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A dynamics simulator for soft growing robots

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arXiv 2020年

作者： Jitosho, Rianna Agharese, Nathaniel Okamura, Allison Manchester, Zac Department of Mechanical Engineering Stanford University StanfordCA94305 United States Robotics Institute Carnegie Mellon University PittsburghPA15213 United States

Simulating soft robots in cluttered environments remains an open problem due to the challenge of capturing complex dynamics and interactions with the environment. Furthermore, fast simulation is desired for quickly exploring robot behaviors in the context of motion planning. In this paper, we examine a particular class of inflated-beam soft growing robots called "vine robots", and present a dynamics simulator that captures general behaviors, handles robot-object interactions, and runs faster than real time. The simulator framework uses a simplified multi-link, rigid-body model with contact constraints. To narrow the sim-to-real gap, we develop methods for fitting model parameters based on video data of a robot in motion and in contact with an environment. We provide examples of simulations, including several with fit parameters, to show the qualitative and quantitative agreement between simulated and real behaviors. Our work demonstrates the capabilities of this high-speed dynamics simulator and its potential for use in the control of soft robots. Copyright © 2020, The Authors. All rights reserved.

关键词： Motion planning

Haptic shared steering control with an adaptive level of authority based on time-to-line crossing ⁎

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IFAC-PapersOnLine 2019年第19期52卷 49-54页

作者： Hugo M. Zwaan Sebastiaan M. Petermeijer David A. Abbink Department of Cognitive Robotics Faculty of Mechanical Engineering Delft University of Technology Delft the Netherlands

Traditional driver-automation interaction trades control over the vehicle back and forth between driver and automation. Haptic shared control offers an alternative by continuously sharing the control through torques on the steering wheel and pedals. When designing additional feedback torques, part of the design choice lies in the stiffness around the neutral steering point: also called the Level of Haptic Authority (LoHA), which is usually static and tuned to balance safety benefits (better at high LoHA) with conflicts torques in case of different intentions between automation and driver (higher conflict torques with increased LoHA). In this paper we explore the idea of situation-adaptive LoHA: in this case during lane-keeping by changing the LoHA based on time to lane crossing (TLC). Consequently, when safety margins are high (e.g., when driving on a wide road) the LoHA is low, but the LoHA would only increase when safety margins decrease. We propose two alternative design approaches to apply the LoHA: symmetrically and asymmetrically (i.e., only increase of LoHA in the direction of the low TLC). We compared these design in an explorative driving simulator study (n=14) to driving with two static LoHA designs (low and high). We found that compared to the high LoHA controller, both adaptive LoHA controllers designs resulted in similar safety margins, but at decreased conflict torques. Hence, a TLC-based adaptive LoHA controller seems to be an effective approach to mitigate conflicts while maintaining the safety benefits associated with HSC.

关键词： Haptic Shared Control Adaptive Level of Haptic Authority Human-Machine interaction driving simulator

Chemo-mechanical model of a cell as a stochastic active gel

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arXiv 2021年

作者： Deshpande, Vikram DeSimone, Antonio McMeeking, Robert Recho, Pierre Engineering Department University of Cambridge Cambridge United Kingdom Scuola Internazionale Superiore di Studi Avanzati TriesteI-34136 Italy The BioRobotics Institute Department of Excellence in Robotics and A.I. Sant’Anna School for Advanced Studies PisaI-56127 Italy Mechanical Engineering and Materials Departments University of California Santa Barbara United States School of Engineering University of Aberdeen Aberdeen United Kingdom Université Grenoble Alpes Laboratoire Interdisciplinaire de Physique CNRS GrenobleF-38000 France

While it is commonly observed that the shape dynamics of mammalian cells can undergo large random fluctuations, theoretical models aiming at capturing cell mechanics often focus on the deterministic part of the motion. In this paper, we present a framework that couples an active gel model of the cell mechanical scaffold with the complex cell metabolic system stochastically delivering the chemical energy needed to sustain an active stress in the scaffold. Our closure assumption setting the magnitude of the fluctuations is that the chemo-mechanical free energy of the cell is controlled at a target homeostatic value. Our model rationalizes the experimental observation that the cell shape fluctuations depend on the mechanical environment that constraints the cell. We apply our framework to the simple case of a cell migrating on a one dimensional track to successfully capture the different regimes of the cell mean square displacement along the track as well as the magnitude of the long time scale effective diffusive motion of the cell. © 2021, CC BY-NC-ND.

