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 National Science
Foundation Award #0546430 |
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CAREER: Planning and Control for Overconstrained Mechanisms |
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| Investigator(s): |
Todd Murphey (PI)
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| Sponsor: |
University of Colorado at Boulder, CO 80309 3034926221
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| Start Date/Expiration Date |
2006-02-15 to 2011-01-31 (amended 2006-02-10) |
| Awarded Amount to Date: |
$400,000 |
| Abstract: Abstract
Multiple point contact is common in many manipulation tasks. Examples
include arrays for distributed or micro manipulation, vehicles, and
traditional robotic grasping. Although all of these applications have
received a great deal of attention, no previous works have provided an
analytical approach capable of dealing with the inherent uncertainties in
the contact state--the state that represents whether a given contact is
sticking, slipping, or is out of contact. These nonsmooth transitions
between contact states have a dramatic impact on the dynamics; hence, it
is important to systematically mitigate the negative performance these
nonsmooth effects induce. Moreover, these systems are often overactuated,
so that each contact interface is independently articulated. This leads
to mechanisms that are nominally kinematically overconstrained--that is,
the kinematic relationships between all the point contacts cannot be
simultaneously satisfied. Which constraint is broken is sensitive to
details of friction and normal force modeling, so it is necessary to
estimate the current contact state and incorporate the contact state into
the motion planning and control. The goal of this research is to
produce hybrid estimators, motion planning algorithms, and control
strategies that will work in concert to guarantee performance and
stability in the face of multiple contact interfaces in an unstructured
environment. An overconstrained multiple point manipulator prototype will
be developed and planning and control methods will be applied to this
system to demonstrate manipulation that is not sensitive to the
particulars of the frictional interfaces.
Manufacturing often involves the need to reposition and reorient objects
for purposes of assembly. To accomplish this, multiple actuators are
often used, and these actuators experience stick and slip contact with the
object due to frictional interactions. The physics of the actuators and,
in particular, their interaction with the object are notoriously difficult
to model accurately. Hence, there is a strong need for manipulation
strategies that are not sensitive to these low-level details. Moreover,
many vehicles, such as the original Mars rover, have a mechanical design
that guarantees that some of the wheels must slip during operation.
However, which wheels slip is dependent on unknown environmental conditions. Hence, in this situation as well there is a need to develop motion planning strategies that are guaranteed to work even in the presence of substantial uncertainty arising from the environment. This project will contribute to these needs by developing
strategies that have guaranteed performance in the face of inherent
uncertainty. In the short term this project will contribute to macro-scale
manufacturing and vehicle control, and in the long-term will likely impact
micro-scale manufacturing. |
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| NSF Org: |
CMS - Division of Civil and Mechanical Systems |
| Award Number: |
0546430 |
| Award Instrument: |
Standard Grant |
| Program Manager: |
Mario A. Rotea
CMS Division of Civil and Mechanical Systems
ENG Directorate for Engineering
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| NSF Program(s): |
CONTROL SYSTEMS PROGRAM |
| Field Application(s): |
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| Program Reference Code(s): |
FACULTY EARLY CAREER DEVELOPMENT PROGRAM, 1045
PECASE- eligible, 1187
UNASSIGNED, 0000
CONTROL SYSTEMS, 030E |
| Program Element Code(s): |
1632 |
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