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Chair for Dynamics/Mechatronics
ITM Logo

Prof. Wolfgang Seemann
Prof. Carsten Proppe
Prof. Alexander Fidlin


Karlsruher Institut für Technologie (KIT)
Kaiserstraße 10
Gebäude: 10.23, 2. OG
76131 Karlsruhe

Tel:  +49 721 608-42397
Tel:  +49 721 608-42659
Fax: +49 721 608-46070
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Quick guide Dynamics/Mechatronics

Dr.-Ing. Ulrich Römer

Research Assistant
Office Hours: 

by appointment

Room: 205.2
Phone: +49 721 608-46823
Fax: +49 721 608-46070
ulrich roemerEnu5∂kit edu

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


Energy Efficient Bipedal Robots

Five link walker with elastic coupling

Passive dynamic walker

Passive dynamic walker with elastic coupling

One of the biggest challenges for todays humanoid robots is energy efficiency. To evaluate the efficiency of bipedal locomotion the dimensionless specific energetic cost of transportation, cot = (energy used)/(weight × distance traveled) is used. At a walking speed of 0.4 m/s the state-of-the-art humanoid Honda Asimo with cot = 3.2 is very inefficient compared to humans with cot = 0.2. The main cause for this bad energy efficiency is the control strategy of humanoid robots which fights against gravitation and tries to suppress any natural dynamics. Humans on the other hand walk with gravitation – they use their natural dynamics instead of struggling against it. Their body even consists of springs in the shape of tendons to influence the dynamics and buffer energy during the walking cycle.

Our method to improve the energy efficiency of bipedal walkers consists of a two-track approach. On the first hand an alternative control strategy is used, which allows for evolvement of natural dynamics, based on input–output linearisation. On the other hand the natural dynamics of the underlying mechanical subsystem is optimized by introducing elastic couplings between different links. Numerical optimization is used to determine simultaneously the desired joint trajectories as well as the best elastic coupling.

With elastic couplings the cost of transportation can be reduced significantly. There are mainly two reasons for the energy savings. First of all the natural frequency of the swing leg can be adjusted to the locomotion speed in order to be operated near resonance. The elasticity helps not only to accelerate the swing leg but also to decelerate and to transform kinetic energy into potential energy, which otherwise would get lost for the system during breaking or at the impact. Finally it can be stated that significant gains in energy efficiency can be made by allowing and optimizing the natural dynamics with elastic couplings.

Contact: Prof. A. Fidlin, Prof. W. Seemann, U. Römer


Über den Einfluss der Fußgeometrie auf die Energieeffizienz beim zweibeinigen Gehen. Dissertation.
Römer, U. J.
2019. KIT Scientific Publishing, Karlsruhe. doi:10.5445/KSP/1000089994

Publications in Journals and Conference Proceedings

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, IEEE, Piscataway (NJ). doi:10.1109/ICRA.2016.7487271
Investigation of optimal bipedal walking gaits subject to different energy-based objective functions.
Römer, U.; Fidlin, A.; Seemann, W.
2015. Proceedings in applied mathematics and mechanics, 15 (1), 69–70. doi:10.1002/pamm.201510025
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.201410028
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, Singapore. doi:10.1142/9789814623353_0048

Talks at Conferences and Colloquia

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), München, Deutschland, 19.–23. März 2018
Dance-like motions in optimal walking.
Römer, U. J.; Fidlin, A.
2017. 9th European Nonlinear Dynamics Conference (ENOC 2017), Budapest, Ungarn, 25.–30. Juni 2017 Volltext Volltext der Publikation als PDF-Dokument
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), Braunschweig, Deutschland, 7.–11. März 2016
A novel analytical foot rollover model for planar walking.
Römer, U. J.; Fidlin, A.
2016. Dynamic Walking (2016), Holly, MI, USA, 4.–7. Juni 2016 Volltext Volltext der Publikation als PDF-Dokument
Energy optimization of bipedal walking through parallel springs.
Römer, U.; Bauer, F.; Seemann, W.; Fidlin, A.
2014, Mai 14. 4th French-German-Japanese Conference on Humanoid and Legged Robots (2014), Heidelberg, Deutschland, 12.–14. Mai 2014


Offered theses
Title Type Date

Completed theses
Title Type Graduand
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