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We consider planning and control problems for underactuated manipulators, a special instance of mechanical systems having fewer input commands than degrees of freedom. This class includes robots with passive joints, elastic joints, or flexible links. Structural control properties are investigated, showing that manipulators with passive joints in the absence(More)
We study the problem of computing an exact motion plan for the snakeboard, an underactuated system subject to nonholonomic constraints, by exploiting its kinematic controllability properties and its decoupling vector fields. Decoupling vector fields allow us to plan motions for the underactuated dynamic system as if it were kinematic, and rest-to-rest paths(More)
We consider the problem of trajectory planning and control for an XYnR ¯ planar robot with the first two joints (rotational or prismatic) actuated and n rotational passive joints, moving both in the presence and the absence of gravity. Under the assumption that each passive link is attached at the center of percussion of the previous passive link, dynamics(More)
SUMMARY Cryptography is the most suitable technique to protect the access to subscribed value-added services for mobile applications provided through satellite broadcasting (e.g. localization and mobile TV). However, if a temporary loss of signal is experienced by receivers, not only the data streaming is compromised, but also the key management-related(More)
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