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Learning to Identify Footholds from Geometric Characteristics for a Six-legged Robot over Rugged Terrain

Journal of Bionic Engineering 2020年第3期17卷 512-522页

作者： Jie Chen Chong Liu Haibin Zhao Yanhe Zhu Jie Zhao School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China

Foothold identification is a key ability for legged robots that allows generating terrain adaptive behaviors(e.g.,gait and control parameters)and thereby improving mobility in complex *** this end,this paper addresses the issue of foothold characterization and identification over rugged terrain,from the terrain geometry point of *** a terrain region that might be a potential foothold of a robotic leg,the characteristic features are extracted as two first-order partial derivatives and two curvature parameters of a quadric regression surface at this *** features are able to give an intuitive and,more importantly,accurate characterization towards the specific geometry of the ground *** this basis,a supervised learning technique,Support Vector Machine(SVM),is employed,seeking to Ieam a foothold identification policy from human expert *** a result,an SVM classifier is leamt using the extracted features and human-demonstrated labels,which is able to identify whether or not a certain ground location is suited as a safe foot support for a robotic *** is shown that over 90%identification rate can be achieved with the proposed ***,preliminary experiment is implemented with a six-legged robot to demonstrate the effectiveness of the proposed approach.

关键词： six-legged robot foothold characterization foothold identification geometric characteristics support vector machine

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Reliability Design of Manipulator Joint for China Space Station 2

Reliability Design of Manipulator Joint for China Space Stat...

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2nd International Conference on Artificial Intelligence, Automation, and High-Performance Computing, AIAHPC 2022

作者： Li, Delun Zhu, Chao Zhang, Yun Bai, Mei Huang, Zhipeng Xie, Zongwu Liu, Teng Fu, Hao State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China Beijing Key Laboratory of Intelligent Space Robotic Systems Technology and Applications Beijing Institute of Spacecraft System Engineering CAST Beijing100094 China Beijing Satellite Manufacturing Co. Ltd. Beijing100094 China Beijing Institute of Space Environment Engineering Beijing100094 China

ISBN: (纸本)9781510657717

The TianHe manipulator is responsible for major tasks such as China Space Station construction, operation, and supporting astronaut's extravehicular operations. The joint is the direct execution part of the manipulator to realize flexible movement, and it is the key component to ensure the core functions and performance of the China Space Station manipulator, The composition of the joint is complex, and the experience of its reliability design is very poor. So the research of reliability design method for the joint is of great significance. Starting from the joint reliability design method, this paper uses various methods such as redundant design, margin design, and environmental adaptability design to complete the joint reliability design comprehensively. The ideas and methods for reliability design for the joint of the China Space Station manipulator introduced in this paper have important reference value for the reliability design for the space complicated electromechanical products. © 2022 SPIE. All rights reserved.

关键词： Space stations

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A Combined Inverse Kinematics Algorithm Using FABRIK with Optimization

arXiv

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arXiv 2022年

作者： Xu, Zichun Li, Yuntao Yang, Xiaohang Zhao, Zhiyuan Zhao, Jingdong Liu, Hong The State Key Laboratory of Robotics and System Harbin Institute of Technology Heilongjiang Province Harbin150001 China

Forward and backward reaching inverse kinematics (FABRIK) is a heuristic inverse kinematics solver that is gradually applied to manipulators with the advantages of fast convergence and generating more realistic configurations. However, under the high error constraint, FABRIK exhibits unstable convergence behavior, which is unsatisfactory for the real-time motion planning of manipulators. In this paper, a novel inverse kinematics algorithm that combines FABRIK and the sequential quadratic programming (SQP) algorithm is presented, in which the joint angles deduced by FABRIK will be taken as the initial seed of the SQP algorithm to avoid getting stuck in local minima. The combined algorithm is evaluated with experiments, in which our algorithm can achieve higher success rates and faster solution times than FABRIK under the high error constraint. Furthermore, the combined algorithm can generate continuous trajectories for the UR5 and KUKA LBR IIWA 14 R820 manipulators in path tracking with no pose error and permitted position error of the end-effector. Copyright © 2022, The Authors. All rights reserved.

关键词： Inverse kinematics

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A novel design of force-feedback master manipulator for remote ultrasound scanning

A novel design of force-feedback master manipulator for remo...

