1,721,220 research outputs found
Consistent task specification for manipulation systems with general kinematics
No full textAlthough most of the literature on manipulation systems deals with systems with as many degrees of freedom as the dimension of their task space, or even with more (redundant manipulators), kinematically defective manipulation systems are often encountered in robotics, in particular when dealing with simple industry-oriented grippers, or when the whole surface of the manipulator limbs is exploited to constrain the manipulated object, as in "whole-arm" manipulation. Kinematically defective systems differ from nondefective and redundant manipulation systems in many ways, some of which have been addressed in the literature. In this paper, we focus on one of the central problems of manipulation, i.e., controlling the manipulator in order to track a desired object trajectory, while guaranteeing that contact forces are controlled so as to comply with contact constraints (friction bounds, etc.) at every instant. We attack this problem by an unified approach that is appropriate for manipulation systems with general kinematics. When dealing with kinematically defective systems, it is not possible to assign arbitrary trajectories of object motions and contact forces. To understand what restrictions position and force reference trajectories should exhibit in order to be feasible by a given system, is the central issue of this work
Control Problems in Robotics
No full textThis book aims at reporting some of the most challenging open problems of control theoretic nature raised by robotics applications. Topics covered in the book represent many of the most innovative areas in contemporary robotics research, with special emphasis on vision, sensory-feedback control, human-centered robotics, manipulation, planning, flexible and cooperative robots, or assembly systems.
The basic idea behind the book is to present the variety of innovative applications and related technology demands that arise from robotics and automation to a larger community, including in particular, researchers in automatic control, applied mathematics, mechanical engineering, or computer science. The book is intended for an audience of researchers and graduate students in those disciplines and in robotics. It is the outcome of a workshop held in Las Vegas, Nevada on December 14, 2002 jointly sponsored by the IEEE Control Systems Society and the IEEE Robotics and Automation Society
Planning shortest bounded-curvature paths for a class of nonholonomic vehicles among obstacles
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Analysis and optimization of tendinous actuation for biomorphically designed robotic systems
Full text linkWe present a general framework for modeling a class of mechanical systems for robotic manipulation, consisting of articulated limbs with redundant tendinous actuation and unilateral constraints. Such systems, that include biomorphically designed devices, are regarded as a collection of rigid bodies, inter-acting through connections that model both joints and contacts with virtual springs. Methods previously developed for the analysis of force distribution in multiple whole-limb manipulation are generalized to this broader class of mechanisms, and are shown to provide a basis for the control of co-contraction and internal forces that guarantee proper operation of the system. In particular, in the presence of constraints such as those due to limited friction between surfaces or object fragility, the choice of tendon tensions is crucial to the success of manipulation. An algorithm is described that allows to evaluate efficiently setpoints for the control of tendon actuators that "optimally" points for the control of tendon actuators that "optimally" (in a sense to be described) comply with the given constraints
Practical stabilization of discrete-time linear SISO systems under assigned Input and Output quantization
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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