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Magnetoelastic coupling driven magnon gap in a honeycomb antiferromagnet

Physical Review B 2024年第10期110卷 104419页

作者： Jeongheon Choe Andrey Baydin Gaihua Ye Bowen Ma Cynthia Nnokwe Martin Rodriguez-Vega David Lujan Swati Chaudhary Fuyang Tay Jiaming He Hiroyuki Nojiri Jianshi Zhou Gregory A. Fiete Junichiro Kono Rui He Xiaoqin Li Department of Physics Center of Complex Quantum Systems Center for Dynamics and Control of Materials Department of Electrical and Computer Engineering Smalley–Curl Institute Department of Physics Applied Physics Graduate Program Smalley–Curl Institute Department of Mechanical Engineering Institute for Materials Research Department of Physics and Astronomy Department of Materials Science and NanoEngineering

Cobalt titanate, CoTiO3, is a honeycomb antiferromagnet recently confirmed experimentally to host Dirac magnons, topological spin-orbit excitons, and chiral phonons. Here, we investigate a magnon gap at the zone center which calls for a refined spin Hamiltonian. We propose a microscopic model for the magnon gap and attribute it to a lattice-distortion (phonon)-induced higher-order spin interaction. Strong magnetoelastic coupling in CoTiO3 is also evident in Raman spectra, in which the magnetic order exerts a stronger influence on phonons corresponding to in-plane ionic motions than those with out-of-plane motions. We further examine the evolution of the zone-center magnons in a high magnetic field up to 18.5 T via THz absorption spectroscopy measurements. Based on this field dependence, we propose a spin Hamiltonian that not only agrees with magnon dispersion measured by inelastic neutron scattering but also includes fewer exchange constants and a realistic anisotropy term. Our work highlights the broad implications of magnetoelastic coupling in the study of topologically protected bosonic excitations.

关键词： Magnetism Magnons Topological materials Raman spectroscopy Terahertz spectroscopy

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Coordinated Multi-arm 3D Printing using Reeb Decomposition

Coordinated Multi-arm 3D Printing using Reeb Decomposition

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

作者： Jayant Khatkar Fouad Sukkar Lee Clemon Ramgopal Mettu The Robotics Institute University of Technology Sydney Australia Department of Mechanical Science and Engineering University of Illinois Urbana-Champaign USA Department of Computer Science Tulane University USA

ISBN: (数字)9798350377705

ISBN: (纸本)9798350377712

Robotic additive manufacturing has the potential to replace traditional production techniques with more flexible, capable and efficient methods. However, this potential has not yet been realized due to the intrinsic physical limitations of extruders. Thus improved speed and efficiency lies in coordinated fabrication by multiple extruders. In this paper, we propose a framework for utilizing multiple extruders to collaboratively fabricate objects in a shared workspace. In contrast to related work, we make use of a Reeb decomposition method of the input model, which dramatically reduces the search space over feasible toolpaths but still results in highly effective allocation of model components to each extruder. We demonstrate superior performance of our approach in simulation as well as in hardware with a two-robot arm extruder system. When compared to a single extruder approach over a benchmark of 14 models, our method achieves a mean improvement of 72% in extruder utilization. When compared to two additional toolpath planning methods for multiple extruders, only our method is able to successfully complete a valid toolpath on all models. Prior methods fail on more than half of our benchmark due to reaching deadlocked states during toolpath planning. On the models for which all methods succeed, our approach achieves mean utilization improvements of 132% over zone-blocking and 12% over contour greedy. We demonstrate that our approach is also suitable for models with non-planar slicings, which yield further improvements in extruder utilization. For more results and information see: https://***/view/multi-arm-reeb.

关键词： Fabrication Robot kinematics Production Benchmark testing System recovery Three-dimensional printing Hardware Planning Resource management Intelligent robots

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Design and Develop a Vertical Box Smart Farm based on programmable Logic Controller

Design and Develop a Vertical Box Smart Farm based on Progra...

