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

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.

关键词： Dual-laser powder bed fusion High cycle fatigue Molecular dynamics Porosity Ti6Al4V

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Conditional Generative Models for Simulation of EMG During Naturalistic Movements

arXiv

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arXiv 2022年

作者： Ma, Shihan Clarke, Alexander Kenneth Maksymenko, Kostiantyn Deslauriers-Gauthier, Samuel Sheng, Xinjun Zhu, Xiangyang Farina, Dario The Department of Bioengineering Imperial College London United Kingdom The State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai China The Meta Robotics Institute Shanghai Jiao Tong University Shanghai China Neurodec Sophia Antipolis France Inria Centre Université Côte d’Azur Nice France

Numerical models of electromyographic (EMG) signals have provided a huge contribution to our fundamental understanding of human neurophysiology and remain a central pillar of motor neuroscience and the development of human-machine interfaces. However, whilst modern biophysical simulations based on finite element methods are highly accurate, they are extremely computationally expensive and thus are generally limited to modelling static systems such as isometrically contracting limbs. As a solution to this problem, we propose a transfer learning approach, in which a conditional generative model is trained to mimic the output of an advanced numerical model. To this end, we present BioMime, a conditional generative neural network trained adversarially to generate motor unit activation potential waveforms under a wide variety of volume conductor parameters. We demonstrate the ability of such a model to predictively interpolate between a much smaller number of numerical model’s outputs with a high accuracy. Consequently, the computational load is dramatically reduced, which allows the rapid simulation of EMG signals during truly dynamic and naturalistic movements. Copyright © 2022, The Authors. All rights reserved.

关键词： Numerical models

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An Evolutionary Game based Secure Clustering Protocol with Fuzzy Trust Evaluation and Outlier Detection for Wireless Sensor Networks

arXiv

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arXiv 2022年

作者： Yang, Liu Lu, Yinzhi Yang, Simon X. Zhong, Yuanchang Guo, Tan Liang, Zhifang The School of Communication and Information Engineering Chongqing University of Posts and Telecommunications Chongqing China The Advanced Robotics and Intelligent Systems Laboratory School of Engineering University of Guelph GuelphONN1G2W1 Canada The State Key Laboratory of Power Transmission Equipment & System Security and New Technology School of Electrical Engineering Chongqing University Chongqing400044 China

Trustworthy and reliable data delivery is a challenging task in Wireless Sensor Networks (WSNs) due to unique characteristics and constraints. To acquire secured data delivery and address the conflict between security and energy, in this paper we present an evolutionary game based secure clustering protocol with fuzzy trust evaluation and outlier detection for WSNs. Firstly, a fuzzy trust evaluation method is presented to transform the transmission evidences into trust values while effectively alleviating the trust uncertainty. And then, a K-Means based outlier detection scheme is proposed to further analyze plenty of trust values obtained via fuzzy trust evaluation or trust recommendation. It can discover the commonalities and differences among sensor nodes while improving the accuracy of outlier detection. Finally, we present an evolutionary game based secure clustering protocol to achieve a trade-off between security assurance and energy saving for sensor nodes when electing for the cluster heads. A sensor node which failed to be the cluster head can securely choose its own head by isolating the suspicious nodes. Simulation results verify that our secure clustering protocol can effectively defend the network against the attacks from internal selfish or compromised nodes. Correspondingly, the timely data transfer rate can be improved significantly. © 2022, CC BY.

关键词： Sensor nodes

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Recent advances on human-robot interface of wheelchair-mounted robotic arm

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Recent Patents on Mechanical Engineering 2019年第1期12卷 45-54页

作者： Chi, Mingshan Yao, Yufeng Liu, Yaxin Zhong, Ming State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China Rongcheng Campus Harbin University of Science and Technology Rongcheng264300 China Industrial Research Institute of Robotics and Intelligent Equipment Weihai264209 China

Background: Wheelchair mounted robotic arm is a typical assistive robot, which is widely used to help the elders and the disabled to complete the activities of daily life. But limited by the restrictions of the users’ athletic ability and cognitive ability, how to flexibly manipulate such robot is still a problem in front of them. The human-computer interaction technology is the core technology of the robot. Its performance directly affects the user's acceptability, satisfaction and promotion of intelligent wheelchairs. Objective: The study aims to give a general summary of recent human-robot interface of wheelchair mounted robotic arm and introduce their respective characteristics. Methods: Based on various patents and research developments about the human-robot interface of the assistive robot at home and abroad, this paper puts forward the basic principle of designing the human-robot interaction mode, divides the man-robot interface into two categories based on the perspective of user control robot arm, and describes in detail, the typical human-robot interface and its related characteristics contained in each classification. Results: The development trends of the human-robot interface in future are predicted, so as to provide some research reference for the related scientific researchers. Conclusion: Wheelchair mounted robotic arm has important practical significance. Further improvements are needed in the design of the human-robot interface. It can effectively improve the operation performance of the WMRA, and take full advantage of the user’s existing movement ability to meet the requirement of dominating the control process. Furthermore, these improvements in the human-robot interface will allow more and more users to accept the WMRA, manipulate the WMRA, and enjoy improvements in the quality of their life for these assistive robots. © 2019 Bentham Science Publishers.

