TY  - CHAP
A1  - Wittig, M.
A1  - Rütters, René
A1  - Bragard, Michael
ED  - Reiff-Stephan, Jörg
ED  - Jäkel, Jens
ED  - Schwarz, André
T1  - Application of RL in control systems using the example of a rotatory inverted pendulum
T2  - Tagungsband AALE 2024 : Fit für die Zukunft: praktische Lösungen für die industrielle Automation
N2  - In this paper, the use of reinforcement learning (RL) in control systems is investigated using a rotatory inverted pendulum as an example. The control behavior of an RL controller is compared to that of traditional LQR and MPC controllers. This is done by evaluating their behavior under optimal conditions, their disturbance behavior, their robustness and their development process. All the investigated controllers are developed using MATLAB and the Simulink simulation environment and later deployed to a real pendulum model powered by a Raspberry Pi. The RL algorithm used is Proximal Policy Optimization (PPO). The LQR controller exhibits an easy development process, an average to good control behavior and average to good robustness. A linear MPC controller could show excellent results under optimal operating conditions. However, when subjected to disturbances or deviations from the equilibrium point, it showed poor performance and sometimes instable behavior. Employing a nonlinear MPC Controller in real time was not possible due to the high computational effort involved. The RL controller exhibits by far the most versatile and robust control behavior. When operated in the simulation environment, it achieved a high control accuracy. When employed in the real system, however, it only shows average accuracy and a significantly greater performance loss compared to the simulation than the traditional controllers. With MATLAB, it is not yet possible to directly post-train the RL controller on the Raspberry Pi, which is an obstacle to the practical application of RL in a prototyping or teaching setting. Nevertheless, RL in general proves to be a flexible and powerful control method, which is well suited for complex or nonlinear systems where traditional controllers struggle.
KW  - Rotatory Inverted Pendulum
KW  - MPC
KW  - LQR
KW  - PPO
KW  - Reinforcement Learning
Y1  - 2024
SN  - 978-3-910103-02-3
U6  - http://dx.doi.org/10.33968/2024.53
N1  - 20. AALE-Konferenz. Bielefeld, 06.03.-08.03.2024.
(Tagungsband unter https://doi.org/10.33968/2024.29)
SP  - 241
EP  - 248
PB  - le-tex publishing services GmbH
CY  - Leipzig
ER  - 
TY  - JOUR
A1  - Fagan, Andrew J.
A1  - Bitz, Andreas
A1  - Björkman-Burtscher, Isabella M.
A1  - Collins, Christopher M.
A1  - Kimbrell, Vera
A1  - Raaijmakers, Alexander J. E.
T1  - 7T MR Safety
JF  - Journal of Magnetic Resonance Imaging (JMRI)
Y1  - 2021
U6  - http://dx.doi.org/10.1002/jmri.27319
SN  - 1522-2586
VL  - 53
IS  - 2
SP  - 333
EP  - 346
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Fiedler, Thomas M.
A1  - Ladd, Mark E.
A1  - Clemens, Markus
A1  - Bitz, Andreas
T1  - Safety of subjects during radiofrequency exposure in ultra-high-field magnetic resonance imaging
JF  - IEEE Letters on Electromagnetic Compatibility Practice and Applications
N2  - Magnetic resonance imaging (MRI) is one of the most important medical imaging techniques. Since the introduction of MRI in the mid-1980s, there has been a continuous trend toward higher static magnetic fields to obtain i.a. a higher signal-to-noise ratio. The step toward ultra-high-field (UHF) MRI at 7 Tesla and higher, however, creates several challenges regarding the homogeneity of the spin excitation RF transmit field and the RF exposure of the subject. In UHF MRI systems, the wavelength of the RF field is in the range of the diameter of the human body, which can result in inhomogeneous spin excitation and local SAR hotspots. To optimize the homogeneity in a region of interest, UHF MRI systems use parallel transmit systems with multiple transmit antennas and time-dependent modulation of the RF signal in the individual transmit channels. Furthermore, SAR increases with increasing field strength, while the SAR limits remain unchanged. Two different approaches to generate the RF transmit field in UHF systems using antenna arrays close and remote to the body are investigated in this letter. Achievable imaging performance is evaluated compared to typical clinical RF transmit systems at lower field strength. The evaluation has been performed under consideration of RF exposure based on local SAR and tissue temperature. Furthermore, results for thermal dose as an alternative RF exposure metric are presented.