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International Conference on Advanced robotics and Mechatronics (ICARM)

作者： Thananop Tummawai Peeraput Prakhummin Kittisak Ledkaew Anocha Phongsatja Witayakorn Lunsungyang Somboon Sukpancharoen Department of Mechanical Engineering Khon Kaen University Khon Kaen Thailand Department of Automation Robotics and Intelligent Systems Khon Kaen University Khon Kaen Thailand Department of Agricultural Engineering Khon Kaen University Khon Kaen Thailand

ISBN: (数字)9798350385724

ISBN: (纸本)9798350385731

Agriculture plays an indispensable role in daily life, and presently, soilless cultivation techniques such as hydroponics enjoy widespread popularity. In efforts to advance this methodology, we have implemented a sophisticated programmable Logic Controllers (PLCs) system tailored for Nutrient Film Technique (NFT) hydroponic cultivation within a greenhouse setting. This system incorporates a diverse array of sensors designed to measure crucial parameters including water temperature, Electrical Conductivity (EC), and Potential of Hydrogen ion ($\mathbf{p H}$) levels. The PLCs is meticulously programmed to oversee and regulate the entire cultivation process seamlessly. Additionally, integration of a Raspberry Pi facilitates Internet of Things (IoT) functionalities, thereby enhancing convenience and enabling remote monitoring capabilities. We aim to conduct a comparative analysis between two distinct greenhouse systems: one under the control of the PLC, and the other devoid of such automated control, in order to discern and evaluate the disparities in plant growth and development between them. The study focuses on key variables such as canopy width and leaf count of Green Oak Lettuce over a 5 -week period, with the primary environmental factors influencing these variables being the levels of EC and pH in the nutrient solution. The findings of this study will provide valuable insights into the benefits of environmental control in greenhouse-based hydroponic cultivation of green oak lettuce, contributing to the advancement of sustainable and efficient agricultural practices.

关键词： Temperature sensors Temperature measurement Green products programmable logic devices Hydroponics Nutrients Stability analysis Internet of Things Remote monitoring Sensor arrays

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Online Robot Motion Planning Methodology Guided by Group Social Proxemics Feature

arXiv

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arXiv 2025年

作者： Mu, Xuan Liu, Xiaorui Guo, Shuai Chi, Wenzheng Wang, Wei Ge, Shuzhi Sam School of Automation Qingdao University Qingdao266000 China School of Automation Qingdao University Qingdao University Qingdao266000 China Robotics and Microsystems Center School of Mechanical and Electric Engineering Soochow University Suzhou215021 China School of Mechanical Engineering & Automation the Robotics Institute Beihang University Beijing100000 China Department of Electrical and Computer Engineering National University of Singapore Singapore117576 Singapore

Nowadays robot is supposed to demonstrate human-like perception, reasoning and behavior pattern in social or service application. However, most of the existing motion planning methods are incompatible with above requirement. A potential reason is that the existing navigation algorithms usually intend to treat people as another kind of obstacle, and hardly take the social principle or awareness into consideration. In this paper, we attempt to model the proxemics of group and blend it into the scenario perception and navigation of robot. For this purpose, a group clustering method considering both social relevance and spatial confidence is introduced. It can enable robot to identify individuals and divide them into groups. Next, we propose defining the individual proxemics within magnetic dipole model, and further established the group proxemics and scenario map through vector-field superposition. On the basis of the group clustering and proxemics modeling, we present the method to obtain the optimal observation positions (OOPs) of group. Once the OOPs grid and scenario map are established, a heuristic path is employed to generate path that guide robot cruising among the groups for interactive purpose. A series of experiments are conducted to validate the proposed methodology on the practical robot, the results have demonstrated that our methodology has achieved promising performance on group recognition accuracy and path-generation efficiency. This concludes that the group awareness evolved as an important module to make robot socially behave in the practical scenario. © 2025, CC BY-NC-ND.

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Design and Control Co-Optimization for Automated Design Iteration of Dexterous Anthropomorphic Soft Robotic Hands

arXiv

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arXiv 2024年

作者： Mannam, Pragna Liu, Xingyu Zhao, Ding Oh, Jean Pollard, Nancy Robotics Institute Carnegie Mellon University PA15213 United States Department of Mechanical Engineering Carnegie Mellon University PA15213 United States

We automate soft robotic hand design iteration by co-optimizing design and control policy for dexterous manipulation skills in simulation. Our design iteration pipeline combines genetic algorithms and policy transfer to learn control policies for nearly 400 hand designs, testing grasp quality under external force disturbances. We validate the optimized designs in the real world through teleoperation of pickup and reorient manipulation tasks. Our real world evaluation, from over 900 teleoperated tasks, shows that the trend in design performance in simulation resembles that of the real world. Furthermore, we show that optimized hand designs from our approach outperform existing soft robot hands from prior work in the real world. The results highlight the usefulness of simulation in guiding parameter choices for anthropomorphic soft robotic hand systems, and the effectiveness of our automated design iteration approach, despite the sim-to-real gap. Copyright © 2024, The Authors. All rights reserved.