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IEEE International Conference on robotics and Biomimetics

作者： ChangLe Li ChenTao Zhang Chuan You Yu LeiFeng Zhang GangFeng Liu Jie Zhao State Key Laboratory of Robotics and System Harbin Institute of Technology HeiLongJiang China

ISBN: (纸本)9781665481106

This paper presents a novel six-degree-of-freedom force feedback master manipulator for remote ultrasound scanning. Firstly, a new configuration based on a planar five-link mechanism is proposed, taking into account the practical needs of medical ultrasound scanning. This configuration has two operating modes and can provide three degrees of force feedback. Secondly, a hybrid force/position master-slave control system based on the kinetic model force feedback method is built, which can realize incremental master-slave control, variable proportional control, force feedback, and other functions. Finally, the positional accuracy, gravity balance effect, and force feedback performance of this master manipulator are verified through experiments. Experiments show that the average position error of this novel force feedback master manipulator is 1.18 mm, the average attitude error expressed in terms of Euler angles is 0.83°, and the maximum feedback force that can be provided is 12.1 N, which satisfies the requirements of ultrasonic scanning.

关键词： Ultrasonic imaging Tracking Proportional control Machine vision Force feedback Manipulators Main-secondary

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Permanent Magnet Shape Optimization Method for PMSM Air Gap Flux Density Harmonics Reduction

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CES Transactions on Electrical Machines and systems 2021年第4期5卷 284-290页

作者： Chengsi Liu Yongxiang Xu Jibin Zou Guodong Yu Liang Zhuo School of Electrical Engineering and Automation of HIT Department of Electrical Engineering Harbin Institute of Technology the State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin Institute of Technology and National Engineering Research Center for Small and Special Precision Motors Guizhou Aerospace Linquan Motor Co.Ltd

This paper proposed a permanent magnet optimization method to suppress the air gap flux density harmonic of permanent magnet synchronous motor(PMSM).The method corrected the effective air gap length of the motor,calculated the magnetization length of the permanent in the case of parallel magnetization,and took the influence of the permanent magnet relative permeability into *** on these works,for a given sinusoidal air gap flux density waveform,the corresponding structural parameters can be calculated,so as to achieve the optimization of the permanent *** using this method to optimize the shape of the magnet,the fundamental wave of the air gap flux density can be retained to the greatest extent,so as to eliminate harmonics and maintain the output capacity at the same *** feasibility and accuracy of the method have been verified by finite element analysis(FEA)and prototype machine *** method is simple and time-saving,and has a satisfactory accuracy,which provides a reference method for permanent magnet optimization of PMSM.

关键词： Permanent magnet synchronous motor(PMSM) analytical method finite element analysis(FEA) magnet shape optimization.

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FlexDelta: A flexure-based fully decoupled parallel xyz positioning stage with long stroke

arXiv

引用

arXiv 2023年

作者： Zhang, Qianjun Dong, Wei Xu, Qingsong Goteea, Bimal J. Gao, Yongzhuo State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150000 China Department of Electromechanical Engineering Faculty of Science and Technology University of Macau Macau999078 China

Decoupled parallel xyz positioning stages with large stroke have been desired in high-speed and precise positioning fields. However, currently such stages are either short in stroke or unqualified in parasitic motion and coupling rate. This paper proposes a novel flexure-based decoupled parallel xyz positioning stage (FlexDelta) and conducts its conceptual design, modeling, and experimental study. Firstly, the working principle of FlexDelta is introduced, followed by its mechanism design with flexure. Secondly, the stiffness model of flexure is established via matrix-based Castigliano’s second theorem, and the influence of its lateral stiffness on the stiffness model of FlexDelta is comprehensively investigated and then optimally designed. Finally, experimental study was carried out based on the prototype fabricated. The results reveal that the positioning stage features centimeter-stroke in three axes, with coupling rate less than 0.53%, parasitic motion less than 1.72 mrad over full range. And its natural frequencies are 20.8 Hz, 20.8 Hz, and 22.4 Hz for x, y, and z axis respectively. Multi-axis path tracking tests were also carried out, which validates its dynamic performance with micrometer error. Copyright © 2023, The Authors. All rights reserved.

关键词： Stiffness

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Tunable Rectification of Diffusion-Wave Fields by Spatiotemporal Metamaterials

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Physical Review Letters 2022年第25期129卷 256601-256601页

作者： Jiaxin Li Zhanxiang Zhang Guoqiang Xu Haoran Sun Lizhou Dai Tianlong Li Cheng-Wei Qiu Department of Electrical and Computer Engineering National University of Singapore Singapore 117583 Singapore State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 China

The diffusion process is the basis of many branches of science and engineering, and generally obeys reciprocity between two ports of a linear time-invariant medium. Recent research on classical wave dynamics has explored the spatiotemporal modulation to exhibit preferred directions in photons and plasmons. Here we report a distinct rectification effect on diffusion-wave fields by modulating the conductivity and observe nonreciprocal transport of charges. We experimentally create a spatiotemporal diffusion metamaterial, in which a mode transition to zero frequency is realized. A direct current component thereby emerges, showcasing a biased effect on the charge diffusion when the incident fundamental frequency is a multiple of the system modulation frequency. These results may find applications spanning a plethora of diffusive fields in general.

