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DAFNI: A computational platform to support infrastructure systems research

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Proceedings of the Institution of civil Engineers: Smart Infrastructure and Construction 2023年第3期176卷 108-116页

作者： Matthews, Brian Hall, Jim Batty, Michael Blainey, Simon Cassidy, Nigel Choudhary, Ruchi Coca, Daniel Hallett, Stephen Harou, Julien J James, Phil Lomax, Nik Oliver, Peter Sivakumar, Aruna Tryfonas, Theodoros Varga, Liz Scientific Computing Department Science and Technology Facilities Council Didcot United Kingdom School of Geography and the Environment University of Oxford Oxford United Kingdom Centre for Advanced Spatial Analysis University College London London United Kingdom Transportation Research Group Faculty of Engineering and Physical Sciences University of Southampton Southampton United Kingdom Department of Civil Engineering University of Birmingham Birmingham United Kingdom Department of Engineering University of Cambridge Cambridge United Kingdom Department of Automatic Control and Systems Engineering University of Sheffield Sheffield United Kingdom Centre for Environmental and Agricultural Informatics Cranfield University Cranfield United Kingdom Department of Mechanical Aerospace and Civil Engineering University of Manchester Manchester United Kingdom School of Engineering Newcastle University Newcastle United Kingdom School of Geography University of Leeds Leeds United Kingdom Department of Civil and Environmental Engineering Imperial College London London United Kingdom Department of Civil Engineering University of Bristol Bristol United Kingdom Department of Civil Environmental and Geomatic Engineering University College London London United Kingdom

Research into the engineering of infrastructure systems is increasingly data intensive. Researchers build computational models to explore scenarios such as investigating the merits of infrastructure plans, analysing historical data to inform system operations or assessing the impacts of infrastructure on the environment. Models are more complex, at higher resolution and with larger coverage. Researchers also require a 'multi-systems' approach to explore interactions between systems, such as energy and water with urban development, and across scales, from buildings and streets to regions or nations. Consequently, researchers need enhanced computational resources to support cross-institutional collaboration and sharing at scale. The Data and Analytics Facility for National Infrastructure (DAFNI) is an emerging computational platform for infrastructure systems research. It provides high-throughput compute resources so larger data sets can be used, with a data repository to upload data and share these with collaborators. Users' models can also be uploaded and executed using modern containerisation techniques, giving platform independence, scaling and sharing. Further, models can be combined into workflows, supporting multi-systems modelling and generating visualisations to present results. DAFNI forms a central resource accessible to all infrastructure systems researchers in the UK, supporting collaboration and providing a legacy, keeping data and models available beyond the lifetime of a project. © 2023 Emerald Publishing Limited: All rights reserved.

关键词： Urban growth

Robust Bipedal Locomotion: Leveraging Saltation Matrices for Gait Optimization

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arXiv 2022年

作者： Tucker, Maegan Csomay-Shanklin, Noel Ames, Aaron D. The Department of Mechanical and Civil Engineering California Institute of Technology PasadenaCA91125 United States The Department of Control and Dynamical Systems California Institute of Technology PasadenaCA91125 United States

The ability to generate robust walking gaits on bipedal robots is key to their successful realization on hardware. To this end, this work extends the method of Hybrid Zero Dynamics (HZD) - which traditionally only accounts for locomotive stability via periodicity constraints under perfect impact events - through the inclusion of the saltation matrix with a view toward synthesizing robust walking gaits. By jointly minimizing the norm of the extended saltation matrix and the torque of the robot directly in the gait generation process, we demonstrate that the synthesized gaits are more robust than gaits generated with either term alone;these results are shown in simulation and on hardware for the AMBER-3M planar biped and the Atalante lower-body exoskeleton (both with and without a human subject). The end result is experimental validation that combining saltation matrices with HZD methods produces more robust bipedal walking in practice. Copyright © 2022, The Authors. All rights reserved.

关键词： Exoskeleton (Robotics)

Multidimensional Opinion Dynamics with Heterogeneous Bounded Confidences and Random Interactions

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arXiv 2024年

作者： Cheng, Jiangjiang Chen, Ge Mei, Wenjun Bullo, Francesco School of Mathematical Sciences University of Chinese Academy of Sciences Beijing100049 China Key Laboratory of Systems and Control Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China Department of Mechanics and Engineering Science Peking University Beijing100871 China Department of Mechanical Engineering The Center of Control Dynamical-Systems and Computation University of California Santa BarbaraCA93106-5070 United States

This paper introduces a heterogeneous multidimensional bounded confidence (BC) opinion dynamics with random pairwise interactions, whereby each pair of agents accesses each other’s opinions with a specific probability. This revised model is motivated by the observation that the standard Hegselmann-Krause (HK) dynamics requires unrealistic all-to-all interactions at certain configurations. For this randomized BC opinion dynamics, regardless of initial opinions and positive confidence bounds, we show that the agents’ states converge to fixed final opinions in finite time almost surely and that the convergence rate follows a negative exponential distribution in mean square. Furthermore, we establish sufficient conditions for the heterogeneous BC opinion dynamics with random interactions to achieve consensus in finite time. Copyright © 2024, The Authors. All rights reserved.