关键词： Cells

Inertial Microfluidic-Assisted Rapid Detection of Chemical Contaminant in Foods Using Quantum Dots-Based Molecular Imprinting Sensor

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SSRN

SSRN 2023年

作者： Feng, Shaolong Lin, Yang Xu, Jie Lu, Xiaonan Food Nutrition and Health Program Faculty of Land and Food Systems The University of British Columbia VancouverBCV6T 1Z4 Canada Department of Food Science and Agricultural Chemistry McGill University Macdonald Campus 21111 Lakeshore Road Sainte-Anne-de-BellevueQCH9X 3V9 Canada Department of Mechanical and Industrial Engineering University of Illinois at Chicago ChicagoIL60607 United States University of Rhode Island United States

Integration of sample pretreatment, separation and detection in simple steps for food chemical contaminant analysis is challenging due to the complexity of food matrices. A novel analytical approach of using quantum dots-based molecular imprinting fluorescence sensor (QDs@MIPs) combined with inertial separation microfluidic device for separation and detection of enrofloxacin is presented in this study. The microfluidic device was designed based on laminar flow principle combined with Dean-coupled inertial migration of particles in spiral microchannels. Micron-sized QDs@MIPs sensing particles were synthesized for selective separation and sensitive detection of enrofloxacin. Separation of QDs@MIPs was achieved via parallel migration from the original suspension solution to another buffer solution in the same spiral microchannel with a high separation efficiency of 97.7±1.6%. Fluorescence intensity of QDs@MIPs was quenched in the presence of enrofloxacin and showed a linearity in the range of 0.1-50 µg/mL with limit of detection of 0.059 µg/mL. On-chip analyses were performed to detect enrofloxacin in both standard samples and contaminated swine muscle. This microfluidic-assisted fluorescence sensing system provides a solution to integrate sample pretreatment, separation and detection together to realize rapid analysis of food contaminants with high selectivity and sensitivity. © 2023, The Authors. All rights reserved.

关键词： Microchannels

Symmetries and synchronization from whole-neural activity in C. elegans connectome: Integration of functional and structural networks

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arXiv 2024年

作者： Avila, Bryant Augusto, Pedro Phillips, David Gili, Tommaso Zimmer, Manuel Makse, Hernán A. Levich Institute and Physics Department City College of New York New YorkNY10031 United States Vienna Austria Vienna Biocenter PhD Program Doctoral School the University of Vienna Medical University of Vienna Vienna Austria Mechanical Engineering Department University of New Mexico AlbuquerqueNM87131 United States Networks Unit IMT Scuola Alti Studi Lucca Piazza San Francesco 15 Lucca55100 Italy Department of Radiology Neuroradiology Service Memorial Sloan Kettering Cancer Center New YorkNY10065 United States CUNY Neuroscience Graduate Center City University of New York New YorkNY10031 United States

Understanding the dynamical behavior of complex systems from their underlying network architectures is a long-standing question in complexity theory. Therefore, many metrics have been devised to extract network features like motifs, centrality, and modularity measures. It has previously been proposed that network symmetries are of particular importance since they are expected to underly the synchronization of a system’s units, which is ubiquitously observed in nervous system activity patterns. However, perfectly symmetrical structures are difficult to assess in noisy measurements of biological systems, like neuronal connectomes. Here, we devise a principled method to infer network symmetries from combined connectome and neuronal activity data. Using nervous system-wide population activity recordings of the *** backward locomotor system, we infer structures in the connectome called fibration symmetries, which can explain which group of neurons synchronize their activity. Our analysis suggests functional building blocks in the animal’s motor periphery, providing new testable hypotheses on how descending interneuron circuits communicate with the motor periphery to control behavior. Our approach opens a new door to exploring the structure-function relations in other complex systems, like the nervous systems of larger animals. © 2024, CC BY.

关键词： Synchronization

Inter-Site Distance Effect in Electrocatalysis

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Angewandte Chemie 2025年

作者： Jiongcan Xiang Pengfei Wang Panpan Li Min Zhou Guihua Yu Zhaoyu Jin Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Chengdu 611731 China College of Materials Science and Engineering Sichuan University Chengdu 610065 China State Key Laboratory of Electroanalytical Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 China Materials Science and Engineering Program and Walker Department of Mechanical Engineering the University of Texas at Austin Austin TX 78712 USA

The inter-site distance effect (ISDE) has gained significant attention in heterogeneous catalysis, challenging classical models that treat adjacent nonbonded sites as isolated. Recent studies demonstrate that these sites can exhibit long-range cooperative interactions, enhancing reaction efficiencies. Fully leveraging the ISDE to overcome limitations in site reactivity requires a multidisciplinary approach and advanced techniques. This review provides a comprehensive overview of ISDE in electrocatalysis, starting with strategies for synthesizing materials with tunable inter-site distances. It examines ISDE across various catalyst models, including monometallic and heteronuclear atomic sites, active sites within clusters, and the lattice of nanocatalysts, focusing on their electronic structures, spatial geometries, and synergistic interactions. Advanced characterization and computational methods are highlighted as essential for identifying inter-site structures and distances, providing a systematic framework for understanding ISDE's role in electrocatalysis. The review also proposes best practices for studying ISDE, addressing current challenges and offering future perspectives. These insights aim to inform the design of highly efficient catalysts, enhance the understanding of catalytic mechanisms, and contribute to the development of more efficient energy conversion technologies, providing a foundation for further research into optimizing electrocatalysts.

