February 15, 2015 / by George Council / In news

Bifurcation and chaos in the simple passive dynamic walking model with upper body

We present some rich new complex gaits in the simple walking model with upper body by Wisse et al. We first show that the stable gait found by Wisse et al. may become chaotic via period-doubling bifurcations.

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February 15, 2015 / by George Council / In news

Rigorous Enclosures of a Slow Manifold

Slow-fast dynamical systems have two time scales and an explicit parameter representing the ratio of these time scales. Locally invariant slow manifolds along which motion occurs on the slow time scale are a prominent feature of slow-fast systems. This paper introduces a rigorous numerical method to compute enclosures of the slow manifold of a slow-fast system with one fast and two slow variables.

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February 05, 2015 / by George Council / In booklist

A direct method for Trajectory Optimization of Rigid Bodies Through Contact

A paper about trajectory optimization in hybrid systems. Interesting, as it relaxes would be naively been consider a core constraint of hybrid systems - the order at which vector fields are switched through. While specific for a rigid body, it provides a scablable numerical tool to optimizie over the 'aggregate' dynamics, rather than find optimal solutions in each vector field with a known ordering

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February 05, 2015 / by George Council / In news

Preparing the leg for ground contact in running - the contribution of feed-forward and visual feedback

A paper, among many, that explores the usage of feedforward control in perserving periodic gaits in SLIP-like models. As the lab has contributed to this discussion in a very general way, it is useful to examine other groups' special-case result to see if our result encompasses it, or it is an novel technique. Interestingly, this paper consists of experiemental measurements of acutal muscle activity in moving humans - suggesting that feedforward muscle activity is sufficient to explain previously observed feed-forward leg adjustments.

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