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Documents authored by Auer, Ekaterina

Document
DOI: 10.4230/DagSemProc.09471.3
Interval Approaches to Reliable Control of Dynamical Systems

Authors: Andreas Rauh and Ekaterina Auer

Published in: Dagstuhl Seminar Proceedings, Volume 9471, Computer-assisted proofs - tools, methods and applications (2010)

Abstract
Recently, we presented an implementation of interval-based algorithms which can be applied in real-time to control dynamical processes and to estimate internal states and disturbances. The approach is based on verified methods for sets of algebraic equations, ordinary differential equations as well as differential-algebraic equations. Due to this fact, the same program code can be used for two different tasks. On the one hand, we can use it online to estimate non-measurable internal system states which are necessary for nonlinear model-based control strategies. On the other hand, we can verify the admissibility and feasibility of these control strategies offline. Although we use the same code for the online and offline tasks, there is an important difference between them. While the computing time is of minor importance in offline applications, we have to guarantee that the necessary online computations are completed successfully in a predefined time interval. For that reason, the role of verification is slightly different depending on the task. In offline applications, our goal is to compute tightest possible bounds for the sets of all solutions to the control problem under consideration. In contrast to that, we restrict the online mode to a search for a single solution that matches all demands on feasibility of control inputs and admissibility of the trajectories of the state variables in a reliable way. To highlight the practical applicability of the underlying computational routines, we present the following cases for the use of verified solvers in real-time [1-3]. Case 1: Direct computation of feedforward control strategies with the help of differential-algebraic equation solvers. In this application, both verified and non-verified solvers can be used to determine open-loop control strategies for a dynamical system such that its output coincides with a predefined time response within given tolerances. This procedure corresponds to a numerical inversion of the dynamics of the system to be controlled. In this case, verified solvers are used to prove the existence of a control law within given physical bounds for the admissible range of the system inputs. Case 2: If measured data and their time derivatives are available, the same procedures as in case 1 can be used to estimate non-measured state variables as well as non-measurable disturbances. Since the verified algorithms used in this context are capable of propagating bounded measurement uncertainties, the quality of the state and disturbance estimates can be expressed in terms of the resulting interval widths. Moreover, assumptions about the parameters and the structure of the underlying model can be verified. Case 3: Routines for verified sensitivity analysis provide further information on the influence of variations of control inputs on the trajectories of the state variables. We present novel procedures implementing a sensitivity-based framework for model-predictive control. These procedures can be integrated directly in a feedback control structure. Sometimes it is necessary to combine verified and non-verified algorithms to solve a given control problem. In this case, it is important to certify the results of the algorithm appropriately. Based on the four-tier hierarchy presented in earlier works [4], we develop a measure for characterizing such mixed approaches. The presentation is concluded with simulation and experimental results for the example of temperature control of a distributed heating system. [1] Rauh, Andreas; Auer, Ekaterina: Applications of Verified DAE Solvers in Engineering, Intl. Workshop on Verified Computations and Related Topics, COE Lecture Note Vol. 15: Kyushu University, pp. 88-96, Karlsruhe, Germany, 2009. [2] Rauh, Andreas; Menn, Ingolf; Aschemann, Harald: Robust Control with State and Disturbance Estimation for Distributed Parameter Systems, Proc. of 15th Intl. Workshop on Dynamics and Control 2009, pp. 135-142, Tossa de Mar, Spain, 2009. [3] Rauh, Andreas; Auer, Ekaterina; Aschemann, Harald: Real-Time Application of Interval Methods for Robust Control of Dynamical Systems, CD-Proc. of IEEE Intl. Conference on Methods and Models in Automation and Robotics MMAR 2009, Miedzyzdroje, Poland, 2009. [4] Auer, Ekaterina; Luther, Wolfram: Numerical Verification Assessment in Computational Biomechanics, in A. Cuyt, W. Krämer, W. Luther, P. Markstein: Numerical Validation in Current Hardware Architectures, LNCS 5492, pp. 145-160, Springer-Verlag, Berlin, Heidelberg, 2009.
Cite as

Andreas Rauh and Ekaterina Auer. Interval Approaches to Reliable Control of Dynamical Systems. In Computer-assisted proofs - tools, methods and applications. Dagstuhl Seminar Proceedings, Volume 9471, pp. 1-28, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)

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@InProceedings{rauh_et_al:DagSemProc.09471.3,
  author =	{Rauh, Andreas and Auer, Ekaterina},
  title =	{{Interval Approaches to Reliable Control of Dynamical Systems}},
  booktitle =	{Computer-assisted proofs - tools, methods and applications},
  pages =	{1--28},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2010},
  volume =	{9471},
  editor =	{B. Malcolm Brown and Erich Kaltofen and Shin'ichi Oishi and Siegfried M. Rump},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.09471.3},
  URN =		{urn:nbn:de:0030-drops-25120},
  doi =		{10.4230/DagSemProc.09471.3},
  annote =	{Keywords: Robust control, Ordinary differential equations, Differential-algebraic equations}
}
Document
DOI: 10.4230/DagSemProc.09471.4
Verification and Validation for Femur Prosthesis Surgery

Authors: Ekaterina Auer, Roger Cuypers, Eva Dyllong, Stefan Kiel, and Wolfram Luther

Published in: Dagstuhl Seminar Proceedings, Volume 9471, Computer-assisted proofs - tools, methods and applications (2010)

