A Policy for Open-Loop Attenuation of Disturbance Effects Caused by Uncertain Ground Properties in Running

Jonathan W. Hurst, Benjamin Morris, Joel Chestnutt, and Alfred Rizzi
IEEE Conference on Robotics and Automation, May, 2007.


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Abstract
Outside of the laboratory, accurate models of ground impact dynamics are either difficult or impossible to obtain. Instead, a rigid ground model is often used in gait and controller design, which simplifies the system model and allows attention to remain focused on other aspects of running. In real-world terrain this simplification may overlook important dynamic effects. Immediately following a foot touchdown event, sensitivity to ground stiffness is at its highest and at the same time the accuracies of state estimates are at their lowest. Even if ground stiffness is known and state estimates are accurate, actuator bandwidth limitations make immediate compensation difficult. Taking inspiration from nature, we propose a novel solution to attenuate the effects of unexpected ground stiffness changes using a unified control system comprised of hardware passive dynamics and open-loop software control policies.

Keywords
running, legged locomotion, series compliance, biped

Notes
Associated Lab(s) / Group(s): Microdynamic Systems Laboratory
Associated Project(s): The Electric Cable Differential (ECD) Leg and Actuator with Mechanically Adjustable Series Compliance

Text Reference
Jonathan W. Hurst, Benjamin Morris, Joel Chestnutt, and Alfred Rizzi, "A Policy for Open-Loop Attenuation of Disturbance Effects Caused by Uncertain Ground Properties in Running," IEEE Conference on Robotics and Automation, May, 2007.

BibTeX Reference
@inproceedings{Hurst_2007_5710,
   author = "Jonathan W Hurst and Benjamin Morris and Joel Chestnutt and Alfred Rizzi",
   title = "A Policy for Open-Loop Attenuation of Disturbance Effects Caused by Uncertain Ground Properties in Running",
   booktitle = "IEEE Conference on Robotics and Automation",
   month = "May",
   year = "2007",
}