The problem of performing complex maneuvers in challenging terrains
is crucial to the advancement of legged robots and
assistive devices, yet little progress has been made in exploring practical
solutions to operate in these environments. In this thesis, we tackle the
problem by developing strategies to predict a robot's center of mass (CoM)
behavior based on contact constraints, and any arbitrary CoM path for
situations in which the system has single or multiple points of contact through which external
reaction forces may be applied. Our method consists of first leveraging
previous work on multi-contact dynamics to derive reaction force
behavior from internal tension force profiles and kinematic CoM trajectories.
We then study the nonlinear dynamics of
single contact phases along arbitrary paths and employ numerical
integration to derive state-space approximations of CoM behavior.
We use this theoretical framework to synthesize complex
maneuvers in various terrains by means of a motion planner in which
we determine step transition sequences for continuous motions involving contact
profiles which vary with time.
Furthermore, we validate our strategy through several comparative case studies,
examining the motion of a human subject performing a difficult
maneuver in an aggressive terrain. We then seed our motion planning algorithm with
a limited set of parameters chosen to match those of a human subject and predict CoM behavior
for the same motion pattern. These case studies show
that the estimated CoM behaviors generated from our planning algorithm
closely resemble the behavior of the human subject and therefore validate our methods. / text
| Identifer | oai:union.ndltd.org:UTEXAS/oai:repositories.lib.utexas.edu:2152/ETD-UT-2012-05-5619 |
| Date | 26 July 2012 |
| Creators | Slovich, Michael |
| Source Sets | University of Texas |
| Language | English |
| Detected Language | English |
| Type | thesis |
| Format | application/pdf |
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