Abstract
In this paper, we describe how verified methods we are developing in the course of the project TellHim&S (Interval Based Methods For Adaptive Hierarchical Models In Modeling And Simulation Systems) can be applied in the context of the biomechanical project PROREOP (Development of a new prognosis system to optimize patient-specific pre- operative surgical planning for the human skeletal system). On the one hand, it includes the use of verified hierarchical structures for reliable geometric modeling, object decomposition, distance computation and path planning. On the other hand, we cover such tasks as verification and validation assessment and propagation of differently described uncertainties through system models in engineering or mechanics.
Cite as

Ekaterina Auer, Roger Cuypers, Eva Dyllong, Stefan Kiel, and Wolfram Luther. Verification and Validation for Femur Prosthesis Surgery. In Computer-assisted proofs - tools, methods and applications. Dagstuhl Seminar Proceedings, Volume 9471, pp. 1-22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)

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@InProceedings{auer_et_al:DagSemProc.09471.4,
  author =	{Auer, Ekaterina and Cuypers, Roger and Dyllong, Eva and Kiel, Stefan and Luther, Wolfram},
  title =	{{Verification and Validation for Femur Prosthesis Surgery}},
  booktitle =	{Computer-assisted proofs - tools, methods and applications},
  pages =	{1--22},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2010},
  volume =	{9471},
  editor =	{B. Malcolm Brown and Erich Kaltofen and Shin'ichi Oishi and Siegfried M. Rump},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.09471.4},
  URN =		{urn:nbn:de:0030-drops-25133},
  doi =		{10.4230/DagSemProc.09471.4},
  annote =	{Keywords: Graphical interface construction, superquadrics, 3D modeling, biomedical engineering}
}
Document
DOI: 10.4230/DagSemProc.08021.15
Numerical Verification Assessment in Computational Biomechanics

Authors: Ekaterina Auer and Wolfram Luther

Published in: Dagstuhl Seminar Proceedings, Volume 8021, Numerical Validation in Current Hardware Architectures (2008)

Abstract
In this paper, we present several aspects of the recent project PROREOP, in which a new prognosis system is developed for optimizing patient-specific preoperative surgical planning for the human skeletal system. We address verification and validation assessment in PROREOP with special emphasis on numerical accuracy and performance. To assess numerical accuracy, we propose to employ graded instruments, including accuracy tests and error analysis. The use of such instruments is exemplified for the process of accurate femur reconstruction. Moreover, we show how to verify the simulation results and take into account measurement uncertainties for a part of this process using tools and techniques developed in the project TellHIM&S.
Cite as

Ekaterina Auer and Wolfram Luther. Numerical Verification Assessment in Computational Biomechanics. In Numerical Validation in Current Hardware Architectures. Dagstuhl Seminar Proceedings, Volume 8021, pp. 1-15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)

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@InProceedings{auer_et_al:DagSemProc.08021.15,
  author =	{Auer, Ekaterina and Luther, Wolfram},
  title =	{{Numerical Verification Assessment in Computational Biomechanics}},
  booktitle =	{Numerical Validation in Current Hardware Architectures},
  pages =	{1--15},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2008},
  volume =	{8021},
  editor =	{Annie Cuyt and Walter Kr\"{a}mer and Wolfram Luther and Peter Markstein},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.08021.15},
  URN =		{urn:nbn:de:0030-drops-14374},
  doi =		{10.4230/DagSemProc.08021.15},
  annote =	{Keywords: Numerical verification assessment, validation, uncertainty, result verification}
}
Document
DOI: 10.4230/DagSemProc.05391.5
Integration of reliable algorithms into modeling software

Authors: Wolfram Luther, Gerhard Haßlinger, Ekaterina Auer, Eva Dyllong, Daniela Traczinski, and Holger Traczinski

Published in: Dagstuhl Seminar Proceedings, Volume 5391, Algebraic and Numerical Algorithms and Computer-assisted Proofs (2006)

Abstract
In this note we discuss strategies that would enhance modern modeling and simulation software (MSS) with reliable routines using validated data types, controlled rounding, algorithmic differentiation and interval equation or initial value problem solver. Several target systems are highlighted. In stochastic traffic modeling, the computation of workload distributions plays a prominent role since they influence the quality of service parameters. INoWaTIV is a workload analysis tool that uses two different techniques: the polynomial factorization approach and the Wiener-Hopf factorization to determine the work-load distributions of GI/GI/1 and SMP/GI/1 service systems accurately. Two extensions of a multibody modeling and simulation software were developed to model kinematic and dynamic properties of multibody systems in a validated way. Furthermore, an interface was created that allows the computation of convex hulls and reliable lower bounds for the distances between subpav-ing-encoded objects constructed with SIVIA (Set Inverter Via Interval Analysis).
Cite as

Wolfram Luther, Gerhard Haßlinger, Ekaterina Auer, Eva Dyllong, Daniela Traczinski, and Holger Traczinski. Integration of reliable algorithms into modeling software. In Algebraic and Numerical Algorithms and Computer-assisted Proofs. Dagstuhl Seminar Proceedings, Volume 5391, pp. 1-17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)

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@InProceedings{luther_et_al:DagSemProc.05391.5,
  author =	{Luther, Wolfram and Ha{\ss}linger, Gerhard and Auer, Ekaterina and Dyllong, Eva and Traczinski, Daniela and Traczinski, Holger},
  title =	{{Integration of reliable algorithms into modeling software}},
  booktitle =	{Algebraic and Numerical Algorithms and Computer-assisted Proofs},
  pages =	{1--17},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{5391},
  editor =	{Bruno Buchberger and Shin'ichi Oishi and Michael Plum and Sigfried M. Rump},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.05391.5},
  URN =		{urn:nbn:de:0030-drops-4441},
  doi =		{10.4230/DagSemProc.05391.5},
  annote =	{Keywords: Reliable algorithms, stochastic traffic modeling, multibody modeling tools, geometric modeling}
}
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