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Analysis of Sliding-Mode control systems with Unmatched Disturbances Altering the Relative Degree ⁎

IFAC-PapersOnLine 2020年第2期53卷 5122-5128页

作者： Tobias Posielek Kai Wulff Johann Reger Institute of System Dynamics and Control German Aerospace Center (DLR) Münchner Str. 20 D-82234 Wessling Germany Control Engineering Group Technische Universität Ilmenau P.O. Box 10 05 65 D-98684 Ilmenau Germany

We consider sliding-mode control systems subject to unmatched disturbances. Classical first-order sliding-mode techniques are capable to compensate unmatched disturbances if differentiations of the output of sufficiently high order are included in the sliding variable. For such disturbances it is commonly assumed that they do not affect the relative degree of the system. In this contribution we consider disturbances that alter the relative degree of the process and study their impact on the closed-loop control system with the classical first-order sliding-mode design. We analyse the reaching and sliding phase of the resulting closed-loop system. We show that uniqueness of the solution may be lost and derive conditions for such behaviour. We present conditions for the stability of the sliding-mode dynamics and analyse the disturbance rejection properties. A simulation case study of a two-mass spring-damper system illustrates the various closed-loop behaviours.

关键词： Sliding-mode control Unmatched disturbances Relative degree

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On a solution to a nonlinear heat transfer model by the BEM

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AIP Conference Proceedings 2023年第1期2624卷

作者： A. L. Kazakov L. F. Spevak Matrosov Institute for System Dynamics and Control Theory Siberian Branch of the Russian Academy of Sciences Irkutsk Russia Irkutsk State Transport University Irkutsk Russia Ural State University of Railway Transport Ekaterinburg Russia Institute of Engineering Science Ural Branch of the Russian Academy of Sciences Ekaterinburg Russia

The paper deals with a nonlinear heat transfer model based on the nonlinear second order degenerate parabolic equation with arbitrary form of nonlinearity. Boundary value problems with two non-stationary boundary conditions are discussed: the problem with a specified heat wave front and the problem with a condition specifying the desired function at some manifold. A new existence theorem is formulated. Time-step algorithms based on the boundary element method and the dual reciprocity method are developed. Iteration procedures converging to the continuous solution on each time step are proposed. The algorithms are verified by comparison with known exact solution.

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The importance of horizontal Poynting flux in the solar photosphere

arXiv

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arXiv 2022年

作者： Silva, Suzana S.A. Murabito, Mariarita Jafarzadeh, Shahin Stangliani, Marco Verth, Gary Ballai, Istvan Fedun, Viktor Plasma Dynamics Group Department of Automatic Control and Systems Engineering University of Sheffield Sheffield United Kingdom Department of Physics Aeronautics Institute of Technology São José dos Campos Brazil INAF - Osservatorio Astronomico di Roma Via Frascati33 Monte Porzio Catone RM 00078 Italy Max Planck Institute for Solar System Research Justus-von-Liebig-Weg 3 Göttingen37077 Germany Rosseland Centre for Solar Physics University of Oslo P.O. Box 1029 Blindern OsloNO-0315 Norway ASI Italian Space Agency Via del Politecnico snc Rome00133 Italy Plasma Dynamics Group School of Mathematics and Statistics University of Sheffield Sheffield United Kingdom

The electromagnetic energy flux in the lower atmosphere of the Sun is a key tool to describe the energy balance of the solar atmosphere. Current investigations on energy flux in the solar atmosphere focus primarily on the vertical electromagnetic flux through the photosphere, ignoring the Poynting flux in other directions and its possible contributions to local heating. Based on a realistic Bifrost simulation of a quiet-Sun (coronal hole) atmosphere, we find that the total electromagnetic energy flux in the photosphere occurs mainly parallel to the photosphere, concentrating in small regions along intergranular lanes. Thereby, it was possible to define a proxy for this energy flux based on only variables that can be promptly retrieved from observations, namely, horizontal velocities of the small-scale magnetic elements and their longitudinal magnetic flux. Our proxy accurately describes the actual Poynting flux distribution in the simulations, with the electromagnetic energy flux reaching 1010 erg cm−2 s−1. To validate our findings, we extended the analysis to SUNRISE/IMaX data. First, we show that Bifrost realistically describes photospheric quiet-Sun regions, as the simulation presents similar distributions for line-of-sight magnetic flux and horizontal velocity field. Second, we found very similar horizontal Poynting flux proxy distributions for the simulated photosphere and observational data. Our results also indicate that the horizontal Poynting flux in the observations is considerably larger than the vertical electromagnetic flux from previous observational estimates. Therefore, our analysis confirms that the electromagnetic energy flux in the photosphere is mainly horizontal and is most intense in localized regions along intergranular lanes. Copyright © 2022, The Authors. All rights reserved.

