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arXiv 2017年

作者： Mei, Wenjun Cisneros-Velarde, Pedro Chen, Ge Friedkin, Noah E. Bullo, Francesco Automatic Control Laboratory ETH Zurich Switzerland Center of Control Dynamical Systems and Computation University of California Santa Barbara United States Department of Sociology University of California Santa Barbara United States Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing China

Social balance theory describes allowable and forbidden configurations of the topologies of signed directed social appraisal networks. In this paper, we propose two discrete-time dynamical systems that explain how an appraisal network converges to social balance from an initially unbalanced configuration. These two models are based on two different socio-psychological mechanisms respectively: the homophily mechanism and the influence mechanism. Our main theoretical contribution is a comprehensive analysis for both models in three steps. First, we establish the well-posedness and bounded evolution of the interpersonal appraisals. Second, we fully characterize the set of equilibrium points;for both models, each equilibrium network is composed of an arbitrary number of complete subgraphs satisfying structural balance. Third, we establish the equivalence among three distinct properties: non-vanishing appraisals, convergence to all-to-all appraisal networks, and finite-time achievement of social balance. In addition to theoretical analysis, Monte Carlo validations illustrate how the non-vanishing appraisal condition holds for generic initial conditions in both models. Moreover, a numerical comparison between the two models indicates that the homophily-based model might be a more universal explanation for the emergence of social balance. Finally, adopting the homophily-based model, we present numerical results on the mediation and globalization of local conflicts, the competition for allies, and the asymptotic formation of a single versus two factions.91D30, 37N99, 93A30 Copyright © 2017, The Authors. All rights reserved.

关键词： Multi agent systems

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The spectral element method as an efficient tool for transient simulations of hydraulic systems

arXiv

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arXiv 2017年

作者： Mennemann, J.-F. Marko, L. Schmidt, J. Kemmetmüller, W. Kugi, A. Automation and Control Institute Complex Dynamical Systems TU Wien Gusshausstrasse 27-29 Vienna1040 Austria Christian Doppler Laboratory for Model-Based Process Control in the Steel Industry TU Wien Gusshausstrasse 27-29 Vienna1040 Austria

This paper presents transient numerical simulations of hydraulic systems in engineering applications using the spectral element method (SEM). Along with a detailed description of the underlying numerical method, it is shown that the SEM yields highly accurate numerical approximations at modest computational costs, which is in particular useful for optimization-based control applications. In order to enable fast explicit time stepping methods, the boundary conditions are imposed weakly using a numerically stable upwind discretization. The benefits of the SEM in the area of hydraulic system simulations are demonstrated in various examples including several simulations of strong water hammer effects. Due to its exceptional convergence characteristics, the SEM is particularly well suited to be used in real-time capable control applications. As an example, it is shown that the time evolution of pressure waves in a large scale pumped-storage power plant can be well approximated using a low-dimensional system representation utilizing a minimum number of dynamical states. Copyright © 2017, The Authors. All rights reserved.

关键词： Hydraulic equipment

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Fundamental limits and tradeoffs in autocatalytic pathways

arXiv

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arXiv 2017年

作者： Siami, Milad Motee, Nader Buzi, Gentian Bamieh, Bassam Khammash, Mustafa Doyle, John C. Institute for Data Systems and Society Massachusetts Institute of Technology CambridgeMA02319 United States Department of Mechanical Engineering and Mechanics Packard Laboratory Lehigh University BethlehemPA18015 United States State University of New York at Fredonia Department of Mechanical Engineering University of California Santa BarbaraCA93106 United States Department of Biosystems Science and Engineering Eth Zurich Mattenstrasse 26 Basel4058 Switzerland Control and Dynamical Systems California Institute of Technology PasadenaCA91125 United States

This paper develops some basic principles to study au-tocatalytic networks and exploit their structural properties in order to characterize their inherent fundamental limits and tradeoffs. In a dynamical system with autocatalytic structure, the system's output is necessary to catalyze its own production. We consider a simplified model of Glycolysis pathway as our motivating application. First, the properties of these class of pathways are investigated through a simplified two-state model, which is obtained by lumping all the intermediate reactions into a single intermediate reaction. Then, we generalize our results to autocatalytic pathways that are composed of a chain of enzymatically catalyzed intermediate reactions. We explicitly derive a hard limit on the minimum achievable L2-gain disturbance attenuation and a hard limit on its minimum required output energy. Finally, we show how these resulting hard limits lead to some fundamental tradeoffs between transient and steady-state behavior of the network and its net production. Copyright © 2017, The Authors. All rights reserved.