关键词： Random processes

Model-Free Safety-Critical control for Robotic systems

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arXiv 2021年

作者： Molnar, Tamas Gabor Cosner, Ryan K. Singletary, Andrew W. Ubellacker, Wyatt Ames, Aaron D. The Control and Dynamical Systems The Department of Mechanical and Civil Engineering California Institute of Technology PasadenaCA91125 United States

This paper presents a framework for the safety-critical control of robotic systems, when safety is defined on safe regions in the configuration space. To maintain safety, we synthesize a safe velocity based on control barrier function theory without relying on a – potentially complicated – high-fidelity dynamical model of the robot. Then, we track the safe velocity with a tracking controller. This culminates in model-free safety critical control. We prove theoretical safety guarantees for the proposed method. Finally, we demonstrate that this approach is application-agnostic. We execute an obstacle avoidance task with a Segway in high-fidelity simulation, as well as with a Drone and a Quadruped in hardware experiments. © 2021, CC BY.

关键词： Robotics

Verifying Safe Transitions between Dynamic Motion Primitives on Legged Robots

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arXiv 2021年

作者： Ubellacker, Wyatt Csomay-Shanklin, Noel Molnar, Tamas G. Ames, Aaron D. The Department of Control and Dynamical Systems the Department of Mechanical and Civil Engineering California Institute of Technology PasadenaCA United States

Functional autonomous systems often realize complex tasks by utilizing state machines comprised of discrete primitive behaviors and transitions between these behaviors. This architecture has been widely studied in the context of quasi-static and dynamics-independent systems. However, applications of this concept to dynamical systems are relatively sparse, despite extensive research on individual dynamic primitive behaviors, which we refer to as "motion primitives." This paper formalizes a process to determine dynamic-state aware conditions for transitions between motion primitives in the context of safety. The result is framed as a "motion primitive graph" that can be traversed by standard graph search and planning algorithms to realize functional autonomy. To demonstrate this framework, dynamic motion primitives—including standing up, walking, and jumping—and the transitions between these behaviors are experimentally realized on a quadrupedal robot. Copyright © 2021, The Authors. All rights reserved.

关键词： dynamical systems

HOW SOCIAL INFLUENCE AFFECTS THE WISDOM OF CROWDS IN INFLUENCE NETWORKS

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arXiv 2022年

作者： Tian, Ye Wang, Long Bullo, Francesco Center for Systems and Control College of Engineering Peking University Beijing100871 China Mechanical Engineering Department The Center of Control Dynamical Systems and Computation University of California at Santa Barbara Santa BarbaraCA93106 United States

A long-standing debate is whether social influence improves the collective wisdom of a crowd or undermines it. This paper addresses the question based on a naïve learning setting in influence systems theory: in our models individuals evolve their estimates of an unknown truth according to the weighted-average opinion dynamics. A formal mathematization is provided with rigorous theoretical analysis. We obtain various conditions for improving, optimizing and undermining the crowd accuracy, respectively. We prove that if the wisdom of a finite-size group is improved, then the collective estimate converges to the truth as the group size increases. We show that whether social influence improves or undermines the wisdom is determined by the social power allocations in the influence system: if the influence system allocates relatively larger social power to relatively more accurate individuals, it improves the wisdom;on the contrary, if the influence system assigns less social power to more accurate individuals, it undermines the wisdom. At a population level, individuals' susceptibilities to interpersonal influence and network centralities are both crucial. To improve the wisdom, more accurate individuals should be less susceptible and have larger network centralities. Particularly, in democratic influence networks, if relatively more accurate individuals are relatively less susceptible, the wisdom is improved;if more accurate individuals are more susceptible, the wisdom is undermined, which is consistent with the reported empirical evidence. Our investigation provides a theoretical framework for understanding the role social influence plays in the emergence of collective wisdom. Copyright © 2022, The Authors. All rights reserved.

