@article{LemoineNavaWalterKoerkeletal., author = {Lemoine-Nava, Roberto and Walter, Sebastian F. and K{\"o}rkel, Stefan and Engell, Sebastian}, title = {Online Optimal Experiment Design: Reduction of the Number of Variables}, series = {IFAC-PapersOnLine}, volume = {49}, journal = {IFAC-PapersOnLine}, number = {7}, publisher = {Elsevier}, doi = {10.1016/j.ifacol.2016.07.302}, pages = {889 -- 894}, abstract = {In this work, a method for reducing the number of degrees of freedom in online optimal dynamic experiment design problems for systems described by differential equations is proposed. The online problems are posed such that only the inputs which extend an operation policy resulting from an experiment designed offline are optimized. This is done by formulating them as multiple experiment designs, considering explicitly the information of the experiment designed offline and possible time delays unknown a priori. The performance of the method is shown for the case of the separation of isopropanolol isomers in a Simulated Moving Bed plant.}, language = {en} } @misc{WeberDendorferSuessetal., author = {Weber, Karsten and Dendorfer, Sebastian and S{\"u}ß, Franz and Kubowitsch, Simone and Schratzenstaller, Thomas and Haug, Sonja and Mohr, Christa and Kiesl, Hans and Drechsler, J{\"o}rg and Westner, Markus and Kobus, J{\"o}rn and Schubert, Martin J. W. and Zenger, Stefan and Pietsch, Alexander and Weiß, Josef and Hinterseer, Sebastian and Schieck, Roland and Scherzinger, Stefanie and Klettke, Meike and Ringlstetter, Andreas and St{\"o}rl, Uta and Bissyand{\´e}, Tegawend{\´e} F. and Seeburger, Achim and Schindler, Timo and Ramsauer, Ralf and Kiszka, Jan and K{\"o}lbl, Andreas and Lohmann, Daniel and Mauerer, Wolfgang and Maier, Johannes and Scorna, Ulrike and Palm, Christoph and Soska, Alexander and Mottok, J{\"u}rgen and Ellermeier, Andreas and V{\"o}gele, Daniel and Hierl, Stefan and Briem, Ulrich and Buschmann, Knut and Ehrlich, Ingo and Pongratz, Christian and Pielmeier, Benjamin and Tyroller, Quirin and Monkman, Gareth J. and Gut, Franz and Roth, Carina and Hausler, Peter and Bierl, Rudolf and Prommesberger, Christian and Ławrowski, Robert Damian and Langer, Christoph and Schreiner, Rupert and Huang, Yifeng and She, Juncong and Ottl, Andreas and Rieger, Walter and Kraml, Agnes and Poxleitner, Thomas and Hofer, Simon and Heisterkamp, Benjamin and Lerch, Maximilian and Sammer, Nike and Golde, Olivia and Wellnitz, Felix and Schmid, Sandra and Muntschick, Claudia and Kusterle, Wolfgang and Paric, Ivan and Br{\"u}ckl, Oliver and Haslbeck, Matthias and Schmidt, Ottfried and Schwanzer, Peter and Rabl, Hans-Peter and Sterner, Michael and Bauer, Franz and Steinmann, Sven and Eckert, Fabian and Hofrichter, Andreas}, title = {Forschungsbericht 2017}, editor = {Baier, Wolfgang}, address = {Regensburg}, organization = {Ostbayerische Technische Hochschule Regensburg}, isbn = {978-3-9818209-3-5}, doi = {10.35096/othr/pub-1383}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-13835}, subject = {Forschung}, language = {de} } @article{BarzSeligerMarxetal., author = {Barz, Tilman and Seliger, Dominik and Marx, Klemens and Sommer, Andreas and Walter, Sebastian F. and Bock, Hans Georg and Koerkel, Stefan}, title = {State and state of charge estimation for a latent heat storage}, series = {Control Engineering Practice}, volume = {72}, journal = {Control Engineering Practice}, publisher = {Pergamon-Elsevier d.}, doi = {10.1016/j.conengprac.2017.11.006}, pages = {151 -- 166}, abstract = {A nonlinear state observer is designed for a thermal energy storage with solid/liquid phase change material (PCM). Using a physical 2D dynamic model, the observer reconstructs transient spatial temperature fields inside the storage and estimates the stored energy and the state of charge. The observer has been successfully tested with a lab-scale latent heat storage with a single pass tube bundle and the phase change material located in a shell around each tube. It turns out that the observer robustly tracks the real process data with as few as four internal PCM temperature sensors. © 2017 Elsevier Ltd. All rights reserved.}, language = {en} } @article{JostKudrussKoerkeletal., author = {Jost, Felix and Kudruss, Manuel and Koerkel, Stefan and Walter, Sebastian F.