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@inproceedings{faucris.118727224,
author = {Leyendecker, Sigrid and Koch, Michael and Ringkamp, Maik and Ober-Blöbaum, Sina},
booktitle = {Proceedings of WCCM XI - ECCM V - ECFD VI},
date = {2014-06-20/2014-06-25},
faupublication = {yes},
keywords = {non-smooth dynamics, contact problem, longjump, discrete mechanics, mixed integer optimal control},
note = {UnivIS-Import:2015-04-16:Pub.2014.tech.FT.ltd.adiscr{\_}5},
pages = {DVD},
peerreviewed = {Yes},
title = {{A} discrete variational approach to non-smooth dynamics and optimal control},
venue = {Barcelona},
year = {2014}
}
@inproceedings{faucris.121764984,
abstract = {Recently, a couple of approaches have been developed that combine multiobjective optimization with direct discretization methods to approximate trajectories of optimal control problems, resulting in restricted optimization problems of high dimension. The solution set of a multiobjective optimization problem is called the Pareto set which consists of optimal compromise solutions. A common way to approximate the Pareto set is to start with at least one given Pareto point and to evolve the Pareto set using a local continuation method. With our approach, we first roughly approximate the feasible set of the multiobjective optimal control problem by using a global root finding approach. The roughly approximated feasible set provides information to find an appropriate scaling of the single objectives and to find initial guesses for the continuation of the Pareto set. Then, the continuation is performed by a reference point method. To reduce the dimension of the underlying optimal control problem, a local reparametrization in combination with a discrete null space method is use},
author = {Ringkamp, Maik and Ober-Blöbaum, Sina and Leyendecker, Sigrid},
booktitle = {Proceedings of the ECCOMAS Thematic Conference on Mutlibody Dynamics},
date = {2013-07-01/2013-07-04},
faupublication = {yes},
keywords = {Discrete mechanics; Kinematic chain; Multiobjective optimization; Null space method; Optimal control; Reference point method},
note = {UnivIS-Import:2015-04-16:Pub.2013.tech.FT.ltd.anumer},
pages = {DVD, 11 Seiten},
peerreviewed = {Yes},
title = {{A} numerical approach to multiobjective optimal control of multibody dynamics},
venue = {Zagreb},
year = {2013}
}
@inproceedings{faucris.121416944,
author = {Ringkamp, Maik and Ober-Blöbaum, Sina and Leyendecker, Sigrid},
booktitle = {Proc. Appl. Math. Mech (PAMM)},
date = {2014-03-10/2014-03-14},
doi = {10.1002/pamm.201410440},
faupublication = {yes},
peerreviewed = {unknown},
publisher = {Proc. Appl. Math. Mech.},
title = {{Discrete} mechanics and mixed integer optimal control of dynamical systems},
venue = {Erlangen},
year = {2014}
}
@article{faucris.120336964,
abstract = {In this work, we optimally control the upright gait of a three-dimensional symmetric bipedal walking model with flat feet. The whole walking cycle is assumed to occur during a fixed time span while the time span for each of the cycle phases is variable and part of the optimization. The implemented flat foot model allows to distinguish forefoot and heel contact such that a half walking cycle consists of five different phases. A fixed number of discrete time nodes in combination with a variable time interval length assure that the discretized problem is differentiable even though the particular time of establishing or releasing the contact between the foot and the ground is variable. Moreover, the perfectly plastic contact model prevents penetration of the ground. The optimal control problem is solved by our structure preserving discrete mechanics and optimal control for constrained systems (DMOCC) approach where the considered cost function is physiologically motivated and the obtained results are analyzed with regard to the gait of humans walking on a horizontal and an inclined plan},
author = {Koch, Michael and Ringkamp, Maik and Leyendecker, Sigrid},
doi = {10.1115/1.4035213},
faupublication = {yes},
journal = {Journal of Computational and Nonlinear Dynamics},
peerreviewed = {Yes},
title = {{Discrete} {Mechanics} and {Optimal} {Control} of {Walking} {Gaits}},
volume = {12},
year = {2017}
}
@masterthesis{faucris.114858524,
