1,720,969 research outputs found
Multi-sensor multi-resolution data fusion modeling
Full text linkInspection analysis of 3D objects has progressed significantly due to the evolution of advanced sensors. Current sensors facilitate surface scanning at high or low resolution levels. In the inspection field, data from multi-resolution sensors have significant advantages over single-scale data. However, most data fusion methods are single-scale and are not suitable in their current form for multi-resolution sensors. Currently the main challenge is to integrate the diverse scanned information into a single geometric hierarchical model. In this work, a new approach for data fusion from multi-resolution sensors is presented. In addition, a correction function for data fusion, based on statistic models, for processing highly dense data (low accuracy) with respect to sparse data (high accuracy) is described. The feasibility of the methods is demonstrated on synthetic data that imitates CMM and laser measurements
Multi-robot spot-welding cells: An integrated approach to cell design and motion planning
Full text linkThe necessity to manage several vehicle models on the same robotized assembly cell has made the cell design and the robot off-line motion planning two fundamental activities. Industrial practice and state-of-the-art methods focus on the technical issues of each activity, but no integrated approach has been yet proposed, resulting in a lack of optimality for the final cell configuration. The paper introduces a formalization of the whole process and proposes a heuristic multi-stage method for the identification of the optimal combination of cell design choices and motion planning. The proposed architecture is depicted through a real case for welding application
Multi-robot spot-welding cells for car-body assembly: Design and motion planning
Full text linkMulti-robot cells for spot welding use coordinated robots to assemble metal panels via spot welding by coordinated robots, for instance in the construction of car doors. The design of multi-robot cells for spot welding required both cell design and off-line motion planning. Cell design involves resource selection (such as robots and welding guns) and resource configuration, while considering cell productivity, costs, flexibility and reconfigurability. Motion planning involves allocating welding points to each resource and calculating collision-free motion plan for each robot. Currently, cell design and motion planning are sequential and manual activities, managed by different and separate industrial functional units. This results in several cycles before the design converges to a feasible final solution. The proposed approach introduces a unified methodology, aiming at optimizing the holistic cell design and motion planning, that reduces design time and errors. The feasibility of the proposed approach has been demonstrated in several ad-hoc basic replicable cases and in one industrial case. The outcome of this research improves state of the art, reducing design and motion planning time over current technology. Moreover, the method has been integrated into a computerized approach which has the potential to accelerate the whole cell design and motion planning processes and to reduce human efforts
Validation of an extended approach to multi-robot cell design and motion planning
Full text linkAccording to both industrial practice and literature, multi-robot cell design and robot motion planning for vehicle spot welding are two sequential activities, managed by different functional units through different software tools. Due to this sequential computation, the whole process suffers from inherent inefficiency. In this work, a new methodology is proposed, that overcomes the above inefficiency through the simultaneous resolution of design and motion planning problems. Specifically, three mathematical models were introduced that (i) select and positions the resources, (ii) allocate the tasks to the resources and (iii) identify a coordinated robot motion plan. Based on the proposed methodology, we built three ad-hoc cases with the goal to highlight the relations between design, motion planning and environment complexity. These cases could be taken as reference cases so on. Moreover, results on an industrial case are presented
Multi-robot spot-welding cell design: Problem formalization and proposed architecture
Full text linkThe multi-robot cell design for car-body spot welding is faced by industry as a sequence of tasks, where researches are focused on issues of the
problem as a whole. In authors’ knowledge, none work in literature have suggested any formalization for the complete process. This paper tries
to bridges the gap proposing coherent process formalization, and presenting a corresponding innovative architecture for the automatic optimal
cell design. Specifically, the formalization involves the identification and allocation of the resources in terms of a set of decisional variables (e.g.
robot model/positioning/number, welding gun models/allocation/number, welding point allocation etc.); then, the design optimization process
minimizes the investment costs granting the cycle time. The multi-loop optimization architecture integrates both new algorithms and existent
procedures from different fields. Test-bed showing its feasibility is reported
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
Design and motion planning of body-in-white assembly cells
Full text linkThis paper proposes a method for the automatic and simultaneous identification of the body-in-white assembly cell design and motion plan. The method solution is based on an iterative algorithm that looks for a global optimum by iteratively identifying the optimum of three sub-problems. These sub-problems concern system layout design and motion planning for single and multi-robot systems, while collision detection is addressed. The sub-problems are handled through ad-hoc developed Mixed Integer Programming (MIP) models. The proposed solution overcomes the limitations of the current design and motion plan approaches. In fact, the design of body-in-white assembly cell and the robot motion planning are two time-expensive and interconnected activities, up to now generally managed from different human operators. The resolution of these two activities as non-interrelated could lead to an increase of the engineer-to-order time and a reduction of the solution quality. Thus, a test bed is described in order to prove the applicability of the approach
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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