关键词： Robotic arms

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A geometric method based on space arc for pose-configuration simultaneous planning of segmented hyper-redundant manipulators

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Science China(Technological Sciences) 2021年第11期64卷 2389-2407页

作者： HU ZhongHua YUAN Han XU WenFu YANG TaiWei LIU TianLiang LIANG Bin School of Mechanical Engineering and Automation Harbin Institute of TechnologyShenzhen 518055China State Key Laboratory^of Robotics and System Harbin Institute of TechnologyHarbin 150001China Department of Automation Tsinghua UniversityBeijing 100084China

A segmented hyper-redundant manipulator can perform complicated operation tasks in a confined space due to its high flexibility and dexterity. However, the trajectory planning in a narrow space and obstacles environment is very challenging for the manipulator. In this paper, we propose a geometry method to simultaneously plan the end-effector pose and manipulator’s configuration. Firstly, the geometries of each segment are described by an inscribed arc(IA) and a circumscribed arc(CA). Then,the whole kinematics chain is considered as an inscribed curve(IC) or a circumscribed curve(CC) which are composed of multiple IAs or CAs. Furthermore, the IC and CC of the manipulator are divided into multiple spatial single-arc and double-arc groups according to requirements. The pose-configuration simultaneous planning is realized by the spatial single-arc/double-arc modeling and joints angles solving. By numerical iteration, the spatial arcs’ parameters are determined according to desired pose and boundary condition of obstacle avoidance. The angles of joints are analytically solved when the above parameters are known. Finally, a narrow space detection task is simulated and experimented respectively. The results verify the proposed method.

关键词： segmented hyper-redundant manipulator pose-configuration simultaneous planning spatial arc modeling obstacle avoidance geometric planning

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Diffusiophoresis in the presence of a pH gradient

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Physical Review Fluids 2022年第11期7卷 110513-110513页

作者： Suin Shim Janine K. Nunes Guang Chen Howard A. Stone Department of Mechanical and Aerospace Engineering Princeton University Princeton New Jersey 08544 USA Department of Advanced Manufacturing and Robotics College of Engineering Peking University Beijing 100871 China

Diffusiophoresis is the spontaneous motion of particles under gradients of solutes. In electrolyte-driven diffusiophoresis, the zeta potential of the particles is an important surface property that characterizes diffusiophoretic mobility. However, the zeta potential is not a fixed material property and colloidal surfaces often show varying potentials depending on the physicochemical properties of the surrounding fluid, e.g., solute type, ionic strength, and pH. In this paper, we study experimentally and theoretically pH-dependent diffusiophoresis of polystyrene particles using a dead-end pore geometry. In particular, the influence of the isoelectric point (pI) on diffusiophoresis is demonstrated in the absence and presence of wall diffusioosmosis. Throughout the paper, we show with experiments and model calculations how the pH-dependent diffusiophoresis and diffusioosmosis influence the particle motion in dead-end pore configurations, including changes that occur when there is a sign change in the zeta potential near the pI.

关键词： Diffusiophoresis Electrokinetic flows Microfluidics Colloids

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On the Potentials of Utilizing a Handheld Bioprinter for in Vivo Treatment of Volumetric Muscle Loss Injuries

On the Potentials of Utilizing a Handheld Bioprinter for in ...