关键词： Magnetohydrodynamics

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Unexpected frequency of horizontal oscillations of magnetic structures in the solar photosphere

arXiv

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arXiv 2024年

作者： Berretti, M. Stangalini, M. Verth, G. Jafarzadeh, S. Jess, D.B. Berrilli, F. Grant, S.D.T. Duckenfield, T. Fedun, V. University of Trento Via Calepina 14 Trento38122 Italy University of Rome Tor Vergata Department of Physics Via della Ricerca Scientifica 3 Rome00133 Italy ASI Italian Space Agency Via del Politecnico snc Rome00133 Italy Plasma Dynamics Group School of Mathematics and Statistics The University of Sheffield Hicks Building Hounsfield Road SheffieldS3 7RH United Kingdom Max Planck Institute for Solar System Research Justus-von-Liebig-Weg 3 Göttingen37077 Germany Niels Bohr International Academy Niels Bohr Institute Blegdamsvej 17 CopenhagenDK-2100 Denmark Astrophysics Research Centre School of Mathematics and Physics Queen’s University Belfast Northern Ireland BelfastBT7 1NN United Kingdom Department of Physics and Astronomy California State University Northridge NorthridgeCA91330 United States Plasma Dynamics Group Department of Automatic Control and Systems Engineering The University of Sheffield Mappin Street SheffieldS1 3JD United Kingdom

It is well known that the dominant frequency of oscillations in the solar photosphere is ≈3 mHz, which is the result of global resonant modes pertaining to the whole stellar structure. However, analyses of the horizontal motions of nearly 1 million photospheric magnetic elements spanning the entirety of solar cycle 24 have revealed an unexpected dominant frequency, ≈5 mHz, a frequency typically synonymous with the chromosphere. Given the distinctly different physical properties of the magnetic elements examined in our statistical sample, when compared to largely quiescent solar plasma where ≈3 mHz frequencies are omnipresent, we argue that the dominant ≈5 mHz frequency is not caused by the buffeting of magnetic elements, but instead is due to the nature of the underlying oscillatory driver itself. This novel result was obtained by exploiting the unmatched spatial and temporal coverage of magnetograms acquired by the Helioseismic and Magnetic Imager (HMI) on board NASA’s Solar dynamics Observatory (SDO). Our findings provide a timely avenue for future exploration of the magnetic connectivity between sub-photospheric, photospheric, and chromospheric layers of the Sun’s dynamic atmosphere. Copyright © 2024, The Authors. All rights reserved.

关键词： Magnetic structure

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Hierarchical control of a Quadcopter under Stuck Actuator Fault

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IFAC-PapersOnLine 2020年第2期53卷 4258-4263页

作者： Ngoc Thinh Nguyen Ionela Prodan Felix Petzke Stefan Streif Laurent Lefèvre Univ. of Luebeck Institute for Robotics and Cognitive Systems 23562 Luebeck Germany Univ. Grenoble Alpes Grenoble INP Institute of Engineering and Management Univ. Grenoble Alpes. LCIS Valence France Technische Universität Chemnitz Automatic Control and System Dynamics (ACSD) Lab 09107 Chemnitz Germany

We propose a hierarchical FTC (Fault Tolerant control) scheme for trajectory tracking by a quadcopter system under stuck actuator fault and actuator saturation. Both the FDI (Fault Detection and Isolation) and control reconfiguration modules are implemented at the low-level associated with the rotation dynamics through a NMPC (Nonlinear Model Predictive control) strategy. The uncontrolled (when under fault) yaw torque is predicted and compensated by the NMPC. It is shown that the overall control scheme succeeds in maintaining trajectory tracking for various fault events (both in the sense of having various stuck values and in the sense of changing the actuator under fault).

