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arXiv 2020年

作者： Liu, Zuxin Chen, Baiming Zhou, Hongyi Koushik, Guru Hebert, Martial Zhao, Ding Department of Mechanical Engineering Carnegie Mellon University United States School of Vehicle and Mobility Tsinghua University China Robotics Institute Carnegie Mellon University United States

Multi-agent navigation in dynamic environments is of great industrial value when deploying a large scale fleet of robot to real-world applications. This paper proposes a decentralized partially observable multi-agent path planning with evolutionary reinforcement learning (MAPPER) method to learn an effective local planning policy in mixed dynamic environments. Reinforcement learning-based methods usually suffer performance degradation on long-horizon tasks with goal-conditioned sparse rewards, so we decompose the long-range navigation task into many easier sub-tasks under the guidance of a global planner, which increases agents’ performance in large environments. Moreover, most existing multiagent planning approaches assume either perfect information of the surrounding environment or homogeneity of nearby dynamic agents, which may not hold in practice. Our approach models dynamic obstacles’ behavior with an image-based representation and trains a policy in mixed dynamic environments without homogeneity assumption. To ensure multi-agent training stability and performance, we propose an evolutionary training approach that can be easily scaled to large and complex environments. Experiments show that MAPPER is able to achieve higher success rates and more stable performance when exposed to a large number of non-cooperative dynamic obstacles compared with traditional reaction-based planner LRA* and the state-of-the-art learning-based method. Copyright © 2020, The Authors. All rights reserved.

关键词： Multi agent systems

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Hybrid Actuator Design for a Gait Augmentation Wearable

arXiv

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arXiv 2020年

作者： Wan, Fang Wang, Zheng Franchuk, Brooke Hu, Xinyao Sun, Zhenglong Song, Chaoyang Fang Wan is an independent WuhanHubei China Department of Mechanical and Aerospace Engineering Monash University VIC3800 Australia Department of Mechanical and Aerospace Engineering University of British Columbia Canada Institute of Human Factors and Ergonomics Shenzhen University ShenzhenGuangdong China Institute of Robotics and Intelligent Manufacturing Chinese University of Hong Kong Shenzhen China Department of Mechanical and Aerospace Engineering Monash University VIC3800 Australia

— We describe a fluidic actuator design that replaces the sealed chamber of a hydraulic cylinder using a soft actuator to provide compliant linear compression with a large force (≥100 N) at a low operation pressure (≤50 kPa) for lower-limb wearable. The external shells constrain the deformation of the soft actuator under fluidic pressurization. This enables us to use latex party balloons as a quick and cheap alternative for initial design investigation. We found that the forces exerted by the soft material deformation are well-captured by the rigid shells, removing the necessity of explicitly describing the mechanics of the soft material deformation and its interaction with the rigid structure. One can use the classical Force, Pressure and Area formula factored with an efficiency parameter to characterize the actuator performance. Furthermore, we proposed an engineering design of the hybrid actuator using a customized soft actuator placed inside a single shell cavity with an open end for compression force. Our results show that the proposed design can generate a very high force within a short stroke distance. At a low input pressure of 50 kPa, the exerted block force is approaching only about 3% less than the classical equation predicted. The actuator is fitted to a new gait augmentation design for correcting knee alignment, which is usually challenging for actuators made from the purely soft material. Copyright © 2020, The Authors. All rights reserved.

关键词： Wearable technology

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Evaluation of a Circumferential Extending Antagonist Actuator in a Soft Arm

Evaluation of a Circumferential Extending Antagonist Actuato...

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IEEE International Conference on Soft robotics (RoboSoft)

作者： Max Asselmeier Ross L. Hatton Yiğit Mengüç Gina Olson Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign Urbana IL USA Collaborative Robotics and Intelligent Systems Institute Oregon State University Corvallis OR USA

