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Photostriction effect and electric properties of La-doped PMN-PT transparent ferroelectric ceramics

International Journal of Smart and Nano Materials 2024年第2期15卷 296-311页

作者： Zhiqiang Song Zhuo Zhang Yirong Yu Dabin Lin Department of Automation and Robotics Engineering School of AutomationWuxi UniversityWuxiChina School of Optoelectronic Engineering Xian Technological UniversityXi'anChina

Ferroelectric ceramics display a remarkable photostriction effect,which could facilitate the prevention of electromagnetic interference and promote the integration and miniaturization of actuator systems,indicating potential applications in glim-mer *** this work,highly transparent La-doped 0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3(0.9PMN-0.1PT)ceramicswere synthesized using a solid-state reaction method in an oxyge-nated *** and SEM were used to analyze the phase structure of the dense samples,which displayed a pure perovskite structure,with no trace of a pyrochlore *** La doping,the phase transitiontemperature shows a decreasing trend,and its dielectric constant could reach up to 20,*** P-E loop of the samples was gradually refined into a straight line with an increase in the doping *** La doping,the transparency of the 0.9PMN-0.1PT cera-mics was significantly enhanced and reached up to 61%at the near-infrared ***,the photogenerated voltage and deformation of the La-doped 0.9PMN-0.1PT ceramics were investigated under ultraviolet light of various *** 20 s of irradiation at an intensity of 800 mW/cm²,the max-imum voltage and deformation,with values of 40 V and 250 nm,respectively,were both found in the 1%La-doped 0.9PMN-0.1PT ceramics.

关键词： Photostriction ferroelectric Raman piezoelectric

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Cooperative output regulation of heterogeneous directed multi-agent systems:a fully distributed model-free reinforcement learning framework

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Science China(Information Sciences) 2025年第2期68卷 170-185页

作者： Xiongtao SHI Yanjie LI Chenglong DU Huiping LI Chaoyang CHEN Weihua GUI Guangdong Key Laboratory of Intelligent Morphing Mechanisms and Adaptive Robotics School of Mechanical Engineering and AutomationHarbin Institute of Technology (Shenzhen) School of Automation Central South University School of Marine Science and Technology Northwestern Polytechnical University School of Information and Electrical Engineering Hunan University of Science and Technology

In this paper, the cooperative output regulation(COR) problem of a class of unknown heterogeneous multi-agent systems(MASs) with directed graphs is studied via a model-free reinforcement learning(RL) based fully distributed eventtriggered control(ETC) strategy. First, we consider the scenario that the exosystem is accessible globally to all agents, an internal model-based augmented algebraic Riccati equation(AARE) is constructed, and its solution is learned by the proposed model-free RL algorithm via online input-output data. Further, for the scenario that the exosystem is accessible only to its adjacent followers, the distributed observers are designed for each agent to get the state of the exosystem, and an internal modelbased fully distributed adaptive ETC protocol is then synthesized to construct the corresponding AARE, and the feedback gain matrix is learned in a model-free fashion. The model-free RL-based control protocol proposed in this paper can not only remove the prior knowledge of agents' dynamics, but also release the dependence on global information by the adaptive event-triggered mechanism(ETM) and the new graph-based Lyapunov function. Finally, simulation results are illustrated to show the feasibility and effectiveness of the proposed control scheme.

关键词： model-free reinforcement learning unknown heterogeneous multi-agent systems fully distributed event-triggered control directed graph

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Teleoperation with automatic posture regulation and broad learning control for assembly tasks

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Science China(Information Sciences) 2024年第11期67卷 359-360页

作者： Liwen SITU Zhenyu LU Chenguang YANG School of Automation Science and Engineering South China University of Technology Bristol Robotics Laboratory University of the West of England

In recent years, robot teleoperation systems have been widely used in assembly tasks due to their ability to combine human control with robotic execution, addressing limitations in precision, perception, and intelligence faced by fully automated robots. However, robot teleoperation for assembly tasks still encounters several challenges. In complex and unstructured environments, telerobots must regulate the posture of their manipulators to avoid obstacles and singularities, ensuring the safety of human operators [1].

关键词： Remote control

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A trajectory-level robot skill learning method based on fuzzy systems

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Science China(Information Sciences) 2025年第5期68卷 38-52页

作者： Chao ZENG Zhen DENG Boyang TI Yongsheng GAO Department of Computer Science University of Liverpool School of Mechanical Engineering and Automation Fuzhou University State Key Laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Sciences Institutes for Robotics and Intelligent Manufacturing Chinese Academy of Sciences State Key Laboratory of Robotics and System Harbin Institute of Technology

