Dr.-Ing.  Ulrich Römer

Dr.-Ing. Ulrich Römer

  • Postanschrift:
    Karlsruher Institut für Technologie
    Institut für Technische Mechanik
    Teilinstitut Dynamik/Mechatronik
    Postfach 6980
    76049 Karlsruhe

    Haus- und Lieferanschrift:
    KIT-Campus Süd
    Institut für Technische Mechanik
    Teilinstitut Dynamik/Mechatronik
    Geb. 10.23 R 205.2
    Kaiserstraße 10
    76131 Karlsruhe

Research

Design of bipedal robots with optimized energy efficiency in varying environments

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mean energy consumption per distance over different climbing inclination angles
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energy consumption per distance over different walking speeds

In the development of biped robots, energy efficient locomotion via walking or running is a major research priority. Due to the limited energy storage (battery), energy efficiency significantly determines the walking distance that can be covered. Energy efficiency depends not only on the controller used for stabilizing the motion, but also on the structural design and its mechanical model parameters. Hence, the purpose of this research is to develop and apply a method to systematically optimize the structure of a bipedal robot to maximize energy efficiency in different environments.

In the first step we consider an underactuated robot model which consists of five segments. Its rigid segments are additionally connected by elastic couplings such as torsion springs. Knowing that the robot’s periodic walking or running gaits can be analyzed as limit cycles of the controlled mechanical system, its resonance frequency can be adjusted to match the current step frequency by modifying the elastic couplings. A systematic approach to achieve this matching consists in the simultaneous optimization of the elastic couplings and the controlled motion. Consequently, the robot exploits the mechanical system's natural dynamics instead of wasting energy on its suppression.

Since the optimization of the parameters essentially depends on the conditions of the environment and the gait, the focus is on how the adaptation of the robot to the current operating state can be realized. Unlike the motion, which can be continuously updated by the controller based on the measured state variables, the elastic couplings need to be optimized to achieve the best characteristics by using "compliant smart mechanics" (COSM). Between the stance and swing phases of the robot’s legs, and especially during switching processes of the movement, an optimal (force-displacement and/or force-velocity) characteristic of COSM leads to an overall high energy efficiency for a wide range of walking scenarios.

This project is being carried out jointly by two research groups: The Compliant Systems Group (FG NSYS) from the Ilmenau University of Technology (TU Ilmenau) and the Institute of Engineering Mechanics (ITM) from the Karlsruhe Institute of Technology (KIT). While the team at TU Ilmenau investigates the compliant mechanical systems and their design and implementation, the team at KIT simulates and optimizes bipedal robots with those COSM mechanisms in different environments. It is financially supported by the German Research Foundation (DFG), grant FI 1761/4-1 | ZE 714/16-1.

 

Project partner: Prof. L. Zentner, M. Zirkel.

Contact: Prof. A. Fidlin, Dr. U. Römer, Y. Luo

Monographs

Publications in Journals and Conference Proceedings


Improving Energy Efficiency of a Bipedal Walker with Optimized Nonlinear Elastic Coupling
Luo, Y.; Römer, U. J.; Zentner, L.; Fidlin, A.
2022. Advances in Nonlinear Dynamics – Proceedings of the Second International Nonlinear Dynamics Conference (NODYCON 2021), Volume 2. Ed.: W. Lacarbonara, 253–262, Springer International Publishing. doi:10.1007/978-3-030-81166-2_23Full textFull text of the publication as PDF document
Improving energy efficiency of bipedal walking using nonlinear compliant mechanisms
Luo, Y.; Zirkel, M.; Römer, U. J.; Zentner, L.; Fidlin, A.
2021. Proceedings in applied mathematics and mechanics, 21 (1), e202100197. doi:10.1002/pamm.202100197Full textFull text of the publication as PDF document
Anwendung einer Homotopie-Optimierungs-Methode zur Identifikation der Modellparameter eines Roboterprototyps
Luo, Y.; Römer, U. J.; Riegraf, S.; Fidlin, A.; Zirkel, M.; Zentner, L.
2021. 3. VDI-Fachtagung: Schwingungen 2021 ; Würzburg, 16. und 17. November 2021, 259–272, VDI Verlag. doi:10.51202/9783181023914-259
The Influence of ground inclination on the energy efficiency of a bipedal walking robot
Luo, Y.; Römer, U. J.; Fidlin, A.
2021. Proceedings in applied mathematics and mechanics, 20 (1), e202000142. doi:10.1002/pamm.202000142Full textFull text of the publication as PDF document
Parameter Study of Compliant Elements for a Bipedal Robot to Increase Its Walking Efficiency
Zirkel, M.; Luo, Y.; Römer, U. J.; Fidlin, A.; Zentner, L.
2021. Microactuators, Microsensors and Micromechanisms : MAMM 2020. Ed.: L. Zentner, 58–75, Springer International Publishing. doi:10.1007/978-3-030-61652-6_6
A Brief Survey on Non-standard Constraints: Simulation and Optimal Control
Kern, D.; Römer, U. J.
2019. 8th GACM Colloquium on Computational Mechanics For Young Scientists From Academia and Industry, August 28th – 30th, 2019, University of Kassel, Germany Proceedings. Ed.: T. Gleim, 211–214, Kassel University Press Full textFull text of the publication as PDF document
Simultaneous optimization of gait and design parameters for bipedal robots
Römer, U. J.; Kuhs, C.; Krause, M. J.; Fidlin, A.
2016. Proceedings of the 2016 IEEE International Conference on Robotics and Automation (ICRA), Stockholm, Sweden 16-21 May 2016, 1374–1381, Institute of Electrical and Electronics Engineers (IEEE). doi:10.1109/ICRA.2016.7487271Full textFull text of the publication as PDF document
Energy-optimized bipedal running of a simple humanoid robot
Römer, U.; Fidlin, A.
2014. Proceedings in applied mathematics and mechanics, 14 (1), 81–82. doi:10.1002/pamm.201410028Full textFull text of the publication as PDF document
Transition from walking to running of a bipedal robot to optimize energy efficiency
Römer, U.; Bauer, F.; Fidlin, A.
2014. 17th International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines, CLAWAR 2014, Poznan, Poland; 21 - 23 July, 2014, 409–416, World Scientific Publishing. doi:10.1142/9789814623353_0048Full textFull text of the publication as PDF document