Y1  - 2020
SN  - 2637-6423
U6  - http://dx.doi.org/10.1109/LEMCPA.2020.3029747
VL  - 2
IS  - 3
SP  - 1
EP  - 8
PB  - IEEE
CY  - New York, NY
ER  - 
TY  - CHAP
A1  - Hofmann, Till
A1  - Limpert, Nicolas
A1  - Mataré, Viktor
A1  - Ferrein, Alexander
A1  - Lakemeyer, Gerhard
T1  - Winning the RoboCup Logistics League with Fast Navigation, Precise Manipulation, and Robust Goal Reasoning
T2  - RoboCup 2019: Robot World Cup XXIII. RoboCup
Y1  - 2019
SN  - 978-3-030-35699-6
U6  - http://dx.doi.org/10.1007/978-3-030-35699-6_41
N1  - Lecture Notes in Computer Science, vol 11531
SP  - 504
EP  - 516
PB  - Springer
CY  - Cham
ER  - 
TY  - CHAP
A1  - Hoegen, Anne von
A1  - Doncker, Rik W. De
A1  - Rütters, René
T1  - Teaching Digital Control of Operational Amplifier Processes with a LabVIEW Interface and Embedded Hardware
T2  - The 23rd International Conference on Electrical Machines and Systems (ICEMS), Hamamatsu, Japan
Y1  - 2020
U6  - http://dx.doi.org/10.23919/ICEMS50442.2020.9290928
SP  - 1117
EP  - 1122
ER  - 
TY  - CHAP
A1  - Ibanez-Sanchez, Gema
A1  - Wolf, Martin
T1  - Interactive Process Mining-Induced Change Management Methodology for Healthcare
T2  - Interactive Process Mining in Healthcare
N2  - The adoption of the Digital Health Transformation is a tremendous paradigm change in health organizations, which is not a trivial process in reality. For that reason, in this chapter, it is proposed a methodology with the objective to generate a changing culture in healthcare organisations. Such a change culture is essential for the successful implementation of any supporting methods like Interactive Process Mining. It needs to incorporate (mostly) new ways of team-based and evidence-based approaches for solving structural problems in a digital healthcare environment.
KW  - Methodology
KW  - Change culture
KW  - Lean thinking
KW  - Interactive process mining
KW  - Objective data
Y1  - 2020
SN  - 978-3-030-53993-1 (Online)
SN  - 978-3-030-53992-4 (Print)
U6  - http://dx.doi.org/10.1007/978-3-030-53993-1_16
SP  - 267
EP  - 293
PB  - Springer
CY  - Cham
ER  - 
TY  - JOUR
A1  - Hüning, Felix
A1  - Backes, Andreas
T1  - Direct observation of large Barkhausen jump in thin Vicalloy wires
JF  - IEEE Magnetics Letters
Y1  - 2020
SN  - 1949-307X
U6  - http://dx.doi.org/10.1109/LMAG.2020.3046411
VL  - 11
IS  - Art. 2506504
SP  - 1
EP  - 4
PB  - IEEE
CY  - New York, NY
ER  - 
TY  - CHAP
A1  - Hoegen, Anne von
A1  - Doncker, Rik W. De
A1  - Bragard, Michael
A1  - Hoegen, Svenja von
T1  - Problem-Based Learning in Automation Engineering: Performing a Remote Laboratory Session Serving Various Educational Attainments
T2  - 2021 IEEE Global Engineering Education Conference (EDUCON)
Y1  - 2021
U6  - http://dx.doi.org/10.1109/EDUCON46332.2021.9453925
SP  - 1605
EP  - 1614
ER  - 
TY  - CHAP
A1  - Hüning, Felix
A1  - Stüttgen, Marcel
T1  - Work in Progress: Interdisciplinary projects in times of COVID-19 crisis – challenges, risks and chances
T2  - 2021 IEEE Global Engineering Education Conference (EDUCON)
Y1  - 2021
U6  - http://dx.doi.org/10.1109/EDUCON46332.2021.9454006
SP  - 1175
EP  - 1179
ER  - 
TY  - JOUR
A1  - Altherr, Lena
A1  - Ederer, Thorsten
A1  - Lorenz, Ulf
A1  - Pelz, Peter F.
A1  - Pöttgen, Philipp
ED  - Lübbecke, Marco
ED  - Koster, Arie
ED  - Letmathe, Peter
ED  - Madlener, Reihard
ED  - Peis, Britta
ED  - Walther, Grit
T1  - Experimental validation of an enhanced system synthesis approach
JF  - Operations Research Proceedings 2014
N2  - Planning the layout and operation of a technical system is a common task
for an engineer. Typically, the workflow is divided into consecutive stages: First,
the engineer designs the layout of the system, with the help of his experience or of
heuristic methods. Secondly, he finds a control strategy which is often optimized
by simulation. This usually results in a good operating of an unquestioned sys-
tem topology. In contrast, we apply Operations Research (OR) methods to find a
cost-optimal solution for both stages simultaneously via mixed integer program-
ming (MILP). Technical Operations Research (TOR) allows one to find a provable
global optimal solution within the model formulation. However, the modeling error
due to the abstraction of physical reality remains unknown. We address this ubiq-
uitous problem of OR methods by comparing our computational results with mea-
surements in a test rig. For a practical test case we compute a topology and control
strategy via MILP and verify that the objectives are met up to a deviation of 8.7%.
Y1  - 2014
SN  - 978-3-319-28695-2
U6  - http://dx.doi.org/10.1007/978-3-319-28697-6_1
PB  - Springer
CY  - Basel
ER  -