1,720,963 research outputs found
Tracking control via switched Integral Sliding Mode with application to robot manipulators
No full textThis paper presents a switching structure scheme for motion control of industrial robot manipulators. To overcome the issues deriving from choosing a priori a specific control scheme, which can result in limited performances when the operating condition of the system varies, the scheme implements both a decentralized approach, suited for lower performance requirements and high transmission ratios, and the inverse dynamics based centralized approach, suited for higher performances in terms of velocity and acceleration. In both cases, the Integral Sliding Mode algorithm is used to compensate matched disturbances and to estimate the unmodeled dynamics used for the switching decision mechanism
A Configuration Space Reference Generation Approach for Real-Time Collision Avoidance of Industrial Robot Manipulators
No full textIn this work a novel approach for target reaching and collision avoidance in industrial robot manipulators is proposed. This method solely relies on the computation of the direct kinematics of the considered industrial manipulator in order to generate joint reference positions to perform real-time tracking in the operative space and avoidance of obstacles moving in the proximity of the robot. A comparison with a conventional model-based collision avoidance method has been carried out in a simulated industrial setting under different conditions, showing satisfactory results even in case of coarse sampling times. This makes the proposal suitable for filed real-time operations executed by industrial robots performing a task. The proposed approach has been deployed on the EPSON VT6 6-axis industrial manipulator, whose proprietary software has been interfaced with general-purpose robotic simulators in order to emulate complex and dynamic environments
Sliding mode fault diagnosis with vision in the loop for robot manipulators
No full textThis chapter is devoted to the problem of Fault Diagnosis (FD) for industrial robotic manipulators within the framework of sliding mode control theory. According to this control concept, a set of unknown input higher order sliding mode observers are designed to detect, isolate and identify multiple actuators faults and corruptions. More specifically, the whole FD architecture is based on the inverse dynamics-based feedback linearized robotic MIMO system, which is equivalent to a set of linearized decoupled SISO systems, affected by uncertain terms. The FD process includes a residual generation, followed by a decision making through the evaluation of the achieved residuals. The advantages of the sliding mode approach are the good performance in terms of stability and robustness, as well as satisfactory estimate of the occurring faults. Furthermore, in order to extend the FD strategy to multiple sensor and actuator faults, a low cost vision servoing architecture is used in the scheme, allowing one to design a fault tolerant control strategy in case of sensor faults. The effectiveness of the proposed FD architecture has been carried out in simulation on a realistic simulator as well as experimentally on a COMAU SMART3-S2 anthropomorphic robot manipulator
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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