| Volume 27 Issue 3-4 - Publication Date: 1 March 2008 |
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| Distributed Control Architecture for Self-reconfigurable Manipulators |
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| A. Turetta, G. Casalino and A. Sorbara
DIST – University of Genova, Via Opera Pia 13, 16145 Genova, Italy |
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| In recent years self-reconfigurable modular robots have gained increasing
interest from part of the international robotic community.
Although recent robots of this type are characterized by advanced
electro-mechanical designs, the development of their supporting control
techniques have only registered strong results in the field of locomotion
problems, while the manipulation capabilities of existing
systems still appear to be quite limited. Aiming to provide a contribution
along this latter direction, in this paper we propose a computationally
distributed technique for controlling the motion of any
tree-structured chain resulting from reconfiguration in its operational
space. The presented strategy, which could actually be adopted when
dealing with any kind of chain-based modular robotic system, turns
out to be particularly well suited to self-reconfigurable structures for
three main reasons: (i) it is not based on any explicit role assignment;
all of the modules can be added, removed or exchanged online as required,
with no impact on the overall control architecture; (ii) each
module has only a very limited set of local information that must be
known a priori and can be totally unaware of the remaining part of
the chain; (iii) no external centralized controller is necessary; basic
local processing and communication units onboard every module
and a simple man–machine interface providing high-level commands
are enough. A global self-coordinating behavior is automatically exhibited
by the proposed technique at power-on or immediately after
any configuration change as the result of a number of repeated data
exchanges, performed online along the chain at every sampling interval.
Although achievable performances depend on the available
communication bandwidth, the convergence towards a final position
error of zero is, however, always guaranteed. Moreover, because the
computational burden required by every module is extremely light,
the proposed technique represents an effective control solution that
can be easily implemented onboard many of the low-cost and small
control platforms available on existing self-reconfigurable robots. |
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| Multimedia Key |
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 = Data |
= Code |
= Image |
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Extension |
Type |
Description |
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1 |
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Example
1: Simulation of a modular manipulator
with eight degrees of freedom executing a
point-to-point motion task while performing
a varying number of iterations. (12.2 MB) wmv |
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2 |
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Example
2: Simulation of a modular manipulator
with eight degrees of freedom moving in
the presence of a joint limit. (2 MB) wmv |
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3 |
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Example
3: Simulation of a tree-structured modular
manipulator with 20 degrees of freedom
executing a point-to-point movement. (6.4 MB) wmv |
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4 |
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Example
4: Simulation of a tree-structured modular
manipulator with 20 degrees of freedom
performing a docking maneuver. (5.5 MB) wmv |
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5 |
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Example
5: P2MR: first-generation modules. (17 MB) wmv |
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6 |
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Example
6: P2MR: different configurations obtainable
by second-generation modules. (13.7 MB) wmv |
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7 |
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Example
7: P2MR: movement along the edges of a
rectangle. (14 MB) wmv |
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