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Energy dissipation mechanism of annihilating reverse tilt domains for various applied voltages

Physical Review E 2024年第4期109卷 044703-044703页

作者： Takuya Yanagimachi National Institute of Technology Akita College School of Creative System Engineering Department of Mechanical Engineering and Robotics 1-1 Iijima Bunkyo-cho Akita 011-8511 Japan

When a voltage is applied to a uniformly aligned nematic liquid crystal, a characteristic texture designated as reverse tilt domain (RTD) appears. The RTD, surrounded by a domain wall, gradually shrinks and finally disappears. The domain wall splits into a pair of disclination lines by increase of the voltage. This work examines the energy dissipation mechanism of annihilation dynamics by ascertaining the phenomenological viscosity Γ based on experimentation. To evaluate Γ, the time dependence of curvature radius R is analyzed using an equation R=At0−t, where A is a fitting parameter. Parameter A decreased linearly with increasing applied voltage and suddenly became constant. Also, Γ was evaluated from A as a function of voltage. When the voltage reaches a critical value, Γ increased sharply to be one order of magnitude greater than that under low voltages. The critical voltage is consistent with the theoretically expected value at which the splitting of domain wall occurs. The transition of Γ is described clearly by localized deformation of the director field.

关键词： Confinement Distortions & defects Elastic deformation Elastic forces Electric field effects Emergence of patterns Lubricants Mechanical deformation

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Micro-IMU-Based Motion Tracking system for Virtual Training

Micro-IMU-Based Motion Tracking System for Virtual Training

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第三十四届中国控制会议

作者： Yang Zhang Yunfeng Fei Lin Xu Guangyi Sun Institute of Robotics and Automatic Information System Nankai University Tianjin Key Laboratory of Intelligent Robotics Engineering Design and Research Institute of the Second Artillery Corps.

ISBN: (纸本)9781467374439

This paper presents the development of a low cost wireless real-time inertial body tracking system for virtual training. The system is designed to provide highly accurate human body motion capture and interactive three-dimensional(3-D) avatar steering, by combining low cost MEMS inertial measurement units(IMUs), wireless body sensor network(BSN), and Unity 3D virtual reality game engine. First, several wearable MEMS IMU sensors are placed on user's body and limbs according to human skeletal action, and each sensor performs a 9 degrees of freedom(DOF) tracking at a high-speed update rate. Second, a Zigbee-based BSN is designed to support up to 20 MEMS IMU sensor nodes data transmission at 50 Hz sampling frequency. All collected sensors' data are loaded to a Matlab-based PC program by means of serial port. In order to accurately estimate the local orientation of each IMU sensor, an optimized gradient descent algorithm is implemented. The algorithm uses a quaternion representation, which allows accelerometer and magnetometer data to be fused to compute the gyroscope measurement error as a quaternion derivative. Finally, the estimated orientation data by fusion algorithm are imported to a virtual environment, consisting of the 3-D virtual skeletal representation and the virtual scene for specific training. Experimental results indicate that the system achieves < 1o static RMS error and <2o dynamic RMS error. The systems further expand the usability of low cost body tracking solution to virtual training in virtual environments.

关键词： micro inertial measurement unit(IMU) motion capture virtual training gradient descent algorithm wireless sensor network

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Stability Analysis and Performance Evaluation of Delayed Bilateral Telerobotic systems over a Lossy Communication Channel

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Journal of systems Science & Complexity 2021年第1期34卷 157-179页

作者： BAKHSHI Ali ALFI Alireza TALEBI Heidar Ali SOURATGAR Amir Aboulfazl YOUSEFI Mahdi Faculty of Electrical and Robotic Engineering Shahrood University of TechnologyShahrood 36199-95161Iran Power Plants Control Systems Technology Development Plan Department of monitoring and ControlNiroo Research InstituteTehran 14665-517Iran Real-Time and Robotics system Laboratory Faculty of Electrical EngineeringAmirkabir University of TechnologyHafez AvenueTehran 15914Iran Electrical and Computer Engineering Department The University of British Columbia2385East MallVan couverBC V6T 1Z4Canada

The focus of this paper is to address a novel control technique for stability and transparency analysis of bilateral telerobotic systems in the presence of data loss and time delay in the communication channel. Different control strategies have been reported to compensate the effects of time delay in the communication channel;however, most of them result in poor performance under data loss. First, a model for data loss is proposed using a finite series representation of a set of periodic continuous *** improve the performance and data reconstruction, a holder circuits is also introduced. The passivity of the overall system is provided via the wave variable technique based on the proposed model for the data loss. The stability analysis of the system is then derived using the Lyapunov theorem under the time delay and the data loss. Finally, experimental results are given to illustrate the capability of the proposed control technique.

关键词： Lossy channel passivity stability telerobotic transparency

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Closest Distance Searching by GPU-Based Massive Parallel Computation

Closest Distance Searching by GPU-Based Massive Parallel Com...

