1,720,971 research outputs found
Programming real-time sound in Python
Full text linkFor its versatility, Python has become one of the most popular programming languages. In spite of its possibility to straightforwardly link native code with powerful libraries for scientific computing, the use of Python for real-time sound applications development is often neglected in favor of alternative programming languages, which are tailored to the digital music domain. This article introduces Python as a real-time software programming tool to interested readers, including Python developers who are new to the real time or, conversely, sound programmers who have not yet taken this language into consideration. Cython and Numba are proposed as libraries supporting agile development of efficient software running at machine level. Moreover, it is shown that refactoring few critical parts of the program under these libraries can dramatically improve the performances of a sound algorithm. Such improvements can be directly benchmarked within Python, thanks to the existence of appropriate code parsing resources. After introducing a simple sound processing example, two algorithms that are known from the literature are coded to show how Python can be effectively employed to program sound software. Finally, issues of efficiency are mainly discussed in terms of latency of the resulting applications. Overall, such issues suggest that the use of real-time Python should be limited to the prototyping phase, where the benefits of language flexibility prevail on low latency requirements, for instance, needed during computer music live performances
An open-source robotic tool for the simulation of quasi-static finger pressing on stationary and vibrating surfaces
Full text linkThe Bogus Finger is a remote-controllable tool for simulating vertical pressing forces of various magnitude as exerted by a human finger. Its main application is the characterization of haptic devices under realistic active touch conditions. The device is released as an open-source hardware and software DIY project that can be easily built using off-the-shelf components. We report the characterization of the quasi-static properties of the device, and validate its dynamic response to pressing on a vibrating surface by comparison with human fingers. The present prototype configuration accurately reproduces the mechanical impedance of the human finger in the frequency range 200-400 Hz
Endless Knob with Programmable Resistive Force Feedback
No full textTouchscreens today represent the most versatile solution for configuring user interfaces. A toll for this versatility is the intangibility of the displayed virtual controls. The addition of haptic feedback can improve their manipulation by reinforcing or even substituting visual information. While haptic rendering of virtual buttons is advancing, tangible knobs seem yet to come, possibly due to the inherent difficulty to conceptualize rotation as an interaction primitive in absence of a physical control. To address this issue, we propose a hybrid solution consisting in an endless knob with programmable resistance to rotation. Compared to existing related devices, it minimizes costs, encumbrance and power consumption, making its installation also possible on portable equipment. After describing its design and main features, we present a test which assessed how haptic feedback rendered by the knob affects performance in a visual target-matching task: users had to select targets placed on a horizontal slider by dragging its cursor through knob rotation. Results show that haptic augmentation significantly improved target acquisition
Does It Ping or Pong? Auditory and Tactile Classification of Materials by Bouncing Events
Full text linkTwo experiments studied the role of impact sounds and vibrations in classification of materials. The task consisted of feeling on an actuated surface and listening through headphones to the recorded feedback of a ping-pong ball hitting three flat objects respectively made of wood, plastic, and metal, and then identifying their material. In Experiment 1, sounds and vibrations were recorded by keeping the objects in mechanical isolation. In Experiment 2, recordings were taken while the same objects stood on a table, causing their resonances to fade faster due to mechanical coupling with the support. A control experiment, where participants listened to and touched the real objects in mechanical isolation, showed high accuracy of classification from either sounds (90% correct) or vibrations (67% correct). Classification of reproduced bounces in Experiments 1 and 2 was less precise. In both experiments, the main effect of material was statistically significant; conversely, the main effect of modality (auditory or tactile) was significant only in the control. Identification of plastic and especially metal was less accurate in Experiment 2, suggesting that participants, when possible, classified materials by longer resonance tails. Audio-tactile summation of classification accuracy was found, suggesting that multisensory integration influences the perception of materials. Such results have prospective application to the nonvisual design of virtual buttons, which is the object of our current research
Modulating the Perceived Softness of Real Objects Through Wearable Haptics
No full text: in vision, augmented reality (AR) allows the superposition of digital content on real-world visual information, relying on the well-established see-through paradigm. In the haptic domain, a putative Feel-through wearable device should allow to modify the tactile sensation without masking the actual cutaneous perception of the physical objects. To the best of our knowledge, a similar technology is still far to be effectively implemented. In this work, we present an approach that allows, for the first time, to modulate the perceived softness of real objects using a feel-through wearable that uses a thin fabric as interaction surface. during the interaction with real objects, the device can modulate the growth of the contact area over the fingerpad without affecting the force experienced by the user, thus modulating the perceived softness. To this aim, the lifting mechanism of our system warps the fabric around the fingerpad in a way proportional to the force exerted on the specimen under exploration. at the same time, the stretching state of the fabric is controlled to keep a loose contact with the fingerpad. We demonstrated that different softness perceptions for the same specimens can be elicited, by suitably controlling the lifting mechanism of the system
