of Management and Control for Complex Systems Chinese Academy of Sciences Beijing100190 China WAYTOUS Inc. Beijing100083 China Shenzhen518107 China Institute of Artificial Intelligence and Robotics Xi'an Jiaotong University Xi’an710049 China

Reinforcement learning (RL) has been widely used in decision-making and control tasks, but the risk is very high for the agent in the training process due to the requirements of interaction with the environment, which seriously limits its industrial applications such as autonomous driving systems. Safe RL methods are developed to handle this issue by constraining the expected safety violation costs as a training objective, but the occurring probability of an unsafe state is still high, which is unacceptable in autonomous driving tasks. Moreover, these methods are difficult to achieve a balance between the cost and return expectations, which leads to learning performance degradation for the algorithms. In this paper, we propose a novel algorithm based on the long and short-term constraints (LSTC) for safe RL. The short-term constraint aims to enhance the shortterm state safety that the vehicle explores, while the long-term constraint enhances the overall safety of the vehicle throughout the decision-making process, both of which are jointly used to enhance the vehicle safety in the training process. In addition, we develop a safe RL method with dual-constraint optimization based on the Lagrange multiplier to optimize the training process for end-to-end autonomous driving. Comprehensive experiments were conducted on the MetaDrive simulator. Experimental results demonstrate that the proposed method achieves higher safety in continuous state and action tasks, and exhibits higher exploration performance in long-distance decision-making tasks compared with state-of-the-art methods. Copyright © 2024, The Authors. All rights reserved.

关键词： Lagrange multipliers

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