1,721,053 research outputs found
An Approach for Multi-Robot Opportunistic Coexistence in Shared Space
No full textThis thesis considers a situation in which multiple robots operate in the
same environment towards the achievement of different tasks. In this situation,
please consider that not only the tasks, but also the robots themselves
are likely be heterogeneous, i.e., different from each other in their
morphology, dynamics, sensors, capabilities, etc. As an example, think
about a "smart hotel": small wheeled robots are likely to be devoted to
cleaning floors, whereas a humanoid robot may be devoted to social interaction,
e.g., welcoming guests and providing relevant information to
them upon request.
Under these conditions, robots are required not only to co-exist, but also
to coordinate their activity if we want them to exhibit a coherent and
effective behavior: this may range from mutual avoidance to avoid collisions,
to a more explicit coordinated behavior, e.g., task assignment or
cooperative localization.
The issues above have been deeply investigated in the Literature. Among
the topics that may play a crucial role to design a successful system, this
thesis focuses on the following ones:
(i) An integrated approach for path following and obstacle avoidance is
applied to unicycle type robots, by extending an existing algorithm [1]
initially developed for the single robot case to the multi-robot domain.
The approach is based on the definition of the path to be followed as a
curve f (x;y) in space, while obstacles are modeled as Gaussian functions
that modify the original function, generating a resulting safe path. The
attractiveness of this methodology which makes it look very simple, is
that it neither requires the computation of a projection of the robot position
on the path, nor does it need to consider a moving virtual target
to be tracked. The performance of the proposed approach is analyzed
by means of a series of experiments performed in dynamic environments
with unicycle-type robots by integrating and determining the position of
robot using odometry and in Motion capturing environment.
(ii) We investigate the problem of multi-robot cooperative localization
in dynamic environments. Specifically, we propose an approach where
wheeled robots are localized using the monocular camera embedded in
the head of a Pepper humanoid robot, to the end of minimizing deviations
from their paths and avoiding each other during navigation tasks.
Indeed, position estimation requires obtaining a linear relationship between
points in the image and points in the world frame: to this end, an
Inverse Perspective mapping (IPM) approach has been adopted to transform
the acquired image into a bird eye view of the environment. The
scenario is made more complex by the fact that Pepper’s head is moving
dynamically while tracking the wheeled robots, which requires to consider
a different IPM transformation matrix whenever the attitude (Pitch
and Yaw) of the camera changes. Finally, the IPM position estimate returned
by Pepper is merged with the estimate returned by the odometry
of the wheeled robots through an Extened Kalman Filter. Experiments
are shown with multiple robots moving along different paths in a shared
space, by avoiding each other without onboard sensors, i.e., by relying
only on mutual positioning information.
Software for implementing the theoretical models described above have
been developed in ROS, and validated by performing real experiments
with two types of robots, namely: (i) a unicycle wheeled Roomba robot(commercially available all over the world), (ii) Pepper Humanoid robot
(commercially available in Japan and B2B model in Europe)
Sparse Identification of Nonlinear Dynamics for Delay and Stochastic Differential Equations
No full textRecently, data-driven model discovery has emerged has a powerful approach to recover governing equations of dynamical systems from temporal data series [3]. In particular, the SINDy algorithm, initially proposed for learning the right-hand side of ordinary differential equations [4], has been extended and applied to diverse classes of problems, including delay differential equations [2, 5] and stochastic (ordinary) differential equations [1]. In this talk we present a further development by proposing a new SINDy algorithm to address the case of stochastic delay differential equations. The relevant MATLAB implementation is tested on several examples, including stochastic models with delay used to describe and investigate supply chains
Collision-free navigation of multiple unicycle mobile robots
No full textWheeled Robots (WRs) are widely used in many different contexts, and usually they are required to operate in partial or total autonomy. In particular, in a wide range of situations, having the capability of following a predetermined path and avoiding unexpected obstacles can be extremely relevant. On these basis, this paper analyzes an integrated approach for path following and obstacle avoidance applied to unicycletype robots. The approach is based on the definition of the path to be followed as a curve f(x, y) in space, while obstacles are modeled as Gaussian functions that modify the original function, generating a resulting safe path. The attractiveness of this methodology which makes it look very simple, is that it neither requires the computation of a projection of the robot position on the path, nor does it need to consider a moving virtual target to be tracked. The performances of the proposed approach are analyzed by means of a series of experiments performed in dynamic environments with unicycle-Type robots
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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