1,720,990 research outputs found
On some geometric control properties of active suspensions systems.
Full text linkThe geometric control properties of vehicles with active suspensions are analyzed. A special attention is devoted to the problem of disturbance decoupling. Active suspensions of advanced vehicles allow the active rejection of external disturbances exerted on the sprung mass of the vehicle and caused by road surface irregularity. We focus on the road irregularity disturbances with the purpose of isolating the chassis from vibrations transmitted through suspensions. The paper is aimed at the synthesis of a decoupling control law of the regulated outputs, i. e., roll, pitch and chassis height, from the external disturbances. The paper emphasizes that disturbance decoupling can be thought as a structural property of road vehicles with active suspensions. The framework throughout is the geometric approach to the control of dynamic systems. It is shown that a controlled and conditioned invariant subspace exists such that it allows the geometric disturbance localization. The decoupling problem with stability and the algebraic feedback of suspension heights, i. e. the system measurements, are considered. Simulations with real data are included to validate theoretical results. Saturating actuators are also considered in order to model a more realistic case
Geometric control tools for robotic manipulators
No full textThis paper investigates the geometric and structural characteristics involved in the control of rather general manipulation systems, consisting of multiple cooperating link-
ages, interacting with a reference member of the mechanism (the \object") by means of contacts on any available
part of their links. Object grasp and manipulation by the human hand is taken as a paradigmatic example for this class of manipulators. This paper reports on some recent results on the analysis and control of these mechanisms, based on a geometric analysis of a local approximation of system dynamics. A special attention is devoted to the force control by an algebraic output feedback
Locomotive drive control by using Haar Wavelets Packets
No full textPreliminary simulations and roughly algorithms show how the use of wavelet packets are very promising in itermodulation disturbance rejection for converter bridge control. The presented contribution wants to pay attention on an original way to states a possible converter bridge control by using Haar wavelet packets. The presented attack to the problem could represent a possible alternative to the traditional PWM control for the converter bridge. The idea is to find an algorithm which guaranties the needed
power supply and in the meantime a high level of the S ratio. One proposes a roughly algorithm N which find the length of the active switching function looking for suitable scaling function. The open problem consists of checking the suitability of its formulation in order to build a rigorous algorithm which can find a switching control law
Active suspensions decoupling by algebraic feedback
No full textActive suspensions of advanced vehicles allows the active rejection of external disturbances exerted directly on the sprung mass of the vehicle and due to the road surface irregularity. We focus on the road irregularity disturbances with the purpose of isolating the chassis from vibrations transmitted through suspensions. The paper is aimed at the synthesis of a decoupling control law of the regulated outputs, i.e., roll, pitch and chassis height, from the external disturbances. The framework throughout is the geometric approach to the control of dynamic systems. It will be shown that a controlled and conditioned invariant subspace exists and this allows the perfect disturbance localization by feeding back the suspensions heights
Geometric control techniques for manipulation systems
No full textThe control of robotic manipulation is investigated. Manipulation systemanalysis and control are approached in a general framework. The geometric aspectof manipulation system dynamics is strongly emphasized by using the well developedtechniques of geometric multivariable control theory. The focus is on the control ofthe crucial outputs in robotic manipulation, namely the reachable internal forces andthe rigid{body object motions. A state{feedback control procedure is outlined fordecoupling these outputs and nally special attention is devoted to the synthesis ofthe state observer
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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