ISBN: (数字)9781728165707

ISBN: (纸本)9781728165714

This paper presents a novel circumferential pneumatic actuator to be used as an antagonist in soft bending arms. The design is based on a McKibben actuator, and the circular shape is inspired by octopus musculature. The performance of the presented actuator is evaluated through characterization of individual actuators, as well as experimental analysis of the actuator's effect on the behavior of an existing soft bending arm segment. A stack of 16 circumferential actuators is capable of producing a force of 37 N when pressurized to 32 kPa and deflected to -15% strain. When the actuators are integrated into a 75 mm diameter soft arm, the arm is able to successfully lift 600 g (285% of its own mass) to 54% of the arm's original height, which is 2.2 times the maximum load for the arm without antagonistic actuators. When the soft arm with antagonistic actuators lifted 250 g at 40 kPa, the segment returned to 101% of its original height, compared to 59% for the arm segment without antagonistic actuators. Compared to existing antagonistic systems, this circumferential actuator produces high extension strokes and high forces at pressures below 100 kPa. The presented actuator is simple to manufacture and the design is complementary to the geometry of many soft arms, which makes the actuator a suitable choice to improve the arms' maximum load.

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Investigating effects of different flue-wall deformation modes on the performance of anode baking furnaces for aluminum electrolysis

Investigating effects of different flue-wall deformation mod...

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ASME 2019 International mechanical engineering Congress and Exposition, IMECE 2019

作者： Tajik, Abdul Raouf Zaidani, Mouna Shamim, Tariq Abu Al-Rub, Rashid K. Mechanical Engineering Department Khalifa University P.O. Box 127788 Abu Dhabi United Arab Emirates Aerospace Engineering Department Khalifa University P.O. Box 127788 Abu Dhabi United Arab Emirates Mechanical Engineering Department Northern Illinois University IL60115 United States Mechanical Engineering Program University of Michigan-Flint MI48502 United States

ISBN: (纸本)9780791859452

In carbon anode baking furnaces, temperature and quality of carbon anodes are significantly affected by the deformation of the flue-walls, where the flue-gases flow and combustion occur. Flue-walls aging gives rise to non-homogeneous baking of the carbon anodes and results in deterioration of the anode quality, which eventually causes instabilities in aluminum reduction cells and overconsumption of anodes and energy. It is imperative to develop a fully coupled 3D multi-physics computational model which takes into account a large number of physical phenomena that play vital roles in the baking process and are affected by the flue-wall deformation mode. In the present study, the effects of flue-wall deformation modes on flue-wall cavity gas flow and anode temperature distribution are investigated. The pressure and flow distributions for different levels of flue-wall deformation are demonstrated. It is perceived that a 100 mm convex mode of flue-wall deformation leads to under-baking of anodes by almost 20 degC. For the concave mode of deformation, since the packing coke thickness reduces, overbaking of anode occurs. The methodology and results presented in the present research can be employed effectively by the aluminum industry in modifying the furnace geometrical and operational parameters to enhance baking uniformity after flue-wall is deformed. Copyright © 2019 ASME.

关键词： Computational fluid dynamics

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In Situ Alloying Enabled by Active Liquid Metal Filler for Self-Healing Composite Polymer Electrolytes

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Angewandte Chemie 2024年第47期136卷

作者： Dr. Kai Wu Dr. Zhengyu Ju Dr. Bowen Zhang Prof. Amy C. Marschilok Prof. Esther S. Takeuchi Prof. Kenneth J. Takeuchi Prof. Guihua Yu Materials Science and Engineering Program and Walker Department of Mechanical Engineering The University of Texas at Austin 78712 Austin TX USA Institute of Energy Sustainability Environment and Equity Stony Brook University 11794 Stony Brook NY USA Department of Chemistry Stony Brook University 11794 Stony Brook NY USA Interdisciplinary Science Department Brookhaven National Laboratory 11973 Upton NY USA Department of Materials Science and Chemical Engineering Stony Brook University 11794 Stony Brook NY USA