关键词： Electrocatalysis Inter-site distance Single-atom catalysts Site density

Learning Stable Models for Prediction and Control

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arXiv 2020年

作者： Mamakoukas, Giorgos Abraham, Ian Murphey, Todd D. Department of Mechanical Engineering Northwestern University Evanston IL60208 United States The Robotics Institute Carnegie Mellon University PittsburghPA15213 United States

This paper demonstrates the benefits of imposing stability on data-driven Koopman operators. The data-driven identification of stable Koopman operators (DISKO) is implemented using an algorithm [1] that computes the nearest stable matrix solution to a least-squares reconstruction error. As a first result, we derive a formula that describes the prediction error of Koopman representations for an arbitrary number of time steps, and which shows that stability constraints can improve the predictive accuracy over long horizons. As a second result, we determine formal conditions on basis functions of Koopman operators needed to satisfy the stability properties of an underlying nonlinear system. As a third result, we derive formal conditions for constructing Lyapunov functions for nonlinear systems out of stable data-driven Koopman operators, which we use to verify stabilizing control from data. Lastly, we demonstrate the benefits of DISKO in prediction and control with simulations using a pendulum and a quadrotor and experiments with a pusher-slider system. The paper is complemented with a video: https://***/view/learning-stable-koopman. Copyright © 2020, The Authors. All rights reserved.

关键词： Nonlinear systems

MOF-derived spinel NiMn2O4/CoMn2O4 heterojunction and its application in a high-performance photocatalyst and supercapacitor

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Journal of Environmental Chemical engineering 2023年第5期11卷

作者： Lee, Kuen-Chan Hsiao, Yu-Sheng Sung, Ming-Yen Chen, Yi-Lun Wu, Nian-Jheng Huang, Jen-Hsien Cho, Er-Chieh Weng, Huei Chu Hsu, Shih-Chieh Department of Science Education National Taipei University of Education No. 134 Section 2 Heping E. Road Da-an District Taipei City106 Taiwan Ph.D. Program in Medical Neuroscience College of Medical Science and Technology Taipei Medical University 250 Wuxing Street Taipei City110 Taiwan Department of Materials Science and Engineering National Taiwan University of Science and Technology No. 43 Section 4 Keelung Road Da-an District Taipei10607 Taiwan Department of Clinical Pharmacy School of Pharmacy College of Pharmacy Taipei Medical University 250 Wuxing Street Taipei City110 Taiwan Université Paris-Saclay CNRS Institut des Sciences Moléculaires d′Orsay Orsay91405 France Department of Green Material Technology Green Technology Research Institute CPC Corporation No. 2 Zuonan Rd. Nanzi District Kaohsiung City81126 Taiwan Department of Mechanical Engineering Chung Yuan Christian University No. 200 Chungpei Rd Chungli District Taoyuan City32023 Taiwan Department of Chemical and Materials Engineering Tamkang University No. 151 Yingzhuan Road Tamsui District New Taipei City25137 Taiwan

Metal oxide heterojunctions have attracted considerable attention in photocatalyst and supercapacitor applications. In this study, NiMn2O4/CoMn2O4 (NMO/CMO) heterojunctions were synthesized using ternary metal-organic frameworks (MOFs) as precursors. After calcination at 500 °C, the as-prepared NMO/CMO composite maintains the porous sheet-like morphology of the ternary MOF, exhibiting a highly porous structure. The heterostructured NMO/CMO composite demonstrates enhanced photocatalytic performance compared with pure NMO and CMO. This enhancement may be attributed to the well-aligned energy levels at the NMO/CMO interface, which effectively reduces charge recombination and facilitates the efficient transport of photogenerated carriers. In addition, the NMO/CMO heterojunction exhibits enhanced supercapacitor performance owing to the increased number of active redox sites and reduced charge transfer resistance. When tested at 3 A/g, the NMO/CMO composite displays a higher capacitance (756.4 F/g) than pure NMO (579.6 F/g) and CMO (519.6 F/g) and remarkable rate capability, maintaining a capacitance of 639 F/g even at 10 A/g. Notably, asymmetric supercapacitors fabricated using NMO/CMO and activated carbon can achieve an energy density of 32.18 W h/kg at 750 W/kg and superior cycling life, retaining 92.1% of its initial capacitance after 3000 cycles. © 2023 Elsevier Ltd

关键词： Heterojunctions

Repeatability measurement and kinematic identification of LBR iiwa 7 R800 using monocular camera

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Repeatability measurement and kinematic identification of LB...

2019 Conference on Advances in robotics, AIR 2019

作者： Jain, Aditya Singh, Hardeep Boby, Riby Abraham Saha, Subir Kumar Kumar, Swagat Roy, Sumantra Dutta Department of Mechanical Engineering Indian Institute of Technology Delhi New Delhi India TCS Innovation Lab Robotics and Embedded System Group Bangalore India Department of Electrical Engineering Indian Institute of Technology Delhi New Delhi India

ISBN: (纸本)9781450366502

关键词： Cameras