关键词： FTC Stuck actuator fault Trajectory tracking Hierarchical control Feedback linearization NMPC Quadcopter

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Application of a case-based approach for tasks of industrial safety inspection 2

Application of a case-based approach for tasks of industrial...

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2nd Scientific-Practical Workshop Information Technologies: Algorithms, Models, systems, ITAMS 2019

作者： Yurin, Aleksandr Yu. Berman, Aleksandr F. Nikolaychuk, Olga A. Kuznetsov, Kirill A. Matrosov Institute for System Dynamics and Control Theory Siberian Branch of the Russian Academy of Sciences 134 Lermontov st. Irkutsk664033 Russia Irkutsk Research and Design Institute of Chemical and Petrochemical Engineering 3 Akademika Kurchatova st. Irkutsk664074 Russia

A regular assessment of a technical state and calculation of a residual life are important measures for the safe operation of petrochemical facilities. These measures are parts of the industrial safety inspection (ISI) procedure. The efficiency of this procedure can be improved with the aid of decision support systems, which are process and reuse of accumulated information and experience on the basis of a case-based reasoning (CBR) approach. The formalization of the main ISI tasks is made in order to apply CBR. The case models developed for each ISI task. Testing models and approach was carried out in the special software in Irkutsk research and design institute of chemical and petroleum engineering. Copyright © 2019 for this paper by its authors.

关键词： Case based reasoning

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The InSight-HP3 mole on Mars: Lessons learned from attempts to penetrate to depth in the Martian soil

arXiv

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arXiv 2021年

作者： Spohn, Tilman Hudson, Troy L. Witte, Lars Wippermann, Torben Wisniewski, Lukasz Kedziora, Bartosz Vrettos, Christos Lorenz, Ralph D. Golombek, Matthew Lichtenheldt, Roy Grott, Matthias Knollenberg, Jörg Krause, Christian Fantinati, Cinzia Nagihara, Seiichi Grygorczuk, Jurek International Space Science Institute Bern Switzerland DLR Institute of Planetary Research Berlin Germany Jet Propulsion Laboratory California Institute of Technology Pasadena United States DLR Institute of Space Systems Bremen Germany Astronika Warsaw Poland Department of Civil Engineering University of Kaiserslautern Kaiserslautern Germany Johns Hopkins Applied Physics Laboratory LaurelMD20723 United States DLR Institute of System Dynamics and Control Oberpfaffenhofen Germany DLR Microgravity User Support Center Cologne Germany Department of Geosciences Texas Tech University Lubbock United States

The NASA InSight lander mission to Mars payload includes the Heat Flow and Physical Properties Package HP3 to measure the surface heat flow. The package was designed use a small penetrator - nicknamed the mole - to implement a vertical string of temperature sensors in the soil to a depth of 5 m. The mole itself is equipped with sensors to measure a thermal conductivity- depth profile as it proceeds to depth. The heat flow would be calculated from the product of the temperature gradient and the thermal conductivity. To avoid the perturbation caused by annual surface temperature variations, the measurements would be taken at a depth between 3 m and 5 m. The mole had been designed to penetrate cohesionless soil similar in rheology to Quartz sand which was expected to provide a good analogue material for Martian sand. The sand would provide friction to the buried mole hull to balance the remaining recoil of the mole hammer mechanism that drives the mole forward. Unfortunately, the mole did not penetrate more than roughly a mole length of 40 cm. The failure to penetrate deeper was largely due to a cohesive duricrust of a few tens of centimeter thickness that failed to provide the required friction. Although a suppressor mass and spring as part of the mole hammer mechanism absorbed much of the recoil, the available mass did not allow designing a system that would have eliminated the recoil. The mole penetrated to 40 cm depth benefiting from friction provided by springs in the support structure from which it was deployed. It was found in addition that the Martian soil provided unexpected levels of penetration resistance that would have motivated to designing a more powerful mole. The low weight of the moIe support structure was not enough to guide the mole penetrating vertically. It is concluded that more mass would have allowed to design a more robust system with little or no recoil, more energy of the mole hammer mechanism and a more massive support structure. In additio

关键词： Friction

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Model Predictive Power Allocation for Hybrid Battery Balancing systems

Model Predictive Power Allocation for Hybrid Battery Balanci...