Solid inorganics, known for kinetically inhibiting polymer crystallization and enhancing ionic conductivity, have attracted significant attention in solid polymer electrolytes. However, current composite polymer electrolytes (CPEs) are still facing challenges in Li metal batteries, falling short of inhibiting severe dendritic growth and resulting in very limited cycling life. This study introduces Ga 62.5 In 21.5 Sn 16 (Galinstan) liquid metal (LM) as an active liquid alternative to conventional passive solid fillers, aiming at realizing self-healing protection against dendrite problems. Compared to solid inorganics, for example silica, LM droplets could more significantly reduce polymer crystallinity and enhance Li-ion conductivity due to their liquid nature, especially at temperatures below the polymer melting point. More importantly, LMs are unraveled as dynamic chemical traps, which are capable of blocking and consuming lithium dendrites upon contact via in situ alloying during battery operation and further inhibiting dendritic growth due to the lower deposition energy barrier of the formed Li-LM alloy. As a proof of concept, by strategically designing an asymmetric CPE with the active LM filling, a solid-state Li/LiFePO 4 battery achieves promising full-cell functionality with notable rate performance and stable cycle life. This active filler-mediated self-healing approach could bring new insights into the battery design in versatile solid-state systems.

关键词： Solid-state battery Composite polymer electrolyte Liquid metal Lithium-metal battery Li dendrite

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Directional compliance in obstacle-aided navigation for snake robots

arXiv

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arXiv 2020年

作者： Wang, Tianyu Whitman, Julian Travers, Matthew Choset, Howie Department of Mechanical Engineering Carnegie Mellon University PittsburghPA15213 United States Robotics Institute Carnegie Mellon University PittsburghPA15213 United States

Snake robots have the potential to maneuver through tightly packed and complex environments. One challenge in enabling them to do so is the complexity in determining how to coordinate their many degrees-of-freedom to create purposeful motion. This is especially true in the types of terrains considered in this work: environments full of unmodeled features that even the best of maps would not capture, motivating us to develop closed-loop controls to react to those features. To accomplish this, this work uses proprioceptive sensing, mainly the force information measured by the snake robot’s joints, to react to unmodeled terrain. We introduce a biologically-inspired strategy called directional compliance which modulates the effective stiffness of the robot so that it conforms to the terrain in some directions and resists in others. We present a dynamical system that switches between modes of locomotion to handle situations in which the robot gets wedged or stuck. This approach enables the snake robot to reliably traverse a planar peg array and an outdoor three-dimensional pile of rocks. Copyright © 2020, The Authors. All rights reserved.

关键词： Piles

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Design and kinematics of a 3-DOF compliant triglide micromanipulator

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IOP Conference Series: Materials Science and engineering 2021年第1期1080卷

作者： Suraj Kumar Mishra C S Kumar Research Scholar Robotics and Intelligent Systems Laboratory Mechanical Engineering Department Indian Institute of Technology Kharagpur Kharagpur India Professor Robotics and Intelligent Systems Laboratory Mechanical Engineering Department Indian Institute of Technology Kharagpur Kharagpur India

This paper proposes a novel 3-degrees of freedom (DOF) compliant parallel micromanipulator. The design of the mechanism is based on triglide parallel manipulator. The compliant version of the triglide is prepared by making use of flexure joints. Displacement amplifiers are incorporated in the design to increase range of motions. The pseudo-rigid-body modeling technique is then used to formulate and solve the inverse kinematic problem for the design. To check the correctness and accuracy of the analytical kinematic model FEA simulations are performed in Abaqus-6.14 environment. Simulation results reveal that the proposed micromanipulator can perform different motions very effectively. Additionally, it is found that results predicted by the analytical model conform very closely to the simulation outcomes. The errors are very low, and the motions involve negligible parasitic motions.

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A study on modelling and analysis of 6-DOF industrial robot using ADAMS

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AIP Conference Proceedings 2023年第1期2680卷

作者： Amit Talli Ayub Ahmed Janvekar Ahmed A. Hussien Isam Qasem Pramodkumar S. Kataraki Mazlan Mohamed Hugeng Hugeng Automation and Robotics KLE Technological University Hubli – 580031 INDIA School of Mechanical Engineering VIT University Chennai Tamil Nadu - 600127 INDIA Department of Mechanical Engineering Al-Huson University College Al-Balqa Applied University Al-Huson Irbid JORDAN School of Mechanical Engineering Reva University Rukmini Knowledge Park Kattigenahalli Yelahanka Bengaluru – 560064 Karnataka INDIA Advanced Material Research Cluster Faculty of Bioengineering and Technology Jeli Campus Universiti Malaysia Kelantan Jeli 17600 MALAYSIA Electrical Engineering Department Universitas Tarumanagara Jl. Letjen S. Parman No. 1 Jakarta 11440 INDONESIA