关键词： Human robot interaction

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Redistributing Controller Orders to Increase Positioning Bandwidth in Nanopositioners

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IFAC-PapersOnLine 2021年第21期54卷 97-102页

作者： Adedayo K. Babarinde Linlin Li Jakub Kuncak LiMin Zhu Sumeet S. Aphale Artificial Intelligence Robotics and Mechatronic Systems Group School of Engineering University of Aberdeen Aberdeen AB24 3UE UK State Key Laboratory of Mechanical System and Vibration School of Mechanical Engineering Shanghai Jiao Tong University Shanghai 200240 China

Integer-order damping and tracking controllers are typically used in tandem to overcome resonance and hysteresis induced positioning errors in piezo-actuated nanopositioners. This paper takes a novel approach of strategically redistributing the controller orders to achieve significant positioning bandwidth improvement, without any significant increase in the design complexity. The Positive Position Feedback (PPF) controller combined with a suitably gained Integral tracking controller is used as a candidate to demonstrate the efficacy of the proposed technique. The resulting fractional-order PPF damping and Integral tracking controllers result in increasing the overall positioning bandwidth of the closed-loop system by 37%; and subsequent improvement in positioning accuracy while tracking high-frequency triangular trajectories.

关键词： Nanopositioners piezoelectric actuator positive position feedback tracking control fractional-order control

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XNORAM: An Efficient Computing-in-Memory Architecture for Binary Convolutional Neural Networks with Flexible Dataflow Mapping

XNORAM: An Efficient Computing-in-Memory Architecture for Bi...

引用

IEEE International Conference on Artificial Intelligence Circuits and systems (AICAS)

作者： Shiwei Liu Haozhe Zhu Chixiao Chen Lihua Zhang C.-J. Richard Shi State Key Laboratory of ASIC and System Shanghai Engineering Research Center for AI & Robotics Fudan University Shanghai

ISBN: (数字)9781728149226

ISBN: (纸本)9781728149233

In this paper, an energy-efficient computing-in-memory architecture for binary convolutional neural networks, called XNORAM, is proposed. The XNORAM employs 6T feature cells and 10T weight cells to form one XNORAM column. Multiplexed XNOR operations are embedded in each column. To address the data reuse in convolutional neural networks, flexible dataflow mapping is supported on XNORAM to minimize the external data access. To verify the architecture, we design a 4-KB XNORAM prototype in 65nm CMOS technology. It achieves a throughput of 18. 5GOPs at 100-MHz clock rate and 1.0-V power supply. XNOR-AlexNet is performed on the design achieving 39.86 TOPS/W and 4.63 GOPS/KB utilization with only 1.3% accuracy loss comparing to the original XNOR-Net result on GPUs.

关键词： Convolution Computer architecture Prototypes Topology Convolutional neural networks CMOS technology Throughput

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Design and Experiment of a Compact Cable-Driving Module for Reconfigurable Cable-Driven Parallel Robots

Research Square

引用

Research Square 2020年

作者： Yuan, Han An, Hao Zhang, Yongqing Xu, Wenfu Shenzhen518055 China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150080 China

Cable-driven parallel robots (CDPRs) have the characteristics of reconfigurability, which endows CDPRs with flexible workspace, freely configurable degrees of freedom and various configurations, greatly expanding their range of applications. Modular design provides great convenience and feasibility for the realization of reconfiguration, which is a key issue of reconfiguration research. However, most existing CDPRs have problems of low modularity and low system integration, which brings inconvenience to the realization of reconfiguration. In this paper, a highly integrated and high precision cable-driving module is designed, which can accurately control the length and tension of the cable. In addition, experimental verification is performed. The single-module experiment shows that the module has good ability for cable length and cable tension control. The cable length control error is less than 0.2mm, and the cable tension control error is less than 0.8N. Furthermore, based on the proposed module, a CDPR with 8 cables and 6 degrees of freedom is constructed rapidly. The open-loop tracking error of the robot is measured by laser tracker. Results show that the tracking error is less than 4.5mm and the Root-Mean-Square-Error (RMSE) is 2.1mm. Besides, the compliance control experiment of the robot shows that the tracking error in impedance control mode is less than 2mm, and the RMSE is 0.95mm, and the drag force in teaching mode is less than 2.5N, which demonstrates good follow-up performance. The proposed compact cable-driving module with high precision could be useful for the design and rapid construction of reconfigurable CDPRs. © 2020, CC BY.

关键词： Cables

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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

引用

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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Corrigendum to “Drill-soil penetration model and its application to lunar exploration” [Adv. Space Res. 70(11) (2022) 3436–3449]

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Advances in Space Research 2023年第8期71卷 3532-3532页

作者： Ye Tian Jiahang Zhang Weiwei Zhang Boyi Xu Zhangqing Duan School of Light Industry Harbin University of Commerce Harbin 150028 PR China The State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 PR China

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A Synthetic Framework for Evaluating and Designing an Anthropomorphic Prosthetic Hand

引用

Journal of Bionic Engineering 2018年第1期15卷 69-82页

作者： Li Jiang Yuan Liu Dapeng Yang Hong Liu State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150080 China

The mimic of aesthetics, fianction, and rehabilitation application makes the prosthetic hand design an interdisciplinary, synthetic work. Prosthetic hands should be designed in a comprehensive consideration with a synthetic framework from multiple areas. In this case, a synthetic framework containing 12 anthropomorphism indexes is established and utilized to understand the human hand characteristic and quantifiably evaluate the anthropomorphism of a prosthetic hand. Our quantified evaluation results show that a Global Anthropomorphic Score （GAS） of the current commercial prosthetic hands is only 45.2%. The compliance, coupling speed ratio and configuration of the Degrees Of Freedom （DOF） are found to be the lowest three anthropomorphism evaluation indexes in all 12 indexes. In addition, a design priority is proposed based on the quantified evaluation results and contributes to a prosthetic hand design. Moreover, our correlation analysis results between each index and GAS show that, compared with the conventional evaluation index-grasp gesture, the rotation axis distribution index has a stronger distinguishing capability to the hand performance. Finally, a flowchart of prosthetic hand design was presented for a designer to design a prosthetic hand with a high anthropomorphism.

关键词： prosthetic hand anthropomorphism quantified evaluation bionic design mechanical implementation rehabilitation

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