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International Symposium on Medical robotics (ISMR)

作者： Omid Rezayof Susheela Sharma Meenakshi Kamaraj Johnson v. John Farshid Alambeigi Walker Department of Mechanical Engineering and Texas Robotics University of Texas at Austin TX USA Terasaki Institute for Biomedical Innovation Los Angeles CA USA

ISBN: (数字)9798350377118

ISBN: (纸本)9798350377125

In this study, with the goal of enhancing and evaluating existing treatment procedures for large Volumetric Muscle Loss (VML) injuries, we propose design and quantitative performance evaluation of a handheld in vivo bioprinter. Existing bioprinting handheld devices are either have been used for treatment of small injuries or miss to quantitatively verify the precision and accuracy of printing procedure and limited these evaluations to qualitative analysis. To simultaneously address these issues, in this work, we first proposed design and development of a bioprinting system. Next, to quantitatively address the accuracy of the developed handheld device, we first proposed a calibration procedure and then performed a set of experiments to quantitatively evaluate and characterize the performance of printing with this device.

关键词： Printing Performance evaluation Bioprinting In vivo Accuracy Muscles Wounds

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MambaST: A Plug-and-Play Cross-Spectral Spatial-Temporal Fuser for Efficient Pedestrian Detection

arXiv

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arXiv 2024年

作者： Gao, Xiangbo Kanu-Asiegbu, Asiegbu Miracle Du, Xiaoxiao The Robotics Department University of Michigan Ann ArborMI48109 United States The Department of Mechanical Engineering University of Michigan Ann ArborMI48109 United States

This paper proposes MambaST, a plug-and-play cross-spectral spatial-temporal fusion pipeline for efficient pedestrian detection. Several challenges exist for pedestrian detection in autonomous driving applications. First, it is difficult to perform accurate detection using RGB cameras under dark or low-light conditions. Cross-spectral systems must be developed to integrate complementary information from multiple sensor modalities, such as thermal and visible cameras, to improve the robustness of the detections. Second, pedestrian detection models are latency-sensitive. Efficient and easy-to-scale detection models with fewer parameters are highly desirable for real-time applications such as autonomous driving. Third, pedestrian video data provides spatial-temporal correlations of pedestrian movement. It is beneficial to incorporate temporal as well as spatial information to enhance pedestrian detection. This work leverages recent advances in the state space model (Mamba) and proposes a novel Multi-head Hierarchical Patching and Aggregation (MHHPA) structure to extract both fine-grained and coarse-grained information from both RGB and thermal imagery. Experimental results show that the proposed MHHPA is an effective and efficient alternative to a Transformer model for cross-spectral pedestrian detection. Our proposed model also achieves superior performance on small-scale pedestrian detection. The code is available at https://***/XiangboGaoBarry/MambaST. Copyright © 2024, The Authors. All rights reserved.

关键词： Thermography (imaging)

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360FusionNeRF: Panoramic Neural Radiance Fields with Joint Guidance

360FusionNeRF: Panoramic Neural Radiance Fields with Joint G...

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

作者： Shreyas Kulkarni Peng Yin Sebastian Scherer Department of Mechanical Engineering Indian Institute of Technology Madras Robotics Institute Carnegie Mellon University Pittsburgh PA USA

Based on the neural radiance fields (NeRF), we present a pipeline for generating novel views from a single 360° panoramic image. Prior research relied on the neighborhood interpolation capability of multi-layer perceptions to complete missing regions caused by occlusion. This resulted in artifacts in their predictions. We propose 360FusionNeRF, a semi-supervised learning framework that employs geometric supervision and semantic consistency to guide the progressive training process. Firstly, the input image is reprojected to 360° images, and depth maps are extracted at different camera positions. In addition to the NeRF color guidance, the depth supervision enhances the geometry of the synthesized views. Furthermore, we include a semantic consistency loss that encourages realistic renderings of novel views. We extract these semantic features using a pre-trained visual encoder CLIP, a Vision Transformer (ViT) trained on hundreds of millions of diverse 2D photographs mined from the web with natural language supervision. Experiments indicate that our proposed method is capable of producing realistic completions of unobserved regions while preserving the features of the scene. 360FusionNeRF consistently delivers state-of-the-art performance when transferring to synthetic Structured3D dataset (PSNR ~ 5%, SSIM ~3% LPIPS ~13%), real-world Matterport3D dataset (PSNR ~3%, SSIM ~3% LPIPS ~9%) and Replica360 dataset (PSNR ~8%, SSIM ~2% LPIPS ~18%). We provide the source code at https://***/MetaSLAM/360FusionNeRF.

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