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15th IEEE International Conference on Mechatronics and Automation, ICMA 2018

作者： Liu, Dongyu Liu, Hong He, Yu Zhang, Bainan Liu, Yechao Li, Zhiqi Luo, Chao State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin Heilongjiang Province China Institute of Manned Spacecraft System Engineering China Academy of Space Technology Beijing China

ISBN: (纸本)9781538660720

In order to verify the flexible joint friction model with harmonic drive, the method of on orbit identification and the effect of joint friction on joint control, Chinese Space laboratory Tiangong - 2 equipped with a Space Manipulator and Dexterous Hand system (SMDHS). Manipulator joint friction identification experiment was carried out on orbit. In this paper, a flexible joint model of manipulator is established. By using the experimental data obtained on orbit, the friction model of viscous friction plus coulomb friction, the cubic polynomial friction model and the Stribeck friction model are compared and analyzed. At the same time, the effect of gravity difference on joint friction is also analyzed. The on orbit experiment prove that the quasi-linear model of viscous friction plus coulomb friction can be used to predict the friction of unrecognized velocity range, the accuracy of joint position control can also tolerate the error of this quasi-linear friction model in engineering applications. The flexible joint model and on orbit identification method established in this paper are helpful to develop the follow up large scale space manipulator and recognize the joint friction characteristics more clearly in the orbital application, so as to further improve the fine operating performance of the manipulator. © 2018 IEEE.

关键词： Friction

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Active Disturbance Rejection Control for a Multiple-Flexible-Link Manipulator

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Journal of Harbin Institute of Technology(New Series) 2018年第1期25卷 18-28页

作者： Yanfang Liu Hong Liu Yao Meng State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 China Department of Aerospace Engineering Harbin Institute of TechnologyHarbin 150001 China Aerospace System Engineering Shanghai Shanghai 201109 China

The control problem of multiple-flexible-link manipulators( MFLMs) is studied in this *** dynamic model of MFLM is derived and separated into two-time scale by utilizing the singular perturbation technique. The active disturbance rejection control( ADRC) is adopted to the slow subsystem to track a desired trajectory. The proposed ADRC structure preshapes the desired trajectory by utilizing the tracking differentiator,estimates the disturbance and internal states with an extended state observer,and guarantees a robust performance by combining a feedback controller with a feedforward term. Two types of feedback controllers are designed,proportional derivative( PD) controller and nonlinear PD( NPD) controller. For the fast subsystem,a fast stabilizing control is designed according to the standard linear quadratic regulator approach. Simulations are performed to evaluate the proposed control *** show that,compared with the traditional PD controller,the ADRC structure based control scheme has smaller overshot and shorter settling time,suppresses vibration quickly,and is robust to the maneuver speed. In general,the control scheme utilizing ADRC structure and NPD feedback controller shows better performance.

关键词： multiple-flexible-link manipulator ( MFLM) active disturbance rejection control (ADRC) nonlinear proportional plus derivative ( NPD) tracking differentiator ( TD) extended state observer ( ESO)

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On diffusive non-reciprocity and thermal diode

arXiv

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arXiv 2019年

作者： Li, Ying Li, Jiaxin Qiu, Cheng-Wei Department of Electrical and Computer Engineering National University of Singapore Kent Ridge17583 Singapore State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China

Wave propagation and diffusion in linear materials preserve local reciprocity in terms of a symmetric Green's function. For wave propagations, people usually focus on the signals entering and leaving a system, and do not need detailed information about the fields inside it. In such cases, the global reciprocity of the scattering off a system through several ports is more important, which is defined as the symmetric transmission between the scattering channels. When a two-port system supports non-reciprocal (electromagnetic, acoustic) wave propagation, it is a (optical, phonon) diode directly following the definition. However, to date no clear definition or discussion has been made on the global reciprocity of diffusive processes through a system. It thus remains a question whether diffusive non-reciprocity is related with diode for diffusive fields, say, a thermal diode. Here, we provide theoretical analysis based on local reciprocity and define the global reciprocity of diffusion through a two-port system. We further prove the equivalence between a non-reciprocal heat transfer system and a thermal diode, and discuss some methods to realize it. Our results set a general background for future studies on symmetric and asymmetric diffusive processes. Copyright © 2019, The Authors. All rights reserved.

关键词： Acoustic wave propagation

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Feature-Based and Convolutional Neural Network Fusion Method for Visual Relocalization 15

Feature-Based and Convolutional Neural Network Fusion Method...

