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SSRN 2022年

作者： Kaner, Ngeywo Tolbert Wei, Yadong Raza, Ali Yang, Jianqun Li, Xingji Li, Weiqi Jiang, YongYuan Wei Quan, Tian School of Physics Harbin Institute of Technology Harbin150001 China School of Materials Science and Engineering Harbin Institute of Technology Harbin150001 China Technology Innovation Center of Materials and Devices at Extreme Environment Harbin Institute of Technology Harbin150001 China 1-Km Main Daska Road Punjab Sialkot51040 Pakistan State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Xi’an710024 China Key Lab of Micro-Optics and Photonic Technology of Heilongjiang Province Harbin150001 China Key Laboratory of Micro-Nano Optoelectronic Information System Ministry of Industry and Information Technology Harbin150001 China Collaborative Innovation Center of Extreme Optics Shanxi University Taiyuan030006 China Chongqing Key Laboratory of Theoretical and Computational Chemistry College of Chemistry and Chemical Engineering Chongqing University Chongqing401331 China

Shift photovoltaic current (SPC) in polar non-centrosymmetric materials has recently emerged as a promising candidate for the next generation photovoltaic devices in which Shockley-Queisser limits are fully overcome. Here, we apply first principles calculations to predict colossal SPC in the slide bilayers of 2D h -BN and β-GeS vdW homostructures. The large SPC in slide bilayers h -BN and β-GeS reaches 49.3 µAV-2 and 130µ µAV-2 , respectively, in the ultra-violet (UV) region. Increasing the number of layers is further implemented to tune the band structure of the two homostructures. Consequently, giant SPC peaks about 3 times larger than those of the 2-layers is predicted at photon energies 7.40 eV and 5.95 eV in the 5-layers of h -BN and β-GeS, respectively. The two homostructures may thus be promising building blocks for next-generation shift current devices. These findings also suggest layering as a possible convenient approach of enhancing and also tuning the SPC output in thin layered materials. © 2022, The Authors. All rights reserved.

关键词： Van der Waals forces

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Long-term Dependency for 3D Reconstruction of Freehand Ultrasound Without External Tracker

arXiv

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arXiv 2023年

作者： Li, Qi Shen, Ziyi Li, Qian Barratt, Dean C. Dowrick, Thomas Clarkson, Matthew J. Vercauteren, Tom Hu, Yipeng The UCL Centre for Medical Image Computing The Wellcome/EPSRC Centre for Interventional and Surgical Sciences Department of Medical Physics and Biomedical Engineering University College London LondonWC1E 6BT United Kingdom State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China School of Biomedical Engineering & Imaging Sciences King’s College London LondonWC2R 2LS United Kingdom

Objective: Reconstructing freehand ultrasound in 3D without any external tracker has been a longstanding challenge in ultrasound-assisted procedures. We aim to define new ways of parameterising long-term dependencies, and evaluate the performance. Methods: First, long-term dependency is encoded by transformation positions within a frame sequence. This is achieved by combining a sequence model with a multi-transformation prediction. Second, two dependency factors are proposed, anatomical image content and scanning protocol, for contributing towards accurate reconstruction. Each factor is quantified experimentally by reducing respective training variances. Results: 1) The added long-term dependency up to 400 frames at 20 frames per second (fps) indeed improved reconstruction, with an up to 82.4% lowered accumulated error, compared with the baseline performance. The improvement was found to be dependent on sequence length, transformation interval and scanning protocol and, unexpectedly, not on the use of recurrent networks with long-short term modules;2) Decreasing either anatomical or protocol variance in training led to poorer reconstruction accuracy. Interestingly, greater performance was gained from representative protocol patterns, than from representative anatomical features. Conclusion: The proposed algorithm uses hyperparameter tuning to effectively utilise long-term dependency. The proposed dependency factors are of practical significance in collecting diverse training data, regulating scanning protocols and developing efficient networks. Significance: The proposed new methodology with publicly available volunteer data and code1 for parametersing the long-term dependency, experimentally shown to be valid sources of performance improvement, which could potentially lead to better model development and practical optimisation of the reconstruction application. © 2023, CC BY.

关键词： Ultrasonics

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Dual-channel quantum meta-hologram for display

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Advanced Photonics Nexus 2024年第1期3卷 86-92页

作者： Yubin Fan Hong Liang Yuhan Wang Shufan Chen Fangxing Lai Mu Ku Chen Shumin Xiao Jensen Li Din Ping Tsai City University of Hong Kong Department of Electrical EngineeringHong KongChina City University of Hong Kong Centre for BiosystemsNeuroscienceand NanotechnologyHong KongChina City University of Hong Kong The State Key Laboratory of Terahertz and Millimeter WavesHong KongChina The Hong Kong University of Science and Technology Department of PhysicsHong KongChina The Hong Kong University of Science and Technology IAS Center for Quantum TechnologiesHong KongChina Harbin Institute of Technology(Shenzhen) Ministry of Industry and Information Technology Key Lab of Micro-Nano Optoelectronic Information SystemGuangdong Provincial Key Laboratory of Semiconductor Optoelectronic Materials and Intelligent Photonic SystemsShenzhenChina Pengcheng Laboratory ShenzhenChina

