Dipl.-Ing. Fabian Bauer

Dr.-Ing. Fabian Bauer

  • Karlsruher Institut für Technologie (KIT)
    Kaiserstraße 10
    Gebäude: 10.23
    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, F. Bauer, U. Römer



Optimierung der Energieeffizienz zweibeiniger Roboter durch elastische Kopplungen.
PhD Thesis, Karlsruhe Institute of Technology, 05/2015, DOI 10.5445/KSP/1000042846 


Publications in Journals und Proceedings

F. Bauer, U. Römer, A. Fidlin, W. Seemann (2016)
Optimal elastic coupling in form of one mechanical spring to improve energy efficiency of walking bipedal robots
Multibody System Dynamics, 38(3), pp. 227-262, 2016. 
DOI 10.1007/s11044-016-9509-8, submitted version as pdf.

F. Bauer, U. Römer, A. Fidlin, W. Seemann (2016)
Optimization of energy efficiency of walking bipedal robots by use of elastic couplings in the form of mechanical springs
Nonlinear Dynamics, Vol. 83, No. 3, pp. 1275-1301, 2016.
DOI 10.1007/s11071-015-2402-9, submitted version as pdf.

F. Bauer, A. Fidlin, W. Seemann (2014)
Energy efficient bipedal robots walking in resonance.
Journal of Applied Mathematics and Mechanics, DOI 10.1002/zamm.201300245

U. Römer, F. Bauer, A. Fidlin (2014)
Transition from walking to running of a bipedal robot to optimize energy efficiency.
Proceedings of the 2014 Conference on Climbing and Walking Robots (Clawar 2014), Poznan, Poland

D. Budday, F. Bauer, J. Seipel (2012)
Stability and Robustness of a 3D SLIP Model for Walking Using Lateral Leg Placement Control.
Proceedings of the 2012 ASME IDETC Chicago, Illinois, USA, IDETC2012-71154

C. Simonidis, G. Stelzner, W. Seemann, F. Bauer (2011)
Modeling and synthesis of human motion within the collaborative research center 588.
IUTAM Symposium on Human Body Dynamics, Procedia IUTAM Volume 2, 2011, pp. 275–289; link to pdf

F. Bauer, H. Hetzler, A. Pagel, W. Seemann (2010)
Do Non-linearities Enhance Stability of Bipedal Locomotion?
Proceedings of SIMPAR 2010 Workshops, Darmstadt, Germany, pp. 104-112; link to pdf

C. Simonidis, T. Stein, F. Bauer, A. Fischer, H. Schwameder, W. Seemann (2009)
Determining the principles of human motion by combining motion analysis and motion synthesis.
Proceedings of the 2009 IEEE-RAS International Conference on Humanoid Robots (Humanoids 2009), Paris, France, pp. 317-322; link to pdf

C. Simonidis, T. Stein, A. Fischer, F. Bauer, H. Schwameder, W. Seemann (2009).
MKD-Tools: Ein Mehrkörperalgorithmus zur Analyse und Synthese menschlicher Bewegungen.
In: Wank, V., Hendrik Heger (Hrsg.): Biomechanik – Grundlagenforschung und Anwendung.
Schriftenreihe der Deutschen Vereinigung für Sportwissenschaft, Band 197, pp. 102-10, Feldhaus, Ed. Czwalina


Talks at Conferences and Colloquiums

F. Bauer, U. Römer, A. Fidlin, W. Seemann (2014)
Improving energy efficiency of bipedal robots with elastic couplings.
Dynamic Walking 2014, Zurich, Switzerland

F. Bauer, A. Fidlin, W. Seemann (2013)
Bipedal Robots Walking in Resonance.
Book of Abstracts of the 11th International Conference on Vibration Problems (ICOVP 2013), Lisbon, Portugal

F. Bauer, A. Fidlin, W. Seemann (2013)
Energy Efficient Bipedal Robots Walk in Resonance.
3rd International Conference on Vibro-Impact-Systems and Systems with Non-Smooth Interactions (ICOVIS 2013), Leinsweiler, Germany

F. Bauer, W. Seemann (2011)
A Simple Rigid Body Model for Spatial Running.
Euromech Colloquium 511 - Biomechanics of Human Motion, New Frontiers of Multibody, Techniques for Clinical Applications, Ponta Delgada, Portugal

F. Bauer, W. Seemann (2011)
Dynamics and Stability of Bipedal Locomotion.
3rd French German Workshop on Humanoid & Legged Robots, Paris, France

F. Bauer, W. Seemann (2010)
On the stability of bipedal locomotion.
Thirteenth Conference on Nonlinear Vibrations, Dynamics, and Mulitbody Systems, Virginia Tech, Blacksburg, USA

C. Simonidis, T. Stein, F. Bauer, A. Fischer, H. Schwameder, W. Seemann (2009)
Solving optimal control problems with recursive multibody systems and motion capture to understand the principles of human motion.
Proceedings of the XII International Symposium on Computer Simulation in Biomechanics. Cape Town, South Africa; link to pdf

C. Simonidis, F. Bauer, A. Richter, H. Schwameder, W. Seemann (2009)
Estimation of spinal motion and load for human full-body motion.
Proceedings of the XXII Congress of the International Society of Biomechanics, Cape Town, South Africa; link to pdf

T. Stein, A. Fischer, C. Simonidis, F. Bauer, W. Seemann, H. Schwameder (2009).
The coordination of multi-joint pointing movements in 3D-space.
Book of Abstracts of the 14th annual Congress of the European College of Sport Science in Olso, Norway; link to pdf


Patent Applications

F. Bauer, D. Shelly, K. Wang
DE102009011813A1 Kalibrierwerkzeug für die Fertigung von Tellerfedern. link to pdf
US000008413477B2 Calibration tool for fabricating disk springs. link to pdf