1,720,973 research outputs found
A mobile platform for haptic grasping in large environments
No full textThis paper presents methodologies and technologies that are exploited to design and implement the mobile haptic grasper (MHG), i.e. an integrated system consisting of a mobile robot and two grounded haptic devices (HD) fixed on it. This system features two-point contact kinaesthetic interactions while guaranteeing full user’s locomotion in large virtual environment. The workspace of haptic interaction is indefinitely extended, and this is extremely relevant for applications such as virtual grasping, where the global workspace is typically reduced with respect to those of the single-point contact devices. Regarding software architecture, we present the Haptik Library, an open source library developed at the University of Siena which allows to uniformly access HD, that has been used to implement the MHG software
Perceptibility of digital watermarking in haptically enabled 3D meshes
No full textUsage of 3D data and models is receiving a growing interest for several applications, like training, museum displays, multimodal interfaces, aid for impaired people. In such a framework the need will soon raise to protect 3D data from misuse. Among the technologies that can be used to this aim, digital watermarking has a prominent role, due to its versatility and non-obtrusiveness. A basic requirement of any watermarking scheme is that the embedded code is invisible, or non-perceivable, by the end user of the data. This requirement also holds for 3D objects, it is then necessary that the human ability of perceiving a signal hidden in a 3D object is studied. In this paper we present a preliminary analysis aiming at comparing the perceptibility of the hidden signal when the 3D model is sensed through different senses, namely vision (through common rendering techniques and subsequent display on a monitor) and touch (through a haptic interface). Specifically our investigation aimed at assessing whether ensuring watermark invisibility is sufficient to ensure that the watermark presence can not be felt haptically. The answer stemming from our preliminary analysis seems to be no, even if further studies are necessary before a definitive answer can be given
Dynamic performance of mobile haptic interfaces
No full textThe increasing demand for virtual reality applications in several scientific disciplines feeds new research perspectives dealing with robotics, automation, and computer science. In this context, one of the topics is the design of advanced force-feedback devices allowing not only kinesthetic interaction with virtual objects but also locomotion and navigation inside virtual worlds. This has the main advantage to stimulate human vestibular apparatus, thus increasing the overall realism of simulation. Particularly, this paper deals with mobile haptic interfaces (MHIs), built by combining standard force-feedback devices with mobile platforms. We investigated which factors may affect the transparency of this kind of devices, identifying in mobile robot dynamics a possible cause of loss of transparency. Hence, in this paper, we present a method to analyze dynamic performance of an MHI and some basic guidelines to design controller in order to meet desired specifications. Experimental validation of the theoretical results is reported. © 2008 IEEE
Conveying Virtual Tactile Feedback Via Augmented Kinesthetic Stimulation
No full textIn real object manipulation, the deformation of the fingerpads along the contact surfaces provides local information about the geometry of the object the subject is manipulating, even in absence of vision and any exploratory movement. In virtual reality with haptic feedback this kind of stimulation is not available because the haptic devices currently available allow to simulate a contact point force interaction thus preventing the deformation of the fingerpads. The aim of this work is that of proposing a novel contact model to augment the information conveyed during kinesthetic interaction with single-point haptic devices. We extended the classic god-point algorithm by using a pseudo-ellipsoidal force field that creates anisotropic compliance in the neighborhood of the contact point. We performed several experiments in order to verify that such contact model can provide information about contact surface orientation even in absence of vision and of free voluntary exploration. The main finding was that participants could identify the orientation of the contact surface when the compliance was maximum in the tangential plane by using small exploratory movements allowed by the penalty-based contact model
Performance of Mobile Haptic Interfaces
No full textOne of most interesting aspects in haptic research deals with the extension of application workspace, thus allowing haptic simulation within large virtual environments. Several devices have been realized that allow this kind of interaction, in particular our interest focuses on mobile haptic interfaces, realized by combining classic grounded haptic devices with mobile platforms. While grounded haptic interfaces feature spatial limitations due to manipulator dimensions, mobile haptic interfaces are characterized by dynamical limitations due to performance of employed devices. In this paper we introduce an experimental analysis to evaluate performance of mobile haptic interface from a transparency standpoint. Moreover, some basic guidelines are presented to enhance MHI performance by setting the controller depending on technical parameters characterizing used devices. © 2005 IEEE
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
Perceptual issues in haptic digital watermarking
No full textThe growing interest in haptic applications suggests that haptic digital media will soon become widely available, and the need will arise to protect digital haptic data from misuse. In this article, we present our study and findings on psychophysical experiments regarding human abilities to perceive a digital watermark, or hidden signal, through a haptic interface
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