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

作者： Yunfeng Fei Yinhao Song Guangyi Sun Engineering Design and Research Institute of the Second Artillery Corps. Nankai University Institute of Robotics and Automatic Information System Tianjin Key Laboratory of Intelligent Robotics

ISBN: (纸本)9781479987313

A simulation system for real-time closest distance searching is developed using GPU-based massive parallel computation technology. The system can be used for minimum distance detection between two three-dimensional (3-D) objects in a virtual environment. First, two 3-D models are converted into vertex/mesh format;then, CUDA-based GPU parallel computation is performed for the nearest neighbor searching, in order to find the closest separation Euler-distance of two objects;at last, Unity3D game engine is used as a testing platform for visualization. Experimental results indicate that the system not only works for arbitrary complex objects (i.e., non-convex object), but also has good real-time capability and high accuracy. Compared with traditional brute force algorithm, our parallel searching is about 50 times faster.

关键词： Closest distance searching Parallel computation GPU Collision detection Virtual reality PARALLEL PROCESSING (COMPUTERS) virtual reality Nearest neighbor query Simulation systems GRAPPER PICK UP Graphics Processing Unit real-time capability Collision detection Collision avoidance

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Ground Contact Parameter Estimation Guided Gait Planning for Hexapod Robots

Ground Contact Parameter Estimation Guided Gait Planning for...

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IEEE International Conference on robotics and Biomimetics

作者： Guiyu Dong Ripeng Qin Liangliang Han Jiawei Chen Kun Xu Xilun Ding Robotics Institute School of Mechanical Engineering and Automation Beihang University Beijing China Institute of Aerospace System Engineering Shanghai Shanghai China

ISBN: (纸本)9781665481106

Environment sensing for legged robots can improve their mobility performance. A foot-ground contact model can be used to evaluate the properties of the robot's contact with the environment. A contact parameter estimator based on artificial neural networks was developed to guide the gait planning of a hexapod robot so that it can achieve higher mobility efficiency. This contact parameter estimator can use acceleration, velocity, and contact force data as inputs and output contact parameters. The estimator avoided using deformations as input which are difficult to measure. Meanwhile, the robot's cost of transport with different contact parameters is tested and recorded. Accordingly, the hexapod robot was guided to choose a better gait shape between cycloid and rectangular. The simulation proved that changes in the gait shape according to the contact parameters can reduce the hexapod's cost of transport.

关键词： Robot motion Costs Parameter estimation Shape Force Robot sensing systems Real-time systems

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Direction-of-Arrival and Range Estimation of Near-Field Sources Based on Subspace Fitting

Direction-of-Arrival and Range Estimation of Near-Field Sour...

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2021 China Automation Congress, CAC 2021

作者： Tong, Yingnan Zuo, Weiliang Xin, Jingmin Zheng, Nanning Sano, Akira Institute of Artificial Intelligence and Robotics Xi'an Jiaotong University Xi'an710049 China National Engineering Laboratory for Visual Information Processing and Applications Xi'an Jiaotong University Xi'an710049 China Department of System Design Engineering Keio University Yokohama223-8522 Japan

ISBN: (纸本)9781665426473

A new algorithm is proposed to address the problem of near-field source localization using weighted subspace fitting (WSF) in this paper. Through separating the two parameters of bearings and ranges, the two-dimensional parameter estimation problem is first transformed into one-dimensional parameter estimation problem. The specific method is to construct a Toeplitz-like correlation matrix by using the anti-diagonal elements of the near-field source signal covariance matrix. Then the subspace fitting algorithm of sparse recovery is used to estimate the direction of arrival (DOA). The estimated direction is substituted back to the original near-field source model. After that, the sparse recovery algorithm based on singular value decomposition can be used to calculate the estimated value of the ranges. Computer simulations verify the excellent performance of the algorithm. In addition, the algorithm has lower requirements for SNR and snapshots. © 2021 IEEE

关键词： Singular value decomposition

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Numerical and experimental estimation of stiffness performances for the humanoid robot WABIAN-RV

Numerical and experimental estimation of stiffness performan...

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2003 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM 2003

作者： Carbone, G. Lim, Hun-Ok Takanishi, A. Ceccarelli, M. Laboratory of Robotics and Mechatronics DiMSAT University of Cassino Via Di Biasio 43 CassinoFr03043 Italy Dept. of System Design Engineering Kanagawa Institute of Technology 1030 Shimoogino AtugiKanagawa243-0292 Japan Humanoid Robotics Institute Waseda University 3-4-1 Ookubo Shinjuku-kuTokyo169-8555 Japan

In this paper, basic models and a formulation are presented for the stiffness analysis of the humanoid robot WABIAN-RV. An evaluation of stiffness performances is carried out by numerically implementing the proposed f... 详细信息

ISBN: (纸本)0780377591

关键词： Anthropomorphic robots

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Design and Analysis of Underactuated Robotic Hands for Spacecraft Surface Attachment

Design and Analysis of Underactuated Robotic Hands for Space...