author = {Ringkamp, Maik},
faupublication = {no},
note = {UnivIS-Import:2016-07-26:Pub.2009.tech.FT.ltd.fortse},
peerreviewed = {automatic},
school = {Friedrich-Alexander-Universität Erlangen-Nürnberg},
title = {{Fortsetzungsalgorithmen} für hochdimensionale {Mehrzieloptimierungsprobleme}},
year = {2009}
}
@article{faucris.112890404,
abstract = {In many applications, several conflicting objectives have to be optimized concurrently leading to a multi-objective optimization problem. Since the set of solutions, the so-called Pareto set, typically forms a (k1)-dimensional manifold, where k is the number of objectives considered in the model, continuation methods such as predictor-corrector (PC) methods are in certain cases very efficient tools for rapidly computing a finite size representation of the set of interest. However, their classical implementation leads to trouble when considering higher-dimensional models (i.e. for dimension n>1000 of the parameter space). In this work, it is proposed to perform a successive approximation of the tangent space which allows one to find promising predictor points with less effort in particular for high-dimensional models since no Hessians of the objectives have to be calculated. The applicability of the resulting PC variant is demonstrated on a benchmark model for up to n=100, 000 parameters. © 2012 Taylor & Francis.},
author = {Ringkamp, Maik and Ober-Blöbaum, Sina and Dellnitz, Michael and Schütze, Oliver},
doi = {10.1080/0305215X.2011.634407},
faupublication = {yes},
journal = {Engineering Optimization},
keywords = {continuation; high-dimensional problems; multi-objective optimization; tangent space approximation},
note = {UnivIS-Import:2015-03-09:Pub.2012.tech.FT.ltd.handli},
pages = {1117-1146},
peerreviewed = {Yes},
title = {{Handling} high dimensional problems with multi-objective continuation methods via successive approximation of the tangent space},
volume = {44},
year = {2012}
}
@incollection{faucris.107920604,
abstract = {After the domain-spanning conceptual design, engineers from different domains work in parallel and apply their domain-specific methods and modeling languages to design the system. Vital for the successful design, are system optimization methods and the design of the reconfiguration behavior. The former methods enable the parametric adaption of the system’s behavior, e.g. an adaption of controller parameters, according to a current selection of the system’s objectives. The latter realizes structural adaption of the system’s behavior, e.g. the exchange of software or hardware parts. Altogether, this leads to a complex system behavior that is hard to overview. In addition, self-optimizing systems are used in safety-critical environments. Consequently, the system’s safety-critical behavior has to undergo a rigorous verification and testing process. Existing design methods do not address all of these challenges together. Indeed, a combination of established design methods for traditional technical systems with novel methods that focus on these challenges is necessary. In this chapter, we will focus on such new methods. We will introduce new system optimization and design methods to develop reconfigurations of the software and the microelectronics. In order to ensure the correctness of safety-critical functionality, we propose new testing methods and formal methods to ensure safety-properties of the software. We show how to apply virtual prototyping to deal with the complexity of self-optimizing systems and perform an early analysis of the overall system. As each domain applies its own modeling languages, the result of these methods are several overlapping models. In order to keep these domain-specific models consistent among all domains, we will introduce a new semi-automatic model synchronization technique. Each of these design methods are integrated with the reference process for the development of self-optimizing system},
address = {Berlin Heidelberg},
author = {Ringkamp, Maik and Dellnitz, Michael},
booktitle = {Develop Intelligent Technical Systems of the Future},
doi = {10.1007/978-3-642-45435-6{\_}5},
faupublication = {yes},
isbn = {978-3-642-45435-6},
pages = {183-350},
peerreviewed = {unknown},
