Ruprecht-Karls-Universität Heidelberg
Optimization in Robotics and Biomechanics

HeiLe - Heidelberg Legged Robot: Design and optimization of a stable running robot

Katja Mombaur, Johannes Schlöder, Andreas Reischmann - IWR
Tillmann Lang, Simon Friedmann - former IWR members

The purpose of our research is to show how the control of fast dynamic walking and running robots can be simplified using mathematical models of the robot and trajectories generated by optimization.

For this purpose, we use the bipedal robot HeiLe (Heidelberg Legged robot) which has been built for us by the company Tetra in Illmenau.

It has a horizontal trunk and two telescopic legs which can swing back and forth. It has seven degrees of freedom and moves in the vertical plane, where sideward motions are eprevented by two glass plates. The robot motions are powered by four DC motors in the hip joints and in te legs. In addition to the free choice of input histories to its motors, the robot platform allows tuning of several design parameters such as spring constants, lengths of several segments etc.

Following the tradition of (passive-)dynamic walking robots, our approach is to look for stable limit cycles of the robotic system. If given the right configuration and actuator inputs, many systems can exhibit stable limit cycles - in other words: open-loop stable motions - which means that they would automatically recover from small perturbations and converge back to the periodic orbit without any feedback corrections at all

We have previously presented a numerical approach to determine open-loop stable configurations and motions for very general systems and used it to produce stable limit cycles for a similar bipedal pogo-leg models and a variety of motions (run, hop, somersault, flip-flops), click here for more details.

The purpose of this project is to validate the approach in close interaction of computations and experiments for a specific robot.

In order to perform stability optimization runs, a detailed model of the robot is required. The first part of this project consisted in establishing the robot model and identiyfing the correct model parameters using numerical techniques.


References:

T. Lang, K. Mombaur, S. Friedmann, J. Schlöder: Modeling and Optimal Control of a Pogo-Leg Running Robot, Proceedings of CLAWAR 2009, Istanbul, Sept. 2009

T. Lang: Optimierungsbasierte Modellierung des zweibeinigen dynamischen Laufroboters HEILE, Diploma Thesis, IWR, University of Heidelberg


K. Mombaur, orb@uni-hd.de
Last Update: 19.10.2011 - 16:03

The photographs in the header of this webpage have been taken at the Musee de l'Automate in Souillac, France