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IEEE International Conference on robotics and Biomimetics

作者： Yang Luo Chang Wang Longfei Huang Jingya Ma Kun Xu Xilun Ding Robotics Institute School of Mechanical Engineering and Automation Beihang University Beijing China Institute of Spacecraft System Engineering CAST Beijing China

ISBN: (纸本)9781665481106

Amid rapid development of space technology, it is necessary to carry out relevant operations in space to ensure long and stable in-orbit operation of spacecraft in complex space environment. The end effector of the space manipulator is the main tool which completes the operational targets, but at present, the end effector can only deal with cooperative targets rather than non-cooperative targets. In order to solve the related problems, this paper investigates the bio-inspired dry adhesion, mechanical attachment devices and underactuated robotic hands at home and abroad, analyzes the attachment principle and application scenarios. Based on the studies, a cable-driven two-finger underactuated robotic hand with mixed attachment mode is designed. In this paper, the flexible joints of manipulators are calculated theoretically and simulated, the static characteristics analyzed, and the integrated manufacturing of joints and knuckles is achieved. The layout of flexible substrate and adhesive pad is reasonably designed to enlarge the contact area between the adhesive pad and the target object. A gripping mechanism with certain flexibility is developed to smoothly grasp objects of different shapes. According to the characteristics of different surfaces, targeted attachment control schemes are designed, a principle prototype built, and the attachment ability of the prototype to various surfaces is verified through tests.

关键词： Space vehicles Shape Space technology Prototypes End effectors Surface roughness Manufacturing

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Cell Nanomechanics Based on Dielectric Elastomer Actuator Device

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Nano-Micro Letters 2019年第4期11卷 690-708页

作者： Zhichao Li Chao Gao Sisi Fan Jiang Zou Guoying Gu Mingdong Dong Jie Song Institute of Nano Biomedicine and Engineering Department of Instrument Science and EngineeringSchool of Electronic Information and Electrical EngineeringShanghai Jiao Tong UniversityShanghai 200240People’s Republic of China Shanghai Engineering Research Center of Advanced Dental Technology and Materials Shanghai Ninth People’s HospitalShanghai Jiao Tong UniversityShanghai 200240People’s Republic of China Robotics Institute School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240People’s Republic of China State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240People’s Republic of China Interdisciplinary Nanoscience Center(iNANO) Aarhus UniversityAarhus 8000Denmark

As a frontier of biology,mechanobiology plays an important role in tissue and biomedical *** is a common sense that mechanical cues under extracellular microenvironment affect a lot in regulating the behaviors of cells such as proliferation and gene expression,*** such an interdisciplinary field,engineering methods like the pneumatic and motor-driven devices have been employed for ***,such techniques usually rely on complex structures,which cost much but not so easy to *** elastomer actuators(DEAs)are well known as a kind of soft actuation technology,and their research prospect in biomechanical field is gradually concerned due to their properties just like large deformation(>100%)and fast response(<1 ms).In addition,DEAs are usually optically transparent and can be fabricated into small volume,which make them easy to cooperate with regular microscope to realize real-time dynamic imaging of *** paper first reviews the basic components,principle,and evaluation of DEAs and then overview some corresponding applications of DEAs for cellular mechanobiology *** also provide a comparison between DEA-based bioreactors and current custom-built devices and share some opinions about their potential applications in the future according to widely reported results via other methods.

关键词： Dielectric elastomer actuator Mechanical stimulus Bioreactor Mechanobiology

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Robustifying Dynamic Positioning of Crane Vessels for Heavy Lifting Operation

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IEEE/CAA Journal of Automatica Sinica 2021年第4期8卷 753-765页

作者： Jun Ye Spandan Roy Milinko Godjevac Vasso Reppa Simone Baldi Department of Maritime and Transport Technology Delft University of TechnologyDelft 2628 CDThe Netherlands Robotics Research Center International Institute of Information Technology HyderabadHyderabad-500032India Future Proof Shipping Delft 3013 ALThe Netherlands School of Mathematics and School of Cyber Science and Engineering Southeast UniversityNanjing 210096China the Delft Center for System and Control Delft University of TechnologyDelft 2600 AA

Construction crane vessels make use of dynamic positioning(DP)systems during the installation and removal of offshore structures to maintain the vessel’s *** have reported cases of instability of DP systems during offshore operation caused by uncertainties,such as mooring ***"robustification"for heavy lift operations,i.e.,handling such uncertainties systematically and with stability guarantees,is a long-standing challenge in DP design.A new DP method,composed by an observer and a controller,is proposed to address this challenge,with stability guarantees in the presence of *** test the proposed method on an integrated cranevessel simulation environment,where the integration of several subsystems(winch dynamics,crane forces,thruster dynamics,fuel injection system etc.)allow a realistic validation under a wide set of uncertainties.

关键词： Construction crane vessels dynamic positioning system offshore robust control uncertainty

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