关键词： dynamical systems

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The resilient spacecraft executive: An architecture for risk-aware operations in uncertain environments

The resilient spacecraft executive: An architecture for risk...

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AIAA Space and Astronautics Forum and Exposition, SPACE 2016

作者： McGhan, Catharine L. R. Murrayy, Richard M. Vaquero, Tiago Williams, Brian C. Ingham, Michel D. Ono, Masahiro Estlin, Tara Lanka, Ravi Arslan, Oktay Elaasar, Maged E. Department of Control and Dynamical Systems California Institute of Technology 1200 E. California Blvd Mail Code 305-16 PasadenaCA91125 United States Department of Control and Dynamical Systems California Institute of Technology 1200 E. California Blvd Mail Code 107-81 PasadenaCA91125 United States Department of Aeronautics and Astronautics Massachusetts Institute of Technology 32 Vassar Street 32-224 CambridgeMA02139 United States Department of Aeronautics and Astronautics Massachusetts Institute of Technology 77 Massachusetts Avenue 33-330 32-227 CambridgeMA02139 United States Jet Propulsion Laboratory California Institute of Technology PasadenaCA91109 United States 4800 Oak Grove Drive Mail Stop 301-490 United States 4800 Oak Grove Drive Mail Stop 198-219 United States 4800 Oak Grove Drive Mail Stop 158-242 United States 4800 Oak Grove Drive Mail Stop 179-206 United States

ISBN: (数字)9781624104275

ISBN: (纸本)9781624104275

In this paper we discuss the latest results from the Resilient Space systems project, a joint effort between Caltech, MIT, NASA Jet Propulsion laboratory (JPL), and the Woods Hole Oceanographic Institution (WHOI). The goal of the project is to define a resilient, risk-aware software architecture for onboard, real-time autonomous operations that can robustly handle uncertainty in spacecraft behavior within hazardous and unconstrained environments, without unnecessarily increasing complexity. The architecture, called the Resilient Spacecraft Executive (RSE), has been designed to support three functions: (1) adapting to component failures to allow graceful degradation, (2) accommodating environments, science observations, and spacecraft capabilities that are not fully known in advance, and (3) making risk-aware decisions without waiting for slow ground-based reactions. In implementation, the bulk of the RSE effort has focused on the parts of the architecture used for goal-directed execution and control, including the deliberative, habitual, and reexive modules. We specify the capabilities and constraints needed for each module, and discuss how we have extended the current state-of-the-art algorithms so that they can supply the required functionality, such as risk-aware planning in the deliberative module that conforms to mission operator-supplied priorities and constraints. Furthermore, the RSE architecture is modular to enable extension and reconfiguration, as long as the embedded algorithmic components exhibit the required risk-aware behavior in the deliberative module and risk-bounded behavior in the habitual module. To that end, we discuss some feasible, useful RSE configurations and deployments for a Mars rover case and an autonomous underwater vehicle case. We also discuss additional capabilities that the architecture requires to support needed resiliency, such as onboard analysis and learning. © 2016, American Institute of Aeronautics and Astronautics Inc, AIAA.

关键词： NASA

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Risk-aware planning in hybrid domains: An application to autonomous planetary rovers

Risk-aware planning in hybrid domains: An application to aut...

