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

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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Networked Dielectric Elastomer Balloon Actuators with Large Deformation

Networked Dielectric Elastomer Balloon Actuators with Large ...

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IEEE International Conference on Cyber Technology in Automation, Control, and Intelligent systems

作者： Feifei Chen Kun Liu State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Robotics Institute School of Mechanical Engineering Shanghai Jiao Tong University Shanghai China

ISBN: (数字)9781728107707

ISBN: (纸本)9781728107714

Soft robots have recently received much interest because of their advantages over traditional rigid robots in terms of withstanding large deformations and interacting well with environments. Soft actuators, as a critical part of a soft robot, provide actuation force to generate desired motion. Dielectric elastomers have shown great promise because of their considerable voltage-induced deformation. Particularly, air-filled dielectric elastomer actuators have been well investigated, where the air inside provides prestretches to improve the actuation capability. This paper proposes a networked design of inflated dielectric elastomer actuators, capable of spanning a large actuation space and a corresponding large control space. Through comparing the performance of modulated operation mode and that of independent operation mode, we theoretically demonstrate that the networked design is able to, to a large extent, postpone the occurrence of material failures of the actuators, resulting in a large and continuous actuation range for their control.

关键词： Aerospace electronics Strain Dielectric elastomers Soft robotics Voltage control

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Buckling-induced Shape Morphing using Dielectric Elastomer Actuators Patterned with Spatially-varying Electrodes

Buckling-induced Shape Morphing using Dielectric Elastomer A...

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

作者： Feifei Chen Kun Liu Xiangyang Zhu State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University and Robotics Institute School of Mechanical Engineering Shanghai Jiao Tong University Shanghai China

Shape morphing is at the core of future research, which shows promise for wide applications ranging from reconfigurable electronics to soft material robots. In this paper, we present a novel buckling-induced mechanism for shape morphing using dielectric elastomer actuators (DEAs), by bonding the planar precursor structure's “feet” with the DEA. With spatially-varying electric fields applied, the inplane deformation of the DEA generates compressive loads to trigger buckling of planar precursors into desired three-dimensional configurations. To enlarge the achievable motion range at the “feet”, we develop a design optimization approach to the electrode arrangement which is concisely described by cosine functions. By numerically optimizing the cosine function coefficients, we obtain the optimal spatially-varying electrodes for various precursors with different patterns of bonding sites. The experimental results demonstrate the remarkable shape-morphing from two dimensions to three dimensional configurations. Our work paves the way to novel actuation mechanisms for shape-morphing structures, with advantages of rapid response and reversible controllability.

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Grip Force Perception Based on dAENN for Minimally Invasive Surgery Robot

Grip Force Perception Based on dAENN for Minimally Invasive ...

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IEEE International Conference on robotics and Biomimetics

作者： Yongchen Guo Bo Pan Yili Fu Max Q.-H. Meng State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin Heilongjiang China Department of Electronic Engineering Chinese University of Hong Kong Hong Kong China

Although robot assisted minimally invasive surgery brings the gospel to patients, force perception is gone. Among all the contact forces during surgery, the instrument grip force plays the most important role. In this paper, a grip force perception method based on denoising AutoEncoder Neural Network (dAENN) is proposed. The method utilizes sensor data including encoder readings and motor current over a time window as the input of dAENN for sufficient information. An Artificial Neural Network (ANN) is then introduced as a machine learning tool to learn the nonlinear mapping between the compact features and grip force labels. Feature extraction is first introduced into grip force perception problem in this paper. Experiment results shows adequate expressive capability of the extracted coding as well as the superior grip force perception performance over several popular data-based methods under the same dataset.

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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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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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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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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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