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15th International Conference on Control, Automation, robotics and Vision, ICARCV 2018

作者： Wang, Li Li, Ruifeng Sun, Jingwen Soon Seah, Hock Quah, Chee Kwang Zhao, Lijun Harbin Institute of Technology State Key Laboratory of Robotics and System Harbin China Nanyang Technological University Singapore Singapore Pte Ltd Singapore Singapore

ISBN: (纸本)9781538695821

Relocalization is one of the necessary modules for mobile robots in long-term autonomous movement in an environment. Currently, visual relocalization algorithms mainly include feature-based methods and CNN-based (Convolutional Neural Network) methods. Feature-based methods can achieve high localization accuracy in feature-rich scenes, but the error is quite large or it even fails in cases with motion blur, texture-less scene and changing view angle. CNN-based methods usually have better robustness but poor localization accuracy. For this reason, a visual relocalization algorithm that combines the advantages of the two methods is proposed in this paper. The BoVW (Bag of Visual Words) model is used to search for the most similar image in the training dataset. PnP (Perspective n Points) and RANSAC (Random Sample Consensus) are employed to estimate an initial pose. Then the number of inliers is utilized as a criterion whether the feature-based method or the CNN-based method is to be leveraged. Compared with a previous CNN-based method, PoseNet, the average position error is reduced by 45.6% and the average orientation error is reduced by 67.4% on Microsoft's 7-Scenes datasets, which verifies the effectiveness of the proposed algorithm. © 2018 IEEE.

关键词： Neural networks

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A Unified Active Assistance Control Framework of Hip Exoskeleton for Walking and Balance Assistance*

A Unified Active Assistance Control Framework of Hip Exoskel...

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2019 IEEE/RSJ International Conference on Intelligent Robots and systems (IROS)

作者： Shiyin Qiu Wei Guo Pengfei Wang Fei Chen Fusheng Zha Xin Wang Jing Deng State Key Laboratory of Robotics and System School of Mechatronics Engineering Harbin Institute of Technology Harbin China Department of Advanced Robotics Istituto Italiano di Tecnologia 30 Genova Italy Shenzhen Academy of Aerospace Technology Shenzhen China

To actively assist human walking and balance recovery, a unified active assistance control framework of the hip exoskeleton is proposed in this paper. At the beginning of this paper, the condition of active assistance is analyzed. And then, a novel virtual stiffness model is proposed based on the analysis of human hip joint torque during walking and balance recovery. The virtual stiffness model is utilized to generate the desired active assistance torque profile for active walking and balance assistance. Next, the unified active assistance control framework is established based on the virtual stiffness model. Finally, the effectiveness of the proposed control framework is demonstrated by walking experiments. The results of the forward walking experiment show that the muscle effort of iliopsoas is reduced and the amplitude of hip joint motion is enlarged with the assistance of hip exoskeleton. The walking forward pull experiments and the walking backward pull experiments show that when the human suffers from a forward or backward disturbance force during forward walking, exoskeleton can help human regain balance faster and can enlarge the margin of stability (MoS) of the human.

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Singularity Robust Path Planning for Real Time Base Attitude Adjustment of Free-floating Space Robot

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International Journal of Automation and computing 2017年第2期14卷 169-178页

作者： Cheng Zhou Ming-He Jin Ye-Chao Liu Ze Zhang Yu Liu Hong Liu State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 China

This paper presents a singularity robust path planning for space manipulator to achieve base （satellite） attitude adjustment and end-effector task. The base attitude adjustment by the movement of manipulator will save propellant compared with conventional attitude control system. A task-priority reaction null-space control method is applied to achieve the primary task of adjusting attitude and secondary task of accomplishing end-effector task. Furthermore, the algorithm singularity is eliminated in the proposed algorithm compared with conventional reaction null-space algorithm. And the singular value filtering decomposition is introduced to dispose the dynamic singularity, the unit quaternion is also introduced to overcome representation singularity. Hence, a singularity robust path planning algorithm of space robot for base attitude adjustment is derived. A real time simulation system of the space robot under Linux/RTAl （realtime application interface） is developed to verify and test the feasibility and reliability of the method. The experimental results demonstrate the feasibility of online base attitude adjustment of space robot by the proposed algorithm.

关键词： Space robot path planning base attitude adjustment task priority reaction null-space.

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Author Correction: Super-resolution multicolor fluorescence microscopy enabled by an apochromatic super-oscillatory lens with extended depth-of-focus

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Nature communications 2024年第1期15卷 1510页

