Robotic Manipulation with Flexible Link Fingers
Sudipto Sur
PhD Dissertation, Caltech, January 1997
Robots with structural flexibility provide an attractive alternative
to rigid robots for many of the new and evolving applications in
robotics. In certain applications their use is unavoidable. The
increased complexity in modeling and control of such robots is offset
by desirable performance enhancements in some respects. In this thesis
we present a singular perturbation approach for modeling, analysis and
control of robots with flexibility. As our singular perturbation
approach does not treat the flexible manipulator as a perturbation of
the rigid manipulator, it can treat significant flexibility, beyond
the linear range. Analysis based on this approach leads to some
provably stable control laws for the hybrid position and force control
of flexible-link manipulators. The analysis is done in the framework
of a single robot manipulator in a constrained motion
task. Simulations and experimental results are presented for this
case. To show applicability of the results to more general and
complex systems with flexibilities we also present experimental data
from a planar, two-fingered, reconfigurable grasping setup which allows
rigid and flexible configurations. The aim of the experimentation is
to show the applicability of the control laws and analysis developed,
and to determine the performance enhancements resulting from the
introduction of flexibility. Experimental data is analysed to show the
tradeoffs between controller complexity and performance enhancement as
we deal with greater flexibility. Various performance criteria are set
up and experimental results are discussed within their framework. We
conclude that large flexibility can be controlled without too much
additional effort, has performance comparable to that of rigid robots,
and possesses enhancing properties which make it appealing for use in
certain types of applications.
PhD Dissertation
(PDF, 11673K, 143 pages)
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Richard Murray (murray@cds.caltech.edu)