1,721,093 research outputs found
Software Architectures for Mobile Robots
Full text linkA software architecture defines the blueprints of a large computational
system, and is thus a crucial part of the design and development effort. This
task has been explored extensively in the context of mobile robots, resulting
in a plethora of reference designs and implementations. As the software
architecture defines the framework in which all components are implemented, it
is naturally a very important aspect of a mobile robot system. In this chapter,
we overview the requirements that the particular problem domain (a mobile robot
system) imposes on the software framework. We discuss some of the current
design solutions, provide a historical perspective on common frameworks, and
outline directions for future development.Comment: This chapter appears in: Ang, M.H., Khatib, O., Siciliano, B. (eds)
Encyclopedia of Robotics. Springer, Berlin, Heidelber
Sensors for Mobile Robots
Full text linkA sensor is a device that converts a physical parameter or an environmental
characteristic (e.g., temperature, distance, speed, etc.) into a signal that
can be digitally measured and processed to perform specific tasks. Mobile
robots need sensors to measure properties of their environment, thus allowing
for safe navigation, complex perception and corresponding actions, and
effective interactions with other agents that populate it. Sensors used by
mobile robots range from simple tactile sensors, such as bumpers, to complex
vision-based sensors such as structured light RGB-D cameras. All of them
provide a digital output (e.g., a string, a set of values, a matrix, etc.) that
can be processed by the robot's computer. Such output is typically obtained by
discretizing one or more analog electrical signals by using an Analog to
Digital Converter (ADC) included in the sensor. In this chapter we present the
most common sensors used in mobile robotics, providing an introduction to their
taxonomy, basic features, and specifications. The description of the
functionalities and the types of applications follows a bottom-up approach: the
basic principles and components on which the sensors are based are presented
before describing real-world sensors, which are generally based on multiple
technologies and basic devices.Comment: This chapter appears in: Ang, M.H., Khatib, O., Siciliano, B. (eds)
Encyclopedia of Robotics. Springer, Berlin, Heidelber
Implicit Control
Full text linkThis chapter discusses implicit control for robot manipulators. Although the terminology is not homogeneous in the literature, here we assume that an implicit control is a way to control the force arising when the end effector makes contact with the environment, where the force control loop is closed around inner position/velocity loops. As opposed, an explicit control scheme assumes that the output of the force controller is directly in terms of the motion control actuation variables (torques or forces, depending on the nature of the joints)
Feedforward global/inertial sensor fusion algorithm for accurate global positioning of a mobile robot
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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
Characterization of the Subsystems in the General Three-System of Screws
No full textThe chapter examines the subspaces of a space spanned by three twists (or wrenches) with finite pitches and linearly independent directions. The main result is the complete characterization of all cylindroids nested within a general three-system of screws. The findings are illustrated by means of the prestereographic model of three-dimensional projective space, which allows to faithfully represent the screws of a three-system, with their pitches and axis locations, by the surface of a sphere
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
Selection and monitoring of navigation modes for an autonomous rover
No full textConsidering the wide spectrum of situations that it may encounter, a robot navigating autonomously in outdoor environments needs to be endowed with several operating modes, for robustness and efficiency reasons. Indeed, the terrain it has to traverse may be composed of flat or rough areas, low cohesive soils such as sand dunes, concrete road etc... Traversing these various kinds of environment calls for different navigation and/or locomotion functionalities, especially if the robot is endowed with different locomotion abilities, such as the robots WorkPartner, Hylos [4], Nomad or the Marsokhod rovers
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