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Pyragas-type feedback control for chatter mitigation in high-speed milling

IFAC-PapersOnLine 2015年第12期48卷 334-339页

作者： Van De Wouw, N. Van Dijk, N.J.M. Nijmeijer, H. Department Mechanical Engineering Eindhoven University of Technology Eindhoven Netherlands Philips Innovation Services Eindhoven Netherlands Department of Civil Environmental and Geo- Engineering University of Minnesota Minneapolis United States Delft Center for Systems and Control Delft University of Technology Delft Netherlands

Chatter is an instability phenomenon in high-speed milling that limits machining productivity by the induction of tool vibrations. In this paper, a design methodology for loworder Pyragas-type delayed feedback controllers is proposed. These controllers enable dedicated shaping of the chatter stability boundary such that working points of higher machining productivity become feasible while avoiding chatter. The control design problem is cast into a nonsmooth optimization problem, which is solved using bundle methods. Distinct benefits of this approach are the a priori fixing of the controller order, the limitation of the control action, and the fact that no finite-dimensional model approximations and online chatter estimation techniques are required. A representative example illustrates the merit of the proposed methodology in terms of increasing the chatter-free depth of cut, thereby enabling significant increases in the productivity of milling processes. © 2015, IFAC (International Federation of Automatic control) Hosting by Elsevier Ltd. All rights reserved.

关键词： Robust control

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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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Suboptimal Stabilizing controllers for Linearly Solvable System

Suboptimal Stabilizing Controllers for Linearly Solvable Sys...

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IEEE Annual Conference on Decision and control

作者： Yoke Peng Leong Matanya B. Horowitz Joel W. Burdick Control and Dynamical Systems California Institute of Technology Pasadena CA 91125 USA Mechanical Engineering California Institute of Technology Pasadena CA 91125 USA

ISBN: (纸本)9781479978878

This paper presents a novel method to synthesize stochastic control Lyapunov functions for a class of nonlinear, stochastic control systems. In this work, the classical nonlinear Hamilton-Jacobi-Bellman partial differential equation is transformed into a linear partial differential equation for a class of systems with a particular constraint on the stochastic disturbance. It is shown that this linear partial differential equation can be relaxed to a linear differential inclusion, allowing for approximating polynomial solutions to be generated using sum of squares programming. It is shown that the resulting solutions are stochastic control Lyapunov functions with a number of compelling properties. In particular, a-priori bounds on trajectory suboptimality are shown for these approximate value functions. The result is a technique whereby approximate solutions may be computed with non-increasing error via a hierarchy of semidefinite optimization problems.

关键词： Linear partial differential equation Stochastic control systems stochastic disturbance Liapunov function controllers Soluble

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Accelerating tube-based model predictive control by constraint removal

Accelerating tube-based model predictive control by constrai...

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IEEE Annual Conference on Decision and control

作者： Michael Jost Gabriele Pannocchia Martin Monnigmann Automatic Control and Systems Theory Department of Mechanical Engineering Ruhr-Universitat Bochum Germany Department of Civil and Industrial Engineering University of Pisa Italy

ISBN: (纸本)9781479978878

Tube-based model predictive control (MPC) is a variant of MPC that is suitable for constrained linear systems subject to additive bounded disturbances. We extend constraint removal, a technique recently introduced to accelerate nominal MPC, to tube-based MPC. Constraint removal detects inactive constraints before actually solving the MPC problem. By removing constraints that are known to be inactive from the optimization problem, the computational time required to solve it can be reduced considerably. We show that the number of constraints to be considered in the optimization problem decreases along any trajectory of the closed-loop system, until only the unconstrained optimization problem remains. The proposed variant of constraint removal is easy to apply. Since it does not depend on details of the optimization algorithm, it can easily be added to existing implementations of tube-based MPC.

关键词： Optimization algorithms Constraint Model predictive control Predictive control Linear system acceleration Closed loop systems trajectory

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Real-time Pricing and Distributed Decision Makings Leading to Optimal Power Flow of Power Grids

Real-time Pricing and Distributed Decision Makings Leading t...