Learning from demonstration(LfD) allows for the effective transfer of human manipulation skills to a robot by building a model that represents these skills based on a limited number of demonstrated ***,a skilllearning model that can comprehensively satisfy multiple requirements,such as computational complexity,modeling accuracy,trajectory smoothness,and robustness,is still ***,this work aims to provide such a model by employing fuzzy ***,we introduce an LfD model named Takagi-Sugeno-Kang fuzzy system-based movement primitives(TSKFMPs),which exploits the advantages of the fuzzy theory for effective robotic imitation learning of human *** work formulates the TSK fuzzy system and gradient descent(GD) as imitation learning models,leveraging recent advancements in GD-based optimization for fuzzy *** study takes a two-step strategy.(ⅰ) The input-output relationships of the model are established using TSK fuzzy systems based on demonstration *** this way,the skill is encoded by the model parameter in the latent space.(ⅱ) GD is used to optimize the model parameter to increase the modeling accuracy and trajectory *** further explain how learned trajectories are adapted to new task scenarios through local *** conduct multiple tests using an open dataset to validate our method,and the results demonstrate performance comparable with those of other ***,we implement it in a real-world case study.

关键词： robot skill learning movement primitives TSK fuzzy systems gradient descent robotics

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Theoretical Model Construction and Static Performance Analysis of Multi-Leaf Journal Foil Bearings

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Journal of Tribology 2025年第7期147卷 074101页

作者： Hu, Yang Ding, Pengjing School of Mechatronic Engineering and Automation Shanghai Key Laboratory of Intelligent Manufacturing and Robotics Shanghai University Shanghai200072 China

Multi-leaf journal foil bearing (MLJFB) structures are complex, making performance prediction challenging, and the accurate prediction of gas film thickness and pressure distributions is crucial. In this study, comsol finite-element software was used to establish an initial foil assembly and structural deformation simulation model for an MLJFB with bump foils. Using matlab, a compressible gas lubrication model was established and solved using the finite volume method. Real-time data transfer between comsol and matlab enabled a fully coupled fluid-structure interaction simulation. This model meticulously accounts for the pre-tension force in the multi-leaf bearing assembly, contact friction between adjacent foils, and the interaction between the top foil and gas film pressure. The effects of journal movement distance, direction, and top foil overlapping ratio on the bearing capacity as well as the effects of different external load directions on the journal equilibrium position were analyzed based on this model. The results indicate that increasing the top foil overlapping ratio enhances the bearing capacity of the MLJFB. Furthermore, compared to the direction of the top foil overlap position, external loads applied in the direction of the top foil midpoint are more beneficial for bearing operational stability. Copyright © 2024 by ASME.

关键词： MATLAB

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Construction and manipulation of origami-inspired tubular structures with controlled mechanical buckling for collection and transportation of microspheres based on optically induced electrokinetics

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Science China(Technological Sciences) 2024年第9期67卷 2954-2964页

作者： YANG WenGuang WANG WenHao TENG XiangYu QIAO ZeZheng YU HaiBo School of Electromechanical and Automotive Engineering Yantai UniversityYantai 264005China State Key Laboratory of Robotics Shenyang Institute of AutomationChinese Academy of SciencesShenyang 110016China

The development of microengineered hydrogels has opened up unlimited possibilities for designing complex structures at the microscale. In this study, we constructed an origami-inspired tubular structure with controlled mechanical buckling based on optically induced electrokinetics(OEK). By inducing a stress gradient in the thickness, a tubular structure can be formed from a poly(ethylene glycol) diacrylate(PEGDA) hydrogel film of various shapes that have been custom fabricated. To achieve an ideal three-dimensional(3D) structure, the amplitude of the tubular structure can be controlled by adjusting the aspect ratios or polymerization time. Furthermore, the tubular structure can be manipulated for the collection and transportation of *** summary, we provide an effective method for designing 3D structures at the micro-nano scale. This forming method holds great potential for achieving various functions in tissue engineering, drug packaging, and transportation in the future.

关键词： origami-inspired tubular structures optically induced electrokinetics microfabrication mechanical buckling

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Vision-based docking system for an aromatic-hydrocarbon-inspired reconfigurable robot

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Science China(Technological Sciences) 2024年第6期67卷 1798-1816页

作者： XING FangYi XU Cheng LIU JinGuo XUE ZhiHui State Key Laboratory of Robotics Shenyang Institute of AutomationChinese Academy of SciencesShenyang110016China School of Automation and Electrical Engineering Shenyang Ligong UniversityShenyang110158China Institutes for Robotics and Intelligent Manufacturing Chinese Academy of SciencesShenyang110169China University of Chinese Academy of Sciences Beijing100049China

Aromatic hydrocarbons generally refer to compounds containing benzene *** types of isomers can be formed by replacing hydrogen atoms on the benzene *** this paper,an aromatic-hydrocarbon-inspired modular robot(AHIMR)is *** robot can be reassembled into different configurations suitable for various task requirements.A vision-based docking system is designed for the *** system primarily consists of two stages:a remote guidance stage and a precise docking *** the remote guidance stage,an object module is identified using an illumination adaptive target recognition algorithm,and then the active module moves to the docking area through communication with *** the precise docking stage,the active module calculates the relative pose with the object module using a perspective-n-point method and dynamically adjusts its posture to *** this process,a Kalman filter is used to reduce target occlusion and jitter *** addition,the docking system feasibility is verified via several simulation *** module docking accuracy is controlled within 0.01 m,which meets the reconfiguration task requirements of the *** the AHIMR submodule docking experiment,the active module accurately moves to the expected position with a docking success rate of 95%.

