1,720,960 research outputs found
Sperimentando con CANbus - Controllo di un motore brushless con ridondandza statica per applicazioni di force-feedback in sistemi steer-by-wire
No full textIn questo articolo viene proposto un approccio Hardware-in-the-Loop (HIL) per la realizzazione di una architettura preliminare di controllo di force feedback in applicazioni Steer-by-Wire (SBW). Come attuatore è stato scelto un motore brushless. La determinazione della posizione dell’albero motore gioca un ruolo chiave nell’algoritmo di controllo.Per ottenere una posizione affidabile dell’albero motore si è scelto di implementare una classica ridondanza statica tripla (TMR – Triple Modular Redundancy). I segnali provenienti dall’encoder integrato nel motore sono stati elaborati sfruttando tre differenti piattaforme HW: la prima basata su microcontrollore a 8-bit, la seconda basata su microcontrollore a 16-bit mentre la terza sfrutta un modulo software integrato nel tool di sviluppo utilizzato come HW virtuale. La piattaforma di HW virtuale è utilizzata anche come voter. La posizione effettiva dell’albero motore, risultato dell’ algoritmo di voting, è inviata via bus CAN alla piattaforma a 16-bit che implementa l’algoritmo di controllo del motore e genera i segnali PWM necessari all’alimentazione del motore.La comunicazione tra HW virtuale e reale avviene attraverso bus CAN. Esperimenti condotti a diverse baudrates confermano la validità dell’algoritmo di voting implementato, che produce risultati corretti anche in caso di guasto in uno dei moduli dell’architettura TMR e non è influenzato da condizioni di alto carico del bus di comunicazione
Control of brushless DC motor with static redundancy for force-feedback in steer-by-wire applications
No full textIn this paper we propose a Hardware-in-the-Loop (HIL) approach to implement a preliminary architecture for force-feedback control in steer-by-wire (SBW) applications. A brushless DC motor (BLDC) is used as force feedback actuator. The determination of the position of the BLDC rotor plays a key role in the control algorithm.To obtain a reliable rotor position a classic triple static redundancy (TMR) is implemented. The position signals from the encoder integrated on the motor are computed in three different ways: using a 8-bit microcontroller, a 16-bit microcontroller, and, last, using the software module integrated in a virtual hardware development tool. The virtual hardware platform operates as voter, too. The position is the output of the voting algorithm and it is sent to the 16-bit platform that controls the motor and provides the correct output PWM signals.The communication between virtual hardware and real hardware uses CAN bus. The bus is monitored by a dedicated development tool. Steer-by-wire is a safety critical application and therefore requires time-triggered protocols. In this preliminary architecture a dedicated network has been implemented and therefore the disadvantages of the event-triggered protocol are considerably reduced.Experiments at different baudrates confirm that the voting algorithm produces correct results also in case of failure in one of the modules of the TMR architecture and it is not conditioned by bus loads. This means that the torque control algorithm of the BLDC motor can generate on the steering wheel (directly connected to the motor) a drive feeling like the one produced by a traditional steering system also in this fail-mode
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
Hardware-in-the-Loop Approach for Redundant Brushless Motor Control System
No full textBrushless motors can be used in a very large range of industrial applications, including force feedback actuators in steer-by-wire systems. Due to the safety critical requirements of this kind of applications, a fault tolerant architecture is needed and it is implemented here using a Hardware-in-the-Loop (HIL) approach.To obtain a reliable control system a classic Triple Modular Redundancy (TMR) architecture has been designed. The very same basic principles to control the motor have been implemented exploiting three different hardware platforms (8-bit, 16-bit and hybrid microcontrollers). All these three hardware modules execute the control algorithm and it will be the voter of the TMR architecture to determine the effective signals (PWM signals) needed to control the motor.This means that redundancy is not limited to the determination of the position of the drive shaft of the motor, but extended to the entire electronic control of the brushless moto
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
- …