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American control Conference

作者： Kenji Hirata Joao P. Hespanha Kenko Uchida Department of Mechanical Engineering Nagaoka University of Technology Nagaoka 940 2188 Japan Center for Control Dynamical Systems and Computation and the Department of Electrical and Computer Engineering University of California Santa Barbara CA 93106 USA Department of Electrical Engineering and Bioscience Waseda University Tokyo 169 8555 Japan

ISBN: (纸本)9781479917730

Motivated by distributed control problems of power supply/demand networks, this paper investigates application case studies of the real-time pricing and distributed decision makings methodology. We consider the optimal power flow problem with the DC power flow model, and the New England 39-bus test system is used. Stability of the resulting price based control system is analyzed with consideration for specific structures of the power flow problem. The resulting simulation studies illustrate the efficiency of the proposed method and validate the stability analysis procedure.

关键词： optimal load flow Power grids Power flow distributed decision making Pricing decentralised control Test systems DC load flow

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Localization of disturbances in transportation systems

Localization of disturbances in transportation systems

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IEEE Annual Conference on Decision and control

作者： Sivaranjani S Yuh-Shyang Wang Vijay Gupta Ketan Savla Department of Electrical Engineering University of Notre Dame Notre Dame IN USA department of Control and Dynamical Systems California Institute of Technology Pasadena CA 91125 USA Sonny Astani Department of Civil and Environmental Engineering University of Southern California Los Angeles CA 90089-2531 USA

ISBN: (纸本)9781479978878

We present a control strategy for localization and attenuation of disturbances in transportation systems. Sudden and large disturbances in a transportation network can lead to the creation and propagation of shock waves which spread throughout the system causing jams and decreasing system throughput. By considering the Cell Transmission Model of traffic flow, we design a minimum-energy controller that exploits inter-vehicle communication to localize shock waves to small sections of the highway and attenuate them within a specified period of time. The control design is illustrated through simulations on realistic data from the I-210 highway in California.

关键词： transport system Transport networks Freeway control strategy design control time periods Vehicle to vehicle communications Traffic models

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Autonomy and Machine Intelligence in Complex systems: A Tutorial

Autonomy and Machine Intelligence in Complex Systems: A Tuto...

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American control Conference

作者： Kyriakos G. Vamvoudakis Panos J. Antsaklis Warren E. Dixon Joao P. Hespanha Frank L. Lewis Hamidreza Modares Bahare Kiumarsi Center for Control Dynamical-systems and Computation (CCDC) University of California Santa Barbara CA 93106-9560 USA Electrical Engineering Department University of Notre Dame Notre Dame IN 46556 USA Department of Mechanical and Aerospace Engineering University of Florida Gainesville FL 32611 USA The University of Texas at Arlington Research Institute (UTARI) Ft. Worth TX 76118 USA

ISBN: (纸本)9781479917730

This tutorial paper will discuss the development of novel state-of-the-art control approaches and theory for complex systems based on machine intelligence in order to enable full autonomy. Given the presence of modeling uncertainties, the unavailability of the model, the possibility of cooperative/non-cooperative goals and malicious attacks compromising the security of teams of complex systems, there is a need for approaches that respond to situations not programmed or anticipated in design. Unfortunately, existing schemes for complex systems do not take into account recent advances of machine intelligence. We shall discuss on how to be inspired by the human brain and combine interdisciplinary ideas from different fields, i.e. computational intelligence, game theory, control theory, and information theory to develop new self-configuring algorithms for decision and control given the unavailability of model, the presence of enemy components and the possibility of network attacks. Due to the adaptive nature of the algorithms, the complex systems will be capable of breaking or splitting into parts that are themselves autonomous and resilient. The algorithms discussed will be characterized by strong abilities of learning and adaptivity. As a result, the complex systems will be fully autonomous, and tolerant to communication failures.

关键词： Machine Learning Complex systems Autonomy Information Theory

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Assessing the speed-up achievable by online constraint removal in MPC

Assessing the speed-up achievable by online constraint remov...

