An open-source robotic tool for the simulation of quasi-static finger pressing on stationary and vibrating surfaces

The 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

Effects of vibration direction and pressing force on finger vibrotactile perception and force control

This 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

Tactile discrimination of material properties: application to virtual buttons for professional appliances

An experiment is described that tested the possibility to classify wooden, plastic, and metallic objects based on reproduced auditory and vibrotactile stimuli. The results show that recognition rates are considerably above chance level with either unimodal auditory or vibrotactile feedback. Supported by those findings, the possibility to render virtual buttons for professional appliances with different tactile properties was tested. To this end, a touchscreen device was provided with various types of vibrotactile feedback in response to the sensed pressing force and location of a finger. Different virtual buttons designs were tested by user panels who performed a subjective evaluation on perceived tactile properties and materials. In a first implementation, virtual buttons were designed reproducing the vibration recordings of real materials used in the classification experiment: mainly due to hardware limitations of our prototype and the consequent impossibility to render complex vibratory signals, this approach did not prove successful. A second implementation was then optimized for the device capabilities, moreover introducing surface compliance effects and button release cues: the new design led to generally high quality ratings, clear discrimination of different buttons and unambiguous material classification. The lesson learned was that various material and physical properties of virtual buttons can be successfully rendered by characteristic frequency and decay cues if correctly reproduced by the device

BIVIB: A Multimodal Piano Sample Library Of Binaural Sounds And Keyboard Vibrations

An extensive piano sample library consisting of binaural sounds and keyboard vibration signals is made available through an openaccess data repository. Samples were acquired with high-quality audio and vibration measurement equipment on two Yamaha Disklavier pianos (one grand and one upright model) by means of computer-controlled playback of each key at ten different MIDI velocity values. The nominal specifications of the equipment used in the acquisition chain are reported in a companion document, allowing researchers to calculate physical quantities (e.g., acoustic pressure, vibration acceleration) from the recordings. Also, project files are provided for straightforward playback in a free software sampler available for Windows and Mac OS systems. The library is especially suited for acoustic and vibration research on the piano, as well as for research on multimodal interaction with musical instruments

Does It Ping or Pong? Auditory and Tactile Classification of Materials by Bouncing Events

Two 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

Respiratory muscle training in patients recovering recent open cardio-thoracic surgery: a randomized-controlled trial.

Objectives- To evaluate the clinical efficacy and feasibility of an expiratory muscle training (EMT) device (Respilift™) applied to patients recovering from recent open cardio-thoracic surgery (CTS). Design- Prospective, double-blind, 14-day randomised-controlled trial. Participants and setting- 60 inpatients recovering from recent CTS and early admitted to a pulmonary rehabilitation program. Interventions- Chest physiotherapy plus EMT with a resistive load of 30 cm H2O for active group and chest physiotherapy plus EMT with a sham load for control group. Measures- Changes in maximal expiratory pressure (MEP) was considered as primary outcome, while maximal inspiratory pressures (MIP), dynamic and static lung volumes, oxygenation, perceived symptoms of dyspnoea, thoracic pain and well being (evaluated by visual analogic scale-VAS) and general health status were considered secondary outcomes. Results- All outcomes recorded showed significant improvements in both groups; however, the change of MEP (+34.2 mmHg, p<0.001 and +26.1%, p<0.001 for absolute and % of predicted, respectively) was significantly higher in Active group. Also VAS-dyspnoea improved faster and more significantly (p<0.05) at day 12 and 14 in Active group when compared with Control. The drop out rate was 6%, without differences between groups. Conclusions- In patients recovering from recent CTS specific EMT by Respilift™ is feasible and effective

Relapse risk factors in anti-N-methyl-D-aspartate receptor encephalitis

Aim: To identify factors that may predict and affect the risk of relapse in anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. Method: This was a retrospective study of an Italian cohort of patients with paediatric (≤18y) onset anti-NMDAR encephalitis. Results: Of the 62 children included (39 females; median age at onset 9y 10mo, range 1y 2mo–18y; onset between 2005 and 2018), 21 per cent relapsed (median two total events per relapsing patient, range 2–4). Time to first relapse was median 31.5&nbsp;months (range 7–89mo). Severity at first relapse was lower than onset (median modified Rankin Scale [mRS] 3, range 2–4, vs median mRS 5, range 3–5; admission to intensive care unit: 0/10 vs 3/10). At the survival analysis, the risk of relapsing was significantly lower in patients who received three or more different immune therapies at first disease event (hazard ratio 0.208, 95% confidence interval 0.046–0.941; p=0.042). Neurological outcome at follow-up did not differ significantly between patients with relapsing and monophasic disease (mRS 0–1 in 39/49 vs 12/13; p=0.431), although follow-up duration was significantly longer in relapsing (median 84mo, range 14–137mo) than in monophasic patients (median 32mo, range 4–108mo; p=0.002). Interpretation: Relapses may occur in about one-fifth of children with anti-NMDAR encephalitis, are generally milder than at onset, and may span over a long period, although they do not seem to be associated with severity in the acute phase or with outcome at follow-up. Aggressive immune therapy at onset may reduce risk of relapse. What this paper adds: Relapses of anti-N-methyl-D-aspartate receptor encephalitis may span over a long period. Relapses were not associated with severity in the acute phase or outcome at follow-up. Aggressive immune therapy at onset appears to decrease risk of relapse

Corrosione delle armature in calcestruzzo armato allo stadio G. Meazza di Milano - Il monitoraggio delle strutture del primo e del secondo anello

The structures of the three rings of the stadium "Giuseppe Meazza" in Milan, built in different stages from 1926 until 1990, is a remarkable evidence of the use of reinforced and prestressed concrete in the last century. If, on the one hand, these structures represent an icon for the potential of this material, on the other hand they also highlight its vulnerability. Reinforced concrete structures of the first and second rings are more than 60 years old and suffer from the effects of corrosion of the steel reinforcement. The municipality of Milan, being the owner of the stadium, has set up a collaboration with Politecnico di Milano aimed at the assessment of the conservation condition of the structures and planning of remedial works necessary to preserve and, at the same time, ensure the correct use of this important infrastructure. This paper describes the investigations carried out on the structures of the first and second ring (dating to 1926-37 and 1955 respectively), which allowed the definition of the extension of carbonation of concrete and the state of corrosion of the reinforcement. The opportunity to monitor the progress of the reinforcement corrosion was also highlighted in order to plan repair works. For this purpose, a monitoring system based on probes for measuring the corrosion potential of the reinforcement and electrical resistivity of concrete is under development

Un Prototipo Di Pianoforte Digitale Con Feedback Vibrotattile

Questo lavoro presenta i risultati di due esperimenti percettivi compiuti su un prototipo di pianoforte digitale aumentato. L'obiettivo di entrambi gli esperimenti era studiare la percezione da parte del pianista di feedback vibrotattile sulla tastiera. Nel primo esperimento i soggetti coinvolti dovevano suonare liberamente al variare del feedback, e fornire un giudizio sulla qualit\ue0 percepita dello strumento in una griglia di cinque attributi: controllo dinamico, ricchezza, coinvolgimento, naturalezza, e preferenza complessiva. Nel secondo esperimento si \ue8 misurata l'accuratezza (in termini di tempo e di controllo dinamico) nell'esecuzione di una scala, al variare del feedback. I risultati mostrano una preferenza per le condizioni in cui \ue8 presente feedback vibrotattile, tuttavia per quanto riguarda l'accuratezza dell'esecuzione non sono state osservate differenze significative tra le diverse condizioni