}, title = {A computational method for key-performance-indicator-based parameter identification of industrial manipulators}, series = {Journal of mathematics in Industry}, volume = {7}, journal = {Journal of mathematics in Industry}, number = {9}, publisher = {Springer Nature}, doi = {10.1186/s13362-017-0039-7}, abstract = {We present a novel derivative-based parameter identification method to improve the precision at the tool center point of an industrial manipulator. The tool center point is directly considered in the optimization as part of the problem formulation as a key performance indicator. Additionally, our proposed method takes collision avoidance as special nonlinear constraints into account and is therefore suitable for industrial use. The performed numerical experiments show that the optimum experimental designs considering key performance indicators during optimization achieve a significant improvement in comparison to other methods. An improvement in terms of precision at the tool center point of 40\% to 44\% was achieved in experiments with three KUKA robots and 90 notional manipulator models compared to the heuristic experimental designs chosen by an experimenter as well as 10\% to 19\% compared to an existing state-of-the-art method.}, language = {en} } @article{WalterSchmidtKoerkel, author = {Walter, Sebastian F. and Schmidt, Andrea and K{\"o}rkel, Stefan}, title = {Adjoint-based optimization of experimental designs with many control variables}, series = {Journal of Process Control}, volume = {24}, journal = {Journal of Process Control}, number = {10}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0959-1524}, doi = {10.1016/j.jprocont.2014.06.019}, pages = {1504 -- 1515}, abstract = {We propose a method for an efficient optimization of experimental designs, using a combination of discrete adjoint computations, Taylor arithmetic and matrix calculus. Compared to the state of the art of using finite differences or the forward mode of automatic differentiation, our proposed approach leads to a reduction of the relative temporal complexity from linear to constant time in the number of control variables and measurement weights. We demonstrate that the advantageous complexity results are not only of theoretical nature, but lead to significant speedups in practice as well. With our implementation we are very close to the theoretical bound of the cheap gradient principle. We present one academic (spatially discretized heat equation) and two industrial application examples (biochemical process/Diesel-oxidation catalysis process) where we achieve speedups that range between 10 and 100. In addition to our core results, we also describe an efficient adjoint approach for the treatment of differential algebraic equations and present adjoint formulas for constrained least-squares problems.}, language = {de} } @article{BarzLopezCKoerkeletal., author = {Barz, Tilman and L{\´o}pez C., Diana C. and K{\"o}rkel, Stefan and Walter, Sebastian F.}, title = {Real-time adaptive input design for the determination of competitive adsorption isotherms in liquid chromatography}, series = {Computers and Chemical Engineering}, volume = {94}, journal = {Computers and Chemical Engineering}, publisher = {Elsevier}, doi = {10.1016/j.compchemeng.2016.07.009}, pages = {104 -- 116}, abstract = {The adaptive input design (also called online redesign of experiments) for parameter estimation is very effective for the compensation of uncertainties in nonlinear processes. Moreover, it enables substantial savings in experimental effort and greater reliability in modeling. We present theoretical details and experimental results from the real-time adaptive optimal input design for parameter estimation. The case study considers separation of three benzoate by reverse phase liquid chromatography. Following a receding horizon scheme, adaptive D-optimal input designs are generated for a precise determination of competitive adsorption isotherm parameters. Moreover, numerical techniques for the regularization of arising ill-posed problems, e.g. due to scarce measurements, lack of prior information about parameters, low sensitivities and parameter correlations are discussed. The estimated parameter values are successfully validated by Frontal Analysis and the benefits of optimal input designs are highlighted when compared to various standard/heuristic input designs in terms of parameter accuracy and precision.}, language = {en} }