关键词： Diffusion Metamaterials Bloch-Floquet theorem

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Comprehensive Study of Plastic Deformation Mechanism of Polycrystalline Copper Using Crystal Plasticity Finite Element

SSRN

引用

SSRN 2024年

作者： Zhou, Xingying Zan, Shusong Zeng, Yifei Guo, Ruiyang Wang, Guangzhou Wang, Tingzhang Zhao, Linjie Chen, Mingjun State Key Laboratory of Robotics and System Harbin Institute of Technology Heilongjiang Harbin150001 China Machining and Condition Monitoring Group Faculty of Engineering University of Nottingham NG81BB United Kingdom

Graded polycrystalline copper materials have been expected in the field of scientific research and engineering in recent years because the core of the material has enough toughness and a sufficient surface strength. However, the plastic deformation mechanism, gradient grain generation mechanism and material strengthening principle of polycrystalline copper are still not well understood. Therefore, it is urgent to further analyze the plastic deformation of polycrystalline copper. In this study, the micron scale plastic deformation behavior of polycrystalline copper is simulated based on the crystal plasticity finite element method. The simulation analysis is carried out from the aspects of grain size, grain shape, crystal orientation type and quantity, loading mode and so on. The effects of the above parameters on the Mises stress nephogram and stress-strain curve of polycrystalline copper were analyzed. At the end of the article, the EBSD orientation distribution information of graded polycrystalline copper grains obtained in the cutting process is analyzed comprehensively and the formation mechanism of graded polycrystalline copper is explained by combining the simulation results. © 2024, The Authors. All rights reserved.

关键词： Crystal orientation

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Design and Experiment of A Hybrid Wave Energy Harvester Based on Tapered Rollers

Design and Experiment of A Hybrid Wave Energy Harvester Base...

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Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS)

作者： Yunfei Li Tianyi Tang Yan Fang Manjuan Huang Cheng Hou Huicong Liu Lining Sun State Key Laboratory of Robotics and System Harbin Institute of Technology (HIT) Harbin China School of Mechanical and Electric Engineering Jiangsu Provincial Key Laboratory of Advanced Robotics Soochow University CHINA State Key Laboratory of Robotics and System Harbin Institute of Technology (HIT) China

ISBN: (纸本)9781665493079

This paper presents a hybrid energy harvester based on tapered rollers with an electromagnetic generator (EMG) component and a triboelectric nanogenerator (TENG) component for ultra-low frequency wave energy harvesting. The chaotic pendulum is adjusted to adapt the wave excitation under different sea conditions, ensuring that the device achieves optimal output performance. At excitation frequency of 1Hz and the tilt angle of 60°, the open-circuit voltage peaks of 8.4 and 132 V can be achieved by the EMG and TENG, respectively, corresponding to the power outputs of 4.38 and 0.078 mW, respectively. It was demonstrated that the device can easily light up over 360 red light-emitting diodes.

关键词： Performance evaluation Oceans Voltage Energy conversion Light emitting diodes Electromyography Sensors

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Spatial Correspondence between Graph Neural Network-Segmented Images

arXiv

引用

arXiv 2023年

作者： Li, Qian Fu, Yunguan Yang, Qianye Du, Zhijiang Yu, Hongjian Hu, Yipeng Department of Medical Physics and Biomedical Engineering University College London London United Kingdom State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China

Graph neural networks (GNNs) have been proposed for medical image segmentation, by predicting anatomical structures represented by graphs of vertices and edges. One such type of graph is predefined with fixed size and connectivity to represent a reference of anatomical regions of interest, thus known as templates. This work explores the potentials in these GNNs with common topology for establishing spatial correspondence, implicitly maintained during segmenting two or more images. With an example application of registering local vertebral sub-regions found in CT images, our experimental results showed that the GNN-based segmentation is capable of accurate and reliable localization of the same interventionally interesting structures between images, not limited to the segmentation classes. The reported average target registration errors of 2.2±1.3 mm and 2.7±1.4 mm, for aligning holdout test images with a reference and for aligning two test images, respectively, were by a considerable margin lower than those from the tested non-learning and learning-based registration algorithms. Further ablation studies assess the contributions towards the registration performance, from individual components in the originally segmentation-purposed network and its training algorithm. The results highlight that the proposed segmentation-in-lieu-of-registration approach shares methodological similarities with existing registration methods, such as the use of displacement smoothness constraint and point distance minimization albeit on non-grid graphs, which interestingly yielded benefits for both segmentation and registration. We, therefore, conclude that the template-based GNN segmentation can effectively establish spatial correspondence in our application, without any other dedicated registration algorithms. © 2023, CC BY.

关键词： Computerized tomography

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