Quantum technologies rely on creating and manipulating entangled sources,which are essential for quantum information,communication,and *** integrating quantum technologies and all-dielectric metasurfaces,the performance of miniature display devices can be enhanced to a higher *** display technology,such as virtual reality display,has achieved original commercial success,and was initially applied to immersive games and interactive *** the consumer market has quickly adopted this technology,several areas remain for improvement,including concerns around bulkiness,dual-channel display,and noise ***,we experimentally realize a quantum meta-hologram concept demonstration of a miniature *** fabricate an ultracompact meta-hologram based on 1μm thick titanium dioxide(TiO_(2)).The meta-hologram can be remotely switched with heralding technique and is robust against noise with the quantum entangled *** platform can alter the miniature display channel by manipulating heralding photons’polarization,removing speckles and multiple reflective light noise,improving imaging contrast,and potentially decreasing device *** contrast increases from 0.36 dB under speckle noise influences to 6.8 dB in quantum correlation *** approach has the potential to miniaturize quantum displays and quantum communication devices.

关键词： quantum meta-hologram display metasurface dual channel

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

Research Square

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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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基于Watt连杆的可重复使用运载火箭腿式可展开着陆机构——原理、原型设计和实验验证（英文）

引用

Engineering 2023年第1期 120-133页

作者：于海涛田保林闫振高海波张宏剑吴会强王英超石玉红邓宗全 State Key Laboratory of Robotics and Systems Harbin Institute of Technology Beijing Institute of Aerospace Systems Engineering

可重复使用运载火箭是降低太空运输成本的一种新途径。着陆机构是可重复使用运载火箭的重要组成部分，起到着陆支撑和吸收冲击的作用。本文提出了一种新型的可展开着陆机构（LDLM）。采用Watt-Ⅱ型六杆机构，利用连杆变分法得到优选构...

可重复使用运载火箭是降低太空运输成本的一种新途径。着陆机构是可重复使用运载火箭的重要组成部分，起到着陆支撑和吸收冲击的作用。本文提出了一种新型的可展开着陆机构（LDLM）。采用Watt-Ⅱ型六杆机构，利用连杆变分法得到优选构型。本文建立了多目标优化范式，使得可展开着陆机构具有着陆支撑区域大、重量轻、连杆内力合理等优点，在此基础上，利用NSGA-Ⅱ进化算法得到了可展开式着陆机构设计的最优尺寸参数。本文研制了全功能可重复使用运载火箭缩比样机，通过集成重力控制的展开方案以促进展开动作，避免全范围驱动，采用双重锁紧机构以提高展开状态时结构的可靠性，采用多级铝蜂窝缓冲器提供可靠的减震性能。实验结果表明，所提出的可展开式着陆机构能够提供快速平稳的展开（持续时间小于1.5 s），且对舱体的姿态扰动较小（偏航和俯仰波动小于6°）。此外，它在0.2 m自由落体测试中提供了足够的冲击衰减（加速度峰值小于10 g）。所提出的可展开着陆机构可作为未来可重复使用运载火箭潜在的腿式起落架替代方案。

关键词：

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Automatic Recognition of Social Engagement for Children with Autism Spectrum Disorder

Automatic Recognition of Social Engagement for Children with...

引用

IEEE International Conference on systems, Man and Cybernetics

作者： Xinming Wang Xiangdong Zhang Zhiyong Wang Wei Nie Hanlin Zhang Xiu Xu Honghai Liu State Key Laboratory of Robotics and Systems School of Mechanical and Automation Harbin Institute of Technology (Shenzhen) Shenzhen China Lishui Maternity and Child Health Care Hospital Center of Medical Prenatal Diagnosis Lishui China Department of Child Health Care Children's Hospital of Fudan University Shanghai China School of Computing University of Portsmouth Portsmouth U.K Peng Cheng Laboratory Shenzhen China

ISBN: (数字)9781665410205

ISBN: (纸本)9781665410212

Estimating children's engagement levels improves their understanding of their social behaviors, since they can reflect their devotion to social interaction with others. This paper proposes an automatic method to recognize children's engagement levels in a triadic social interaction context. First, an overall metric function containing behavior, cognition, and affective dimensions is proposed to estimate children's multidimensional engagement levels. Then, the automatic feature extraction method based on gaze estimation, facial expression recognition, pose estimation, and object recognition models is illustrated to extract features to compute the engagement levels. Videos of 24 children, including 13 children with autism spectrum disorder (ASD), in triadic social interaction were collected for the engagement recognition experiment and cross-group analysis. The experimental results validate the effectiveness of the proposed automatic feature extraction method compared to human observations. Cross-group analyses revealed significant differences in affective engagement between children with ASD and typical developmental (TD) children.