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European control Conference

作者： Michael Jost Gabriele Pannocchia Martin Monnigmann Automatic Control and Systems Theory Department of Mechanical Engineering Ruhr-Universitat Bochum Department of Civil and Industrial Engineering University of Pisa

ISBN: (纸本)9781467371605

We recently proposed to accelerate online MPC calculations by detecting and removing inactive constraints from the online optimization problems as a function of the current initial state. A number of variants of constraint removal (CR) have been explored, ranging from detecting inactive constraints based on precomputed regions of activity or approximations thereof to online methods that do not require any offline preparation. In typical applications CR can reduce the computing times required for the calculation of the model predictive control laws by 15% to 90%. Since CR is very easy to implement, does not require any additional assumptions to be fulfilled beyond the usual ones for stability, and can be combined with all optimization algorithms, it is very easy to cash in the described acceleration. Moreover, CR may prove useful if an existing, established MPC implementation needs to be accelerated, e.g., in order to use it on an embedded processor, but replacing it altogether is not an option.

关键词： Cost function Approximation methods Optimal control Acceleration Runtime Closed loop systems

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Acquisition and Analysis of Dynamic Responses of a Historic Pedestrian Bridge using Video Image Processing

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Journal of Physics: Conference Series 2015年第1期628卷

作者： Michael O'Byrne Bidisha Ghosh Franck Schoefs Deirdre O'Donnell Robert Wright Vikram Pakrashi Department of Civil Structural and Environmental Engineering Trinity College Dublin Ireland LUNAM Université Université de Nantes-Ecole Centrale de Nantes CNRS GeM Institute for Research in Civil and Mechanical Engineering University of Nantes Nantes France Dynamical Systems and Risk Laboratory Civil and Environmental Engineering School of Engineering University College Cork Ireland and IXEAD/CAPACITES Society Nantes France1Dynamical Systems and Risk Laboratory Civil and Environmental Engineering School of Engineering University College Cork Ireland

Video based tracking is capable of analysing bridge vibrations that are characterised by large amplitudes and low frequencies. This paper presents the use of video images and associated image processing techniques to obtain the dynamic response of a pedestrian suspension bridge in Cork, Ireland. This historic structure is one of the four suspension bridges in Ireland and is notable for its dynamic nature. A video camera is mounted on the river-bank and the dynamic responses of the bridge have been measured from the video images. The dynamic response is assessed without the need of a reflector on the bridge and in the presence of various forms of luminous complexities in the video image scenes. Vertical deformations of the bridge were measured in this regard. The video image tracking for the measurement of dynamic responses of the bridge were based on correlating patches in time-lagged scenes in video images and utilisinga zero mean normalised cross correlation (ZNCC) metric. The bridge was excited by designed pedestrian movement and by individual cyclists traversing the bridge. The time series data of dynamic displacement responses of the bridge were analysedto obtain the frequency domain response. Frequencies obtained from video analysis were checked against accelerometer data from the bridge obtained while carrying out the same set of experiments used for video image based recognition.

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controllability Metrics, Limitations and Algorithms for Complex Networks

Controllability Metrics, Limitations and Algorithms for Comp...

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American control Conference

作者： Fabio Pasqualetti Sandro Zampieri Francesco Bullo Mechanical Engineering Department University of California at Riverside Department of Information Engineering University of Padova Italy Mechanical Engineering Department and the Center for Control Dynamical Systems and Computation University of California at Santa Barbara

ISBN: (纸本)9781479932757

This paper studies the problem of controlling stable and symmetric complex networks, that is, the joint problem of selecting a set of control nodes and of designing a control input to drive a network to a target state. We adopt the smallest eigenvalue of the controllability Gramian as metric for the controllability degree of a network, as it identifies the energy needed to accomplish the control task. In the first part of the paper we characterize tradeoffs between the control energy and the number of control nodes, based on the network topology and weights. Our bounds show for instance that, if the number of control nodes is constant, then the control energy increases exponentially with the number of network nodes. Consequently, despite the classic controllability notion, few nodes cannot in practice arbitrarily symmetric control complex networks. In the second part of the paper we propose a distributed open-loop strategy with performance guarantees for the control of complex networks. In our strategy we select control nodes based on network partitioning, and we design the control input based on optimal and distributed control techniques. For our control strategy we show that the control energy depends on the controllability properties of the clusters and on their coupling strength, and it is independent of the network dimension.

关键词： Power control complex networks controllability control node control input Ganglia control task network node Network topology

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