Evaluation of rotation gestures in rotary vs. motionless knobs
Full text linkIn environments where knobs are frequently damaged by mechanical wear or seepage of liquids, the use of sealed substitutes without moving parts has been tested. In this case, users slide their fingers around a still cylinder rather than rotating a knob. A comparative experiment is reported in this paper, in which participants were asked to perform rotation gestures by specific angles on either a rotary or motionless knob, both hidden to sight. Concerning rotation performance, no significant differences were measured in terms of mean accuracy and precision; however, sliding caused larger deviations in the final position of the fingers. In parallel, a questionnaire unveiled issues of affordability of the motionless knob. Our experiment is preliminary to the realization and validation of a haptic rotation sensing technology applicable to graspable motionless cylinders
Flipping food during grilling tasks, a dataset of utensils kinematics and dynamics, food pose and subject gaze
Full text linkThis paper presents a multivariate dataset of 2866 food flipping movements, performed by 4 chefs and 5 home cooks, with different grilled food and two utensils (spatula and tweezers). The 3D trajectories of strategic points in the utensils were tracked using optoelectronic motion capture. The pinching force of the tweezers, the bending force and torsion torque of the spatula were also recorded, as well as videos and the subject gaze. These data were collected using a custom experimental setup that allowed the execution of flipping movements with freshly cooked food, without having the sensors near the dangerous cooking area. Complementary, the 2D position of food was computed from the videos. The action of flipping food is, indeed, gaining the attention of both researchers and manufacturers of foodservice technology. The reported dataset contains valuable measurements (1) to characterize and model flipping movements as performed by humans, (2) to develop bio-inspired methods to control a cooking robot, or (3) to study new algorithms for human actions recognition
Toward the manipulation of time and space in extended reality: a preliminary study on multimodal Tau and Kappa illusions in the visual-tactile domain
Full text linkIn the last few years, Extended reality (XR) has enabled novel forms of sensory experiences and social interplay, which can be hardly experienced in real life. However, the full potential of XR has not been exploited yet, since vision remains the main interaction modality, and the time-and space-modulation of the sense of self-which could open interesting perspectives in several scenarios-is still largely unexplored. To pave the path to a multi-modal manipulation of the sense of time and space in immersive XR, in this work we discuss the preliminary outcomes of the first investigation in the visual-tactile domain of two well known perceptual illusions affecting spatial and temporal perception, i.e. Tau and Kappa effects, respectively. We compared the effects originated from unimodal stimulation (i.e., only visual or tactile) with the same effects induced by convergent bimodal stimulation (i.e., visual and tactile), delivered to the forearm. Results show that both Tau and Kappa effects are affected by the multi-modality of the stimulation, and that the perceptual bias differently affects time-or space-perception based on the modality used for stimulus delivery. Our results, although preliminary, seem to suggest that multimodal perceptual illusions could be a viable solution for time-and space-modulation of the sense of self in immersive XR and advanced social human-robot interaction
Effects of vibration direction and pressing force on finger vibrotactile perception and force control
Full text linkThis paper reports about the effects of vibration direction and finger-pressing force on vibrotactile perception, with the goal of improving the effectiveness of haptic feedback on interactive surfaces. An experiment was conducted to assess the sensitivity to normal or tangential vibration at 250 Hz of a finger exerting constant pressing forces of 0.5 or 4.9 N. Results show that perception thresholds for normal vibration depend on the applied pressing force, significantly decreasing for the stronger force level. Conversely, perception thresholds for tangential vibrations are independent of the applied force, and approximately equal the lowest thresholds measured for normal vibration
Encoding manual rotations on a motionless knob
Full text linkDespite the robustness and versatility of touchscreens affording haptic rotation, physical knobs remain widely adopted in the control layout of professional machines and appliances. Their low cost, established design, and efficiency in encoding rotations – even when an operator's attention is focused elsewhere – make them an optimal choice. However, physical knobs are often prone to electro-mechanical damage in settings such as food or cleaning service facilities. To overcome potential consequent safety and productivity issues, we have designed and prototyped a motionless cylindrical device capable of encoding manual rotation. The device tracks finger contact positions on its lateral surface through capacitive sensing, which are then processed by a neural network-based encoding algorithm designed to classify manual rotations in real-time on low-cost embedded hardware. A user test evaluating manual rotation confirmed accuracy in line with a previous experiment conducted on a motionless knob. In parallel, a decrease in precision was observed, possibly as a consequence of the sensing technology and encoding algorithm. Subjective questionnaires assessing specific aspects of the interaction quality with the prototype reinforced previous findings, suggesting that achieving natural and intuitive gestures on a motionless knob requires adaptation of a deeply embodied interaction primitive such as manual rotatio
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