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AIAA Space and Astronautics Forum and Exposition, SPACE 2016

作者： Santana, Pedro Vaqueroy, Tiago Timmonsz, Eric Williams, Brian C. McGhan, Catharine L. R. Murray, Richard M. Toledo, Claudio Department of Aeronautics and Astronautics Massachusetts Institute of Technology 32 Vassar Street 32-224 CambridgeMA02139 United States Computer Science and Artificial Intelligence Laboratory Massachusetts Institute of Technology 32 Vassar Street 32-224 CambridgeMA02139 United States Electrical Engineering & Computer Science Massachusetts Institute of Technology 32 Vassar Street 32-224 CambridgeMA02139 United States Department of Aeronautics and Astronautics Massachusetts Institute of Technology 77 Massachusetts Avenue 33-330 CambridgeMA02139 United States Department of Control and Dynamical Systems California Institute of Technology 1200 E. California Blvd. Mail Code 305-16 PasadenaCA91125 United States Department of Control and Dynamical Systems California Institute of Technology 1200 E. California Blvd. Mail Code 107-81 PasadenaCA91125 United States Instituto de Ciências Matemáticas e de Computacão Avenida Trabalhador São-Carlense 400 AraraquaraSão Paulo Brazil Universidade de São Paulo SP13566-590 Brazil

ISBN: (数字)9781624104275

ISBN: (纸本)9781624104275

Expanding robotic space exploration beyond the immediate vicinity of Earth's orbit can only be achieved by increasingly autonomous agents, given the sometimes insurmountable challenges of teleoperation over great distances. Among the numerous requirements that a fully autonomous robotic space explorer must meet, here we focus on three key mission-enabling technologies: the ability to act under uncertainty and adapt to its environment;the ability to optimize performance while offering hard bounds on the risk of mission failure;and the ability to handle complex hybrid (discrete and continuous) mission planning problems in a provably correct and scalable fashion. In this paper, we show how CLARK, a planner capable of generating risk-bounded, dynamic temporal plans for autonomous agents operating under uncertainty, is able to efficiently generate temporal plans for a challenging planetary rover scenario featuring temporal uncertainty that could not be addressed by previous methods. © 2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Orbits

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A Solvability Condition for Reactive Power Flow

A Solvability Condition for Reactive Power Flow

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IEEE Annual Conference on Decision and control

作者： John W. Simpson-Porco Florian Dorfler Francesco Bullo Department of Mechanical Engineering and the Center for Control Dynamical Systems and Computation University of California Santa Barbara Automatic Control Laboratory ETH Zurich 8092 Zurich Switzerland

ISBN: (纸本)9781479978878

A central question in the analysis and operation of power networks is the feasibility of a unique high-voltage solution to the power flow equations satisfying operational constraints. For planning, monitoring, and contingency analysis in transmission networks, the high-voltage solution of these nonlinear equations can be constructed only numerically or roughly approximated using a linear DC power flow. In this work we analytically study the solvability of the nonlinear decoupled reactive power flow equations, and present a solvability condition relating the existence of a unique high-voltage solution to the spatial distribution of loading and the effective impedances between load buses. We validate the accuracy and applicability of our results through standard power network test cases.

关键词： Reactive power Mathematical model Generators Load modeling Power system stability Loading Numerical stability

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A Risk-Aware Architecture for Resilient Spacecraft Operations

A Risk-Aware Architecture for Resilient Spacecraft Operation...

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IEEE Aerospace Conference

作者： Catharine L. R. McGhan Richard M. Murray Michel D. Ingham Masahiro Ono Tara Estlin Romain Serra Brian C. Williams Department of Control and Dynamical Systems California Institute of Technology Jet Propulsion Laboratory California Institute of Technology Universite de Toulouse LAAS-CNRS Department of Aeronautics and Astronautics Massachusetts Institute of Technology

ISBN: (纸本)9781479953813

In this paper we discuss a resilient, risk-aware software architecture for onboard, real-time autonomous operations that is intended to robustly handle uncertainty in spacecraft behavior within hazardous and unconstrained environments, without unnecessarily increasing complexity. This architecture, the Resilient Spacecraft Executive (RSE), serves three main functions: (1) adapting to component failures to allow graceful degradation, (2) accommodating environments, science observations, and spacecraft capabilities that are not fully known in advance, and (3) making risk-aware decisions without waiting for slow ground-based reactions. This RSE is made up of four main parts: deliberative, habitual, and reflexive layers, and a state estimator that interfaces with all three. We use a risk-aware goal-directed executive within the deliberative layer to perform risk-informed planning, to satisfy the mission goals (specified by mission control) within the specified priorities and constraints. Other state-of-the-art algorithms to be integrated into the RSE include correct-by-construction control synthesis and model-based estimation and diagnosis. We demonstrate the feasibility of the architecture in a simple implementation of the RSE for a simulated Mars rover scenario.