关键词： Measurement Autism Computer vision Computational modeling Face recognition Pose estimation Feature extraction Object recognition Cybernetics Videos

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A visual calibration method of monocular camera and pan-tilt for mobile robots

A visual calibration method of monocular camera and pan-tilt...

引用

2019 IEEE International Conference on Real-Time Computing and robotics, RCAR 2019

作者： Sun, Jingwen Zhao, Lijun Wang, Ke Zhao, Yujia Meng, Xiangbo Mao, Chuwei Wang, Jiancheng State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China School of Electrical Engineering Automation Harbin Institute of Technology Harbin China

ISBN: (纸本)9781728137261

In the competition of 'RoboMaster', the robot, a mobile platform with a two-axis pan-tilt and a barrel, needs to shoot the target by launching a projectile. In order to detect and shoot the target automatically, we develop a visual system with a monocular camera mounted on the chassis. Based on some target detection algorithms, the target's 3D pose in the camera coordinate system is obtained. As the launching mechanism of the robot is on the two-axis pan-tilt, it demands to further obtain target's pose in the pan-tilt coordinate system to achieve precise shooting. Therefore, how to obtain the relative position between the camera coordinate system and the pan-tilt coordinate system is the main problem in our research. We propose a fast and effective method for the relative position calibration between the camera and two-axis pan-tilt based on specular reflection. We utilize a plane mirror to reflect the laser pointer light path mounted on the barrel. Then, the camera calibration method is applied to obtain the rotation matrix between the camera coordinate system and the world coordinate system. We finally verify the effectiveness of our method through experiments and achieve the first place in the competition. © 2019 IEEE.

关键词： Calibration

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Hybrid-Driven Origami Gripper with Variable Stiffness and Finger Length

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Cyborg and Bionic systems 2024年第1期5卷 566-577页

作者： Zhuang Zhang Weicheng Fan Yongzhou Long Jiabei Dai Junjie Luo Shujie Tang Qiujie Lu Xinran Wang Hao Wang Genliang Chen State Key Laboratory of Mechanical System and Vibration and Shanghai Key Laboratory of Digital Manufacture for Thin-Walled StructuresShanghai Jiao Tong UniversityShanghai200240China School of Engineering Westlake UniversityHangzhouZhejiang310030China Academy for Engineering and Technology Fudan University200433ShanghaiChina Reds Lab Dyson School of Design EngineeringImperial College LondonLondonSW72DBU.K META Robotics Institute Shanghai Jiao Tong UniversityShanghai200240China

Soft grippers due to their highly compliant material and self-adaptive structures attract more attention to safe and versatile grasping tasks compared to traditional rigid ***,those flexible characteristics limit the strength and the manipulation capacity of soft *** this paper,we introduce a hybrid-driven gripper design utilizing origami finger structures,to offer adjustable finger stiffness and variable grasping *** gripper is actuated via pneumatic and cables,which allows the origami structure to be controlled precisely for contraction and extension,thus achieving different finger lengths and stiffness by adjusting the cable lengths and the input pressure.A kinematic model of the origami finger is further developed,enabling precise control of its bending angle for effective grasping of diverse objects and facilitating in-hand *** proposed design method enriches the field of soft grippers,offering a simple yet effective approach to achieve safe,powerful,and highly adaptive grasping and in-hand manipulation capabilities.

关键词： soft grippersin variable stiffness origami gripper origami finger structuresto adjustable finger stiffness pneumatic cableswhich finger length hybrid driven

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Fiber Bragg Grating-Based Sensor system for Sensing the Shape of Flexible Needles

SSRN

引用

SSRN 2022年

作者： Zhang, Leifeng Li, Changle Dong, Huijuan Liu, Xiaojing Sun, Tong Grattan, Kenneth T.V. Zhao, Jie State Key Laboratory of Robotics and Systems Harbin Institute of Technology Harbin150001 China Department of Oral and Maxillofacial Surgery Peking University School and Hospital of Stomatology National Engineering Laboratory for Digital and Material Technology of Stomatology Beijing Key Laboratory of Digital Stomatology Beijing100034 China School of Engineering & Technology City University of London Northampton Square LondonEC1V 0HB United Kingdom

Shape sensing is of importance for the manipulation of flexible needles. In this work, a 0.6 mm diameter stylet with five Fiber Bragg Gratings (FBGs) installed as triplets was designed. A novel model of local curvature is established. A gradient-based optimization method has been integrated into the complete algorithm for shape sensing and this is used to reduce the difference between the midpoint curvature and the mean curvature. The experimental results obtained show that the mean tip errors are 0.35mm, 0.30mm, 0.38mm in the single-bending, double-bending and space-bending experiments, respectively. In a torsion test experiment which was performed, when the rotation angle of the tip was less than 25°, the error seen was less than 0.5mm. Further, when the needle designed in this work was used to puncture a 60mm thickness, ex vivo biological tissue, the mean error of the measurement of the needle tip was 0.39mm. © 2022, The Authors. All rights reserved.

关键词： Fiber Bragg gratings

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