Talks at Conferences and Colloquia


Collision detection for rigid superellipsoids using the normal parameterization
Römer, U. J.
2021, August 24. 25th International Congress of Theoretical and Applied Mechanics (ICTAM 2021), Online, August 22–27, 2021 Full textFull text of the publication as PDF document
Kontaktdetektion zwischen konvexen Objekten auf Basis der Normalenparameterisierung
Römer, U. J.; Seemann, W.; Fidlin, A.
2020. 6. IFToMM D-A-CH Konferenz 2020 : 27./28. Februar 2020, Campus Technik Lienz. doi:10.17185/duepublico/71212Full textFull text of the publication as PDF document
Two-dimensional contact problems revisited – explicit analytical solutions for contact detection with straight and circular counterparts
Römer, U. J.; Fidlin, A.; Seemann, W.
2018. 89. Jahrestagung der Gesellschaft für angewandte Mathematik und Mechanik (GAMM 2018), Munich, Germany, March 19–23, 2018
Dance-like motions in optimal walking
Römer, U. J.; Fidlin, A.
2017. 9th European Nonlinear Dynamics Conference (ENOC 2017), Budapest, Hungary, June 25–30, 2017 Full textFull text of the publication as PDF document
Design and optimization of hybrid zero dynamics for a bipedal walking robot with series elastic actuators
Römer, U. J.; Fidlin, A.; Seemann, W.
2016. 87. Jahrestagung der Gesellschaft für angewandte Mathematik und Mechanik (GAMM 2016), Brunswick, Germany, March 7–11, 2016
A novel analytical foot rollover model for planar walking
Römer, U. J.; Fidlin, A.
2016. Dynamic Walking (2016), Holly, MI, USA, June 4–7, 2016 Full textFull text of the publication as PDF document
Energy optimization of bipedal walking through parallel springs
Römer, U.; Bauer, F.; Seemann, W.; Fidlin, A.
2014, May 14. 4th French-German-Japanese Conference on Humanoid and Legged Robots (2014), Heidelberg, Germany, May 12–14, 2014

Theses

Offered theses
Title Type Date
Master Thesis as of now
Thesis (B.Sc. or M.Sc.) as of now
Thesis (B.Sc. or M.Sc.) as of now
Completed theses
Title Type Graduand
Masterarbeit

Alexander Stoychev

Masterarbeit

David Holderle

Masterarbeit

Amira Khelifi

Master thesis

Alexander Michael Dyck

Master thesis

Yonzhou Zhang

Bachelor thesis

Daniel Debertin

Bachelor thesis

Franziska Krebs

Master thesis

Jimmy Alberto Aramendiz Fuentes

Bachelor thesis

Jan-Hendrik Witt

Bachelor thesis

Shreyas Vivek Joshi

Master thesis

Simon Lüdke

Master thesis

Cornelius Kuhs 

Bachelor thesis

Timo Fetzer 

Bachelor thesis

Jan Wachter 

Bachelor thesis

Sonja Marahrens 

Bachelor thesis

Simeon Braun

Master thesis

Philipp König

Bachelor thesis

Christian Pihuave

Teaching

Most courses offered by the Institute of Engineering Mechanics are in German. For more information on past and current courses offered by me please visit the German version of this website.