Stable dynamic walking over uneven terrain

  • Authors:

  • Ian R Manchester;Uwe Mettin;Fumiya Iida;Russ Tedrake

  • Affiliations:

  • Computer Science and Artificial Intelligence Lab, Massachusetts Institute of Technology, USA;Department of Engineering Cybernetics, Norwegian University of Science and Technology, Norway;Institute of Robotics and Intelligent Systems, ETH Zurich, Switzerland;Computer Science and Artificial Intelligence Lab, Massachusetts Institute of Technology, USA

  • Venue:
  • International Journal of Robotics Research
  • Year:
  • 2011

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Abstract

We propose a constructive control design for stabilization of non-periodic trajectories of underactuated robots. An important example of such a system is an underactuated 芒聙聹dynamic walking芒聙聺 biped robot traversing rough or uneven terrain. The stabilization problem is inherently challenging due to the nonlinearity, open-loop instability, hybrid (impact) dynamics, and target motions which are not known in advance. The proposed technique is to compute a transverse linearization about the desired motion: a linear impulsive system which locally represents 芒聙聹transversal芒聙聺 dynamics about a target trajectory. This system is then exponentially stabilized using a modified receding-horizon control design, providing exponential orbital stability of the target trajectory of the original nonlinear system. The proposed method is experimentally verified using a compass-gait walker: a two-degree-of-freedom biped with hip actuation but pointed stilt-like feet. The technique is, however, very general and can be applied to a wide variety of hybrid nonlinear systems.