关键词： Economic and social effects

Situation and Ordering based control of Drainage of a Group of Polders

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IFAC-PapersOnLine 2024年第2期58卷 31-37页

作者： Ronald van Nooijen Alla Kolechkina Thomas Berends Elgard van Leeuwen Water Management Department Faculty of Civil Engineering and Geosciences Delft University of Technology Delft Netherlands Delft Center for Systems and Control Faculty of Mechanical Maritime and Materials Engineering Delft University of Technology Delft Netherlands Innovation & Impact Centre Delft University of Technology Delft Netherlands

A polder-boezem system consists of a (large) number of polders that pump their drainage water into a network of watercourses and lakes. A few large pump stations then pump the drainage water into rivers or the sea. In some cases a sluice gate is used when water levels allow it. A receding horizon control algorithm for a polder-boezem system is presented where the selection of the control action is based on a prescribed order of use for the different states of available pumps and sluices. It is an extension of an earlier algorithm that operated boezem pump stations only. A further extension is proposed that will allow inclusion of the control of polder pumps. Arguments are presented to support the claim that, from the point of view of transparency, this algorithm is better suited to the control of polder-boezem systems than receding horizon control with a traditional objective function.

关键词： Water management Hydroinformatics Optimal control operation of water resources system Model predictive control

Scour Repair of Bridges Through Vibration Monitoring and Related Challenges 1st

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Scour Repair of Bridges Through Vibration Monitoring and Rel...

1st Conference of the European Association on Quality control of Bridges and Structures, EUROSTRUCT 2021

作者： Micu, E. Alexandra Khan, Muhammad Arslan Bhowmik, Basuraj Florez, Miguel Casero Obrien, Eugene Bowe, Cathal Pakrashi, Vikram Dynamical Systems and Risk Laboratory School of Mechanical and Materials Engineering University College Dublin Dublin Ireland School of Civil Engineering University College Dublin Dublin Ireland Iarnród Éireann Dublin Ireland Science Foundation Ireland MaREI Centre University College Dublin Dublin Ireland UCD Centre for Mechanics University College Dublin Dublin Ireland

ISBN: (纸本)9783030918767

Scour in railway bridges is often an important problem, especially for old bridges. In this regard, the assessment of full-scale bridges to establish scour repair adequacy or efficiency is an important question. Typically, scour weakens the bridge structure by modifying its boundary conditions. Such changes, when significant enough, can lead to changes in modal properties and in vibrations measurements with respect to the ideal baseline. On the other hand, a repair attempts to restore the release in boundary conditions. Consequently, a repair also changes the modal properties and the dynamic responses. This indicates that significant and consistent changes of bridges before and after repair can indicate the adequacy and efficiency of scour repair. This paper addresses this idea by carrying out a full-scale test on scour repair of a train bridge in Ireland. The bridge is monitored on two abutments with several wireless accelerometers while the bridge is operational. Both ambient and train passage events are considered in terms of collection of vibration data. While it is not possible to discern the difference between repaired and scour-damaged conditions, it is observed that time domain markers may be more consistent in indicating repair efficiency as compared to its frequency domain counterpart. This full-scale demonstration is expected to act as a full-scale example for vibration-based repair monitoring and performance criteria for future detection algorithms. The approach does not require the bridge to be closed down and can be relevant for other sensors as well. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Frequency domain analysis

THE YAKUBOVICH S-LEMMA REVISITED: STABILITY AND CONTRACTIVITY IN NON-EUCLIDEAN NORMS

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arXiv 2022年

作者： Proskurnikov, Anton V. Davydov, Alexander Bullo, Francesco Department of Electronics and Telecommunications Politecnico di Torino Turin Italy Department of Mechanical Engineering The Center for Control Dynamical Systems and Computation University of California Santa Barbara United States

The celebrated S-Lemma was originally proposed to ensure the existence of a quadratic Lyapunov function in the Lur'e problem of absolute stability. A quadratic Lyapunov function is, however, nothing else than a squared Euclidean norm on the state space (that is, a norm induced by an inner product). A natural question arises as to whether squared non-Euclidean norms V (x) = ǁxǁ2 may serve as Lyapunov functions in stability problems. This paper presents a novel non-polynomial S-Lemma that leads to constructive criteria for the existence of such functions defined by weighted p norms. Our generalized S-Lemma leads to new absolute stability and absolute contractivity criteria for Lur'e-type systems, including, for example, a new simple proof of the Aizerman and Kalman conjectures for positive Lur'e *** Codes 34H05, 93C15 Copyright © 2022, The Authors. All rights reserved.

关键词： Lyapunov functions