关键词： modular robot reconfiguration aromatic hydrocarbon autonomous docking visual identification

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Contact Force Estimation by Fusing Current and Tactile Information Through KF for Robot Arm

Contact Force Estimation by Fusing Current and Tactile Infor...

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2024 IEEE International Conference on robotics and Biomimetics, ROBIO 2024

作者： Tian, Yujie Guang, Chengfang Luo, Ruiqing Bao, Sheng Yuan, Jianjun Du, Liang Hu, Zhengtao School of Mechatronic Engineering and Automation Shanghai University Shanghai Key Laboratory of Intelligent Manufacturing and Robotics Shanghai China Shanghai Robotics Institute School of Mechatronic Engineering and Automation Shanghai University Shanghai China

ISBN: (纸本)9781665481090

Accurate contact force estimation is crucial for interactions between the robot arm and its environment. Presently, contact force estimation based on current information often suffers from biases caused by unmodeled errors, noise, and various other factors. In contrast, tactile sensors information effectively complements current information, enhancing the estimation of contact forces in robot arm interactions. To improve the accuracy of force estimation without force/torque sensors, we propose an information fusion method utilizing Kalman Filter (KF) to incorporate motor current with the tactile sensor for a nursing robot arm with Differential Modular Joints (DMJ). The coupling dynamic model of the DMJ and the contact force estimation model of the tactile sensor are established respectively. Subsequently, a linear KF fusion method is introduced based on these two methods. The experimental results indicate that contact force can be reliably estimated without force/torque sensors, significantly enhancing the accuracy of force estimation. © 2024 IEEE.

关键词： Robotic arms

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JADFER: Exploring Spatial-Contextual Interaction with Joint Attention Dropping for Facial Expression Recognition

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IEEE Transactions on Affective Computing 2024年第02期16卷 655-668页

作者： Gao, Yu Ren, Weihong Jiang, Weibo Dong, Qian Nie, Wei Wu, Wenhao Liu, Honghai Harbin Institute of Technology State Key Lab of Robotics and Systems School of Mechanical Engineering and Automation Harbin Institute of Technology Shenzhen518055 China

Facial Expression Recognition (FER) aims to categorize emotional expressions depicted on a human face, and is a challenging task under unconstrained conditions, such as face occlusions and pose variations. Recent methods usually adopt self attention or cross attention to explore global or local relationships among different level features. However, these methods are inclined to focus on the redundant facial regions, causing model overfitting. To address this problem, we propose a new FER model named JADFER, which drops the joint attention in the weight matrix to adaptively enhance facial expression representations. Specifically, our JADFER model consists of three components: Spatial Branch (SB), Contextual Branch (CB), and Spatial-Contextual Interaction (SCI). Firstly, SB runs N paths in parallel, where a Variety loss is designed to guide the paths of SB to focus on different discriminative regions. Meanwhile, CB abstracts the contextual facial representations using self attention with Joint Attention Dropping (JAD). Then, the SCI adopts the spatial features from SB to query the contextual representations from CB through cross attention with JAD, which regulates the attention weights by dropping the similar activations to further enhance the facial embeddings. Experimental results demonstrate that the proposed model outperforms the state-of-the-art methods on several FER benchmarks. © 2010-2012 IEEE.

关键词： Face recognition

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An Untethered Miniature Soft Jumping Robot Inspired by Quadrupeds

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Journal of Bionic engineering 2023年第4期20卷 1467-1480页

作者： Tianliang Zhong Fanan Wei Zhushan Zhai Wenguang Yang School of Mechanical Engineering and Automation Fuzhou UniversityFuzhou350108China School of Electromechanical and Automotive Engineering Yantai UniversityYantai264005ShandongChina State Key Laboratory of Robotics Shenyang Institute of AutomationChinese Academy of SciencesShenyang110016LiaoningChina

In recent years,designing a soft robot that can jump continuously and quickly explore in a narrow space has been a hot research *** the continuous efforts of researchers,many types of actuators have been developed and successfully employed to actuate the rapid locomotion of soft *** these mechanisms have enabled soft robots with excellent movement capabilities,they largely rely on external energy supply cables,which greatly limits their ***,it is still a big challenge to realize the unconstrained movement of the soft robot and the flexible adjustment of the movement direction in a narrow ***,a wireless magnetically controlled soft jumping robot with single-leg is proposed,which can achieve continuous and rapid jumping ***'s more interesting is that by changing the frequency and waveform of the control signal,this soft robot can easily switch between forward and backward *** motion direction switching function enables the magnetically controlled soft robot to return to the initial position without adjusting the direction when it completes the operation in a narrow pipe or takes the wrong path,which greatly improves the motion efficiency of the soft jumping robot and broadens its application field.

关键词： Wireless Magnetically controlled Soft robot Jumping Bidirectional motion

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