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IEEE Conference on Vehicle Power and Propulsion (VPPC)

作者： Ricardo de Castro Rui Esteves Araujo Institute of System Dynamics and Control German Aerospace Center (DLR) Germany Faculty of Engineering University of Porto Porto Portugal

This work focuses on hybrid balancing systems, a recently-proposed concept that enables balancing of battery cells and hybridization with supercapacitors. To control this system, a model predictive control framework is developed. In addition to distributing the supercapacitor power among the balancing circuits, this framework is also able to minimize state-of-charge and thermal imbalances in the battery cells, as well as energy losses in the balancing circuits. The effectiveness of the proposed approach is verified via numerical simulations. It is shown that, in comparison with state-of-art balancing solutions, the proposed control approach is able to decrease battery stress in up to 9% and the maximum temperature in up to 4.5%.

关键词： Batteries Supercapacitors Resource management Integrated circuit modeling Energy loss Energy management

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On an exact solution to the nonlinear heat equation with a source

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Journal of Physics: Conference Series 2021年第1期1847卷

作者： A L Kazakov A A Lempert L F Spevak Matrosov Institute for system dynamics and control theory SB RAS 134 Lermontov str. 664033 Irkutsk Russia Institute of Engineering Science UB RAS 34 Komsomolskaya str. 620049 Ekaterinburg Russia

The paper is devoted to the study of a singular nonlinear second-order parabolic equation, which is called the porous medium equation or the nonlinear heat equation. One of the important classes of its solutions is heat waves propagating over a zero background with a finite velocity. This property is not typical for parabolic equations and is a consequence of singularity. The main object of study is exact solutions of mentioned type. A new way of separating variables is used to represent them. We obtain conditions when it is possible to make a reduction to the Cauchy problem for an ordinary second-order differential equation with a singularity. It is shown that the Cauchy problem describes a heat wave whose front moves exponentially. We construct a solution to the Cauchy problem as a power series and determine the cases when the series breaks off, i.e. the solution has the form of a polynomial, and the corresponding heat wave can be written explicitly. If the Cauchy problem cannot be explicitly integrated, the solution is constructed numerically. An algorithm based on the boundary element method is proposed. We perform a computational experiment and conclude the properties of the found solutions. Besides, the accuracy of the calculation results is analyzed.

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Observer design for a railway running gear with independently rotating wheels

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IFAC-PapersOnLine 2019年第15期52卷 325-330页

作者： Alexander Keck Christoph Schwarz Thomas Meurer Institute of System Dynamics and Control German Aerospace Center Münchener Str. 20 82234 Oberpfaffenhofen-Wessling Germany Chair of Automatic Control Faculty of Engineering Kiel University Kaiserstraße 2 24143 Kiel Germany

The German Aerospace Center bundles its railway research in the long-term project “Next Generation Train” (NGT). The NGT is a high speed train concept in light-weight design and double-deck configuration. To reduce wheel and rail wear and to enhance the passenger capacity, a mechatronic running gear with independently rotating wheels (IRW) is designed. This configuration requires an advanced control of the lateral dynamics in order to fully exploit the potential in minimizing wear and noise. In terms of a model-based control design, the controller performance highly depends on the estimated lateral position of the running gear relative to the track. In a practical environment it is difficult to directly measure this displacement of the wheel-pair. Therefore this article deals with the question which sensor configuration enables an appropriate estimation of the lateral displacement and is suitable for observer design. Hence, an observability analysis and an observer synthesis to estimate the lateral position for the nonlinear system of the 1:5 scaled hardware running gear is carried out. For validation purposes three estimators are implemented at the real-time environment of the testbed and the estimation errors of the observer configurations are compared.

关键词： Nonlinearity Observability Observers Extended Kalman filters Railways

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