关键词： Space vehicles Computer architecture Resource management Uncertainty Resilience Robustness Complexity theory

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An improvement of the piggyback algorithm for parallel model checking 21

An improvement of the piggyback algorithm for parallel model...

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21st International Symposium on Model Checking of Software, SPIN 2014

作者： Filippidis, Ioannis Holzmann, Gerard J. Control and Dynamical Systems California Institute of Technology PasadenaCA91125 United States Laboratory for Reliable Software Jet Propulsion Laboratory California Institute of Technology PasadenaCA91109 United States

ISBN: (纸本)9781450324526

This paper extends the piggyback algorithm to enlarge the set of liveness properties it can verify. Its extension is motivated by an attempt to express in logic the counterexamples it can detect and relate them to bounded liveness. The original algorithm is based on parallel breadth-first search and piggybacking of accepting states that are deleted after counting a fixed number of transitions. The main improvement is obtained by renewing the counter of transitions when the same accepting states are visited in the negated property automaton. In addition, we describe piggybacking of multiple states in either sets (exact) or Bloom filters (lossy but conservative), and use of local searches that attempt to connect cycles fragmented among processing cores. Finally it is proved that accepting cycle detection is in NC in the size of the product automaton's entire state space, including unreachable states. Copyright 2014 ACM.

关键词： Model checking

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Formal specification and synthesis of mission plans for unmanned aerial vehicles

Formal specification and synthesis of mission plans for unma...

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2014 AAAI Spring Symposium

作者： Humphrey, Laura R. Wolff, Eric M. Topcu, Ufuk Air Force Research Laboratory Control Science Center of Excellence WPAFB Dayton OH 45433 United States Control and Dynamical Systems California Institute of Technology Pasadena CA 91125 United States Electrical and Systems Engineering University of Pennsylvania Philadelphia PA 19104 United States

ISBN: (纸本)9781577356554

As unmanned aerial vehicle (UAV) missions become increasingly complex, automated tools are needed to assist UAV operators in mission planning and execution. Formal methods such as model checking have recently been used for similar purposes, e.g. motion planning for ground robots. Here, we review applications of formal methods to problems in robot control and multi-agent planning and discuss how related techniques can be expanded to serve as the foundation for improved humanautomation UAV intelligence, surveillance, and reconnaissance (ISR) mission planning systems. Copyright © 2014, Association for the Advancement of Artificial Intelligence. All rights reserved.

关键词： Formal specification

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Roadmaps using gradient extremal paths

Roadmaps using gradient extremal paths

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IEEE International Conference on Robotics and Automation (ICRA)

作者： Ioannis Filippidis Kostas J. Kyriakopoulos Control and Dynamical Systems Department California Institute of Technology Pasadena CA USA Control Systems Laboratory Department of Mechanical Engineering National Technical University of Athens Zografou Greece

This work proposes a motion planning method based on the construction of a roadmap connecting the critical points of a potential field or a distance function. It aims to overcome the limitation of potential field methods due to local minima caused by concave obstacles. The roadmap is incrementally constructed by a two-step procedure. Starting from a minimum, adjacent saddle-points are found using a local saddle-point search method. Then, the new saddle-points are connected to the minima by gradient descent. A numerical continuation algorithm from the computational chemistry literature is used to find saddle-points. It traces the valleys of the potential field, which are gradient extremal paths, defined as the points where the gradient is an eigenvector of the Hessian matrix. The definition of gradient bisectors is also discussed. The presentation conclude simulations in cluttered environments.

关键词： Joining processes Prediction algorithms Convergence Navigation Planning Equations Mathematical model

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