In this paper, the modeling of an industrial robot is presented. The simulation of an industrial robot is carried out using the ADAMS multibody system. The computer-aided design model of an industrial robot is imported into ADAMS. The imported model in ADAMS is prepared for the simulation by adding markers or frames to the rigid bodies of an industrial robot. The relationship between the rigid bodies is established by applying constraints in ADAMS. The STEP function from the function builder is used to move the rigid bodies of an industrial robot. The STEP function is an expression that uses the initial and final conditions to create a smooth motion. The joint limits of an industrial robot are specified in the STEP function to trace the path of an end-effector, which represents the workspace of an industrial robot. Furthermore, the pose of an industrial robot using STEP expression is investigated in the postprocessor.

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Can I pour into it? Robot imagining open containability affordance of previously unseen objects via physical simulations

arXiv

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arXiv 2020年

作者： Wu, Hongtao Chirikjian, Gregory S. The Laboratory for Computational Sensing and Robotics The Johns Hopkins University BaltimoreMD21218 United States The Department of Mechanical Engineering National University of Singapore Singapore117575 Singapore

Open containers, i.e., containers without covers, are an important and ubiquitous class of objects in human life. In this letter, we propose a novel method for robots to "imagine" the open containability affordance of a previously unseen object via physical simulations. The robot autonomously scans the object with an RGB-D camera. The scanned 3D model is used for open containability imagination which quantifies the open containability affordance by physically simulating dropping particles onto the object and counting how many particles are retained in it. This quantification is used for open-container vs. non-open-container binary classification (hereafter referred to as open container classification). If the object is classified as an open container, the robot further imagines pouring into the object, again using physical simulations, to obtain the pouring position and orientation for real robot autonomous pouring. We evaluate our method on open container classification and autonomous pouring of granular material on a dataset containing 130 previously unseen objects with 57 object categories. Although our proposed method uses only 11 objects for simulation calibration, its open container classification aligns well with human judgements. In addition, our method endows the robot with the capability to autonomously pour into the 55 containers in the dataset with a very high success rate. We also compare to a deep learning method. Results show that our method achieves the same performance as the deep learning method on open container classification and outperforms it on autonomous pouring. Moreover, our method is fully explainable. Copyright © 2020, The Authors. All rights reserved.

关键词： Containers

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Examination of appearance conditions of singular stress fields at the vertex and along the side of interface in prismatic butt joint

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Journal of Japan Institute of Electronics Packaging 2020年第2期23卷 155-165页

作者： Miyazaki, Tatsujiro Sato, Keisuke Fujiwara, Takahiro Noda, Nao-Aki Sano, Yoshikazu Energy and Environment Program School of Engineering Faculty of Engineering University of the Ryukyus 1 Senbaru Nishihara-cho Nakagami-gun Okinawa903-0213 Japan Department of Mechanical Systems Engineering Graduate School of Engineering and Science University of the Ryukyus 1 Senbaru Nishihara-cho Nakagami-gun Okinawa903-0213 Japan Department of Mechanical Engineering Graduate School of Engineering Kyushu Institute of Technology 1-1 Sensui-cho Tobata-ku Kitakyushu-shi Fukuoka804-8550 Japan

In this paper, we discuss the bad pair condition causing a singular stress at a vertex of the interface in three dimensional (3D) prismatic butt joints in comparison with the bad pair condition along the side. 3D finite element (FE) eigenanalysis is applied to obtain the singular index. We found that the bad pair condition at a vertex is slightly different from the well-known 2D bad pair condition α(α- 2β) > 0 , which can be expressed using Dundurs' parameter (α, β). It should be noted that in most cases the bad pair can be judged by (α, β) except for some cases where the bad pair depends on the material combination even under the same (α, β). To clarify the difference, the bad pair conditions are compared on the (α, β) diagram. For convenience, a simple expression for a bad pair is proposed on the basis of the theoretical consideration, and the validity is confirmed numerically. We also confirm that the bad pair condition along the side of the interface can be expressed using Dundurs' parameter as α(α- 2β) > 0 . © 2020 Japan Institute of Electronics Packaging. All rights reserved.

关键词： Stresses

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