作者： Wenli Li Pei He Dangyuan Lei Yulong Fan Yangtao Du Bo Gao Zhiqin Chu Longqiu Li Kaipeng Liu Chengxu An Weizheng Yuan Yiting Yu Ningbo Institute of Northwestern Polytechnical University College of Mechanical Engineering Northwestern Polytechnical University Xi'an 710072 China. Key Laboratory of Micro/Nano Systems for Aerospace (Ministry of Education) Northwestern Polytechnical University Xi'an 710072 China. Shaanxi Province Key Laboratory of Micro and Nano Electro-Mechanical Systems Northwestern Polytechnical University Xi'an 710072 China. Department of Materials Science and Engineering City University of Hong Kong Hong Kong 999077 China. dangylei@cityu.edu.hk. Department of Materials Science and Engineering City University of Hong Kong Hong Kong 999077 China. The Institute of AI and Robotics Fudan University Shanghai 200433 China. Key Laboratory of Spectral Imaging Technology of Chinese Academy of Sciences Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi'an 710119 China. Department of Electrical and Electronic Engineering Joint Appointment with School of Biomedical Sciences The University of Hong Kong Hong Kong 999077 China. State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin Heilongjiang 150001 China. Ningbo Institute of Northwestern Polytechnical University College of Mechanical Engineering Northwestern Polytechnical University Xi'an 710072 China. yyt@***. Key Laboratory of Micro/Nano Systems for Aerospace (Ministry of Education) Northwestern Polytechnical University Xi'an 710072 China. yyt@***. Shaanxi Province Key Laboratory of Micro and Nano Electro-Mechanical Systems Northwestern Polytechnical University Xi'an 710072 China. yyt@***.

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Reaction Torque Control of Redundant Free-floating Space Robot

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International Journal of Automation and computing 2017年第3期14卷 295-306页

作者： Ming-He Jin Cheng Zhou Ye-Chao Liu Zi-Qi Liu Hong Liu State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 China

This paper presents the reaction torque based satellite base reactionless control or base disturbance minimization of a redundant free-floating space robot. This subject is of vital importance in the study of the free-floating space robot because the base disturbance minimization will result in less energy consumption and prolonged control application. The analytical formulation of the reaction torque is derived in this article, and the reaction torque control can achieve reactionless control and satellite base disturbance minimization. Furthermore, we derive the reaction torque based control of the space robot for base disturbance minimization from both the non-strict task priority and strict task priority control strategy. The dynamics singularity in the proposed algorithm is avoided in this paper. Besides, a real time simulation system of the space robot under Linux/real time application interface（RTAI） is developed to verify and test the feasibility and reliability of the method. The experimental results demonstrate the feasibility of online reaction torque control of the redundant free-floating space robot.

关键词： Redundant space robot reaction torque reactionless control base disturbance minimization Linux/real time application interface（RTAI）

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A Discriminative Algorithm for Indoor Place Recognition Based on Clustering of Features and Images

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International Journal of Automation and computing 2017年第4期14卷 407-419页

作者： Ke Wang Xue-Xiong Long Rui-Feng Li Li-Jun Zhao State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 China

In order to solve the problem of indoor place recognition for indoor service robot, a novel algorithm, clustering of features and images （CFI）, is proposed in this work. Different from traditional indoor place recognition methods which are based on kernels or bag of features, with large margin classifier, CFI proposed in this work is based on feature matching, image similarity and clustering of features and images. It establishes independent local feature clusters by feature cloud registration to represent each room, and defines image distance to describe the similarity between images or feature clusters, which determines the label of query images. Besides, it improves recognition speed by image scaling, with state inertia and hidden Markov model constraining the transition of the state to kill unreasonable wrong recognitions and achieves remarkable precision and speed. A series of experiments are conducted to test the algorithm based on standard databases, and it achieves recognition rate up to 97% and speed is over 30 fps, which is much superior to traditional methods. Its impressive precision and speed demonstrate the great discriminative power in the face of complicated environment.

关键词： Indoor place recognition locally and globally independent clustering of features and images （CFI） state inertia hidden Markov model.

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Fast feature matching based on r-nearest k-means searching

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CAAI Transactions on Intelligence Technology 2018年第4期3卷 198-207页

作者： Ke Wang Ningyu Zhu Yao Cheng Ruifeng Li Tianxiang Zhou Xuexiong Long State Key Laboratory of Robotics and System School of MechatronicsHarbin Institute of TechnologyHarbin 150001People’s Republic of China China Mobile (Hangzhou) Information Technology Co. LtdHangzhou 311100People’s Republic of China

Feature matching has been frequently applied in computer vision and pattern *** this paper,the authors propose a fast feature matching algorithm for vector-based *** algorithm searches r-nearest neighborhood clusters for the query point after a k-means clustering,which shows higher efficiency in three ***,it does not reformat the data into a complex tree,so it shortens the construction time ***,their algorithm adopts the r-nearest searching strategy to increase the probability to contain the exact nearest neighbor(NN)and take this NN as the global one,which can accelerate the searching speed by 170 ***,they set up a matching rule with a variant distance threshold to eliminate wrong *** algorithm has been tested on large SIFT databases with different scales and compared with two widely applied algorithms,priority search km-tree and random *** results show that their algorithm outperforms both algorithms in terms of speed up over linear search,and consumes less time than ***,they carry out the CFI test based on ISKLRS database using their *** test results show that their algorithm can greatly improve the recognition speed without affecting the recognition rate.

关键词： Feature matching

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