publisher = {Springer},
series = {Lecture Notes in Mechanical Engineering},
title = {{Hierarchical} {Multiobjective} {Optimization}},
year = {2014}
}
@inproceedings{faucris.107924564,
author = {Ringkamp, Maik and Leyendecker, Sigrid and Ober-Blöbaum, Sina},
booktitle = {Proc. Appl. Math. Mech (PAMM)},
date = {2013-03-18/2013-03-22},
doi = {10.1002/pamm.201310009},
faupublication = {yes},
peerreviewed = {unknown},
publisher = {Proc. Appl. Math. Mech.},
title = {{Multiobjective} optimal control of a four body kinematic chain},
venue = {Novi Sad},
year = {2013}
}
@incollection{faucris.108872984,
abstract = {Nonlinear control systems with instantly changing dynamical behavior can be modeled by introducing an additional control function that is integer valued in contrast to a control function that is allowed to have continuous values. The discretization of a mixed integer optimal control problem (MIOCP) leads to a non differentiable optimization problem and the non differentiability is caused by the integer values. The paper is about a time transformation method that is used to transform a MIOCP with integer dependent constraints into an ordinary optimal control problem. Differentiability is achieved by replacing a variable integer control function with a fixed integer control function and a variable time allows to change the sequence of active integer values. In contrast to other contributions, so called control consistent fixed integer control functions are taken into account here. It is shown that these control consistent fixed integer control functions allow a better accuracy in the resulting trajectories, in particular in the computed switching times. The method is verified on analytical and numerical example},
author = {Ringkamp, Maik and Ober-Blöbaum, Sina and Leyendecker, Sigrid},
booktitle = {Mathematical Programming},
doi = {10.1007/s10107-016-1023-5},
faupublication = {yes},
keywords = {Time transformation Control consistency Optimal control Mixed integer optimal control Hybrid systems Switched dynamical systems},
pages = {1-31},
peerreviewed = {unknown},
publisher = {Springer Berlin Heidelberg},
title = {{On} the time transformation of mixed integer optimal control problems using a consistent fixed integer control function},
year = {2016}
}
@inproceedings{faucris.113628064,
author = {Ringkamp, Maik and Ober-Blöbaum, Sina and Leyendecker, Sigrid},
booktitle = {ECCOMAS},
date = {2015-06-29/2015-07-02},
faupublication = {yes},
peerreviewed = {unknown},
title = {{Relaxing} mixed integer optimal control problems using a time transformation},
venue = {Barcelona},
year = {2015}
}
@inproceedings{faucris.122401884,
author = {Ringkamp, Maik and Ober-Blöbaum, Sina and Leyendecker, Sigrid},
booktitle = {Proc. Appl. Math. Mech (PAMM)},
date = {2015-03-23/2015-03-27},
doi = {10.1002/pamm.201510008},
faupublication = {yes},
pages = {27-30},
peerreviewed = {unknown},
publisher = {Proc. Appl. Math. Mech.},
title = {{Relaxing} mixed integer optimal control problems using a time transformation},
venue = {Lecce},
year = {2015}
}
@inproceedings{faucris.122573924,
author = {Leyendecker, Sigrid and Koch, Michael and Ringkamp, Maik and Ober-Blöbaum, Sina},
booktitle = {Foundations of Computational Mathematics},
date = {2014-12-11/2014-12-20},
faupublication = {yes},
peerreviewed = {unknown},
title = {{Structure} preserving integration of hybrid dynamical systems and optimal control},
venue = {Montevideo},
year = {2014}
}
@inproceedings{faucris.113341404,
author = {Leyendecker, Sigrid and Koch, Michael and Ringkamp, Maik and Ober-Blöbaum, Sina},
booktitle = {3rd German-Japanese Workshop on Computational Mechanics},
date = {2015-03-30/2015-03-31},
faupublication = {yes},
peerreviewed = {unknown},
title = {{Structure} preserving simulation of hybrid dynamical systems and optimal control},
venue = {Munich},
year = {2015}
}
@inproceedings{faucris.123412124,
author = {Ringkamp, Maik and Ober-Blöbaum, Sina and Leyendecker, Sigrid},
booktitle = {Proc. Appl. Math. Mech (PAMM)},
date = {2016-03-07/2016-03-11},
doi = {10.1002/pamm.201610383},
faupublication = {yes},
publisher = {Proc. Appl. Math. Mech.},
title = {{Time} transformed mixed integer optimal control problems with impacts},
venue = {Braunschweig},
year = {2016}
}