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Authors:Bernhard Bachmann: Dept. Mathematics and Engineering, University of Applied Sciences, Bielefeld, Germany
Lennart Ochel: Dept. Mathematics and Engineering, University of Applied Sciences, Bielefeld, Germany
Vitalij Ruge: Dept. Mathematics and Engineering, University of Applied Sciences, Bielefeld, Germany
Mahder Gebremedhin: PELAB – Programming Environment Lab, Dept. Computer Science Linköping University, Linköping, Sweden
Peter Fritzson: PELAB – Programming Environment Lab, Dept. Computer Science Linköping University, Linköping, Sweden
Vaheed Nezhadali: Vehicular Systems, Dept. Electrical Engineering Linköping University, Linköping, Sweden
Lars Eriksson: Vehicular Systems, Dept. Electrical Engineering Linköping University, Linköping, Sweden
Martin Sivertsson: Vehicular Systems, Dept. Electrical Engineering Linköping University, Linköping, Sweden
Publication title:Parallel Multiple-Shooting and Collocation Optimization with OpenModelica
Conference:Proceedings of the 9th International MODELICA Conference; September 3-5; 2012; Munich; Germany
Publication type: Abstract and Fulltext
Issue:076
Article No.:067
Abstract:Nonlinear model predictive control (NMPC) has become increasingly important for today’s control engineers during the last decade. In order to apply NMPC a nonlinear optimal control problem (NOCP) must be solved which needs a high computational effort.

State-of-the-art solution algorithms are based on multiple shooting or collocation algorithms; which are required to solve the underlying dynamic model formulation. This paper describes a general discretization scheme applied to the dynamic model description which can be further concretized to reproduce the mul-tiple shooting or collocation approach. Furthermore; this approach can be refined to represent a total collocation method in order to solve the underlying NOCP much more efficiently. Further speedup of optimization has been achieved by parallelizing the calculation of model specific parts (e.g. constraints; Jacobians; etc.) and is presented in the coming sections.

The corresponding discretized optimization problem has been solved by the interior optimizer Ipopt. The proposed parallelized algorithms have been tested on different applications. As industrial relevant application an optimal control of a Diesel-Electric power train has been investigated. The modeling and problem description has been done in Optimica and Modelica. The simulation has been performed using OpenModelica. Speedup curves for parallel execution are presented.

Language:English
Keywords:Modelica; Optimica; optimization; multiple shooting; collocation; parallel; simulation
Year:2012
No. of pages:10
Pages:659-668
ISBN:978-91-7519-826-2
Series:Linköping Electronic Conference Proceedings
ISSN (print):1650-3686
ISSN (online):1650-3740
File:http://www.ep.liu.se/ecp/076/067/ecp12076067.pdf
Available:2012-11-19
Publisher:Linköping University Electronic Press; Linköpings universitet

REFERENCE TO THIS PAGE
Bernhard Bachmann, Lennart Ochel, Vitalij Ruge, Mahder Gebremedhin, Peter Fritzson, Vaheed Nezhadali, Lars Eriksson, Martin Sivertsson (2012). Parallel Multiple-Shooting and Collocation Optimization with OpenModelica, Proceedings of the 9th International MODELICA Conference; September 3-5; 2012; Munich; Germany http://dx.doi.org/10.3384/ecp12076659 (accessed 12/22/2014)