Conference Paper

The Effect of Weight on the Perception of Vibrotactile Intensity with Handheld Devices.

DOI: 10.1109/WHC.2007.112 Conference: Second Joint EuroHaptics Conference and Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems (WHC 2007), 22-24 March 2007, Tsukuba, Japan
Source: DBLP

ABSTRACT The objective of this study was to determine whether the weight of a vibrating handheld object influenced the per- ceived intensity of its vibrations. Experiments were con- ducted to determine the subjective equivalence of vibrotac- tile intensity for objects that had the same size but had dif- ferent weights. The results suggest that for the same surface acceleration and hence the same movement, the heavier is the device, the stronger is the perceived intensity.

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    ABSTRACT: Vibrotactile signals are ubiquitous in everyday life, occurring both when manipulating objects and operating power tools. To bring haptics to ambient systems (defined as being embedded in everyday objects), the vibrotactile channel presents itself as a perceptually and energetically efficient method of conveying haptic information. Mobile phones are by far the most popular haptic-enabled devices. Yet, they are often equipped with common vibration motors of narrow-bandwidth capability. A voice-coil vibrotactile transducer design has been demonstrated to be high-bandwidth and capable of functioning under the same enclosure-vibration paradigm. The transducer was modeled by converting its mechanical free-body diagram into equivalent electrical circuits. The experimentally obtained transfer function was combined with the function established theoretically to obtain the impedance expression for each parameter. Using the aforementioned actuator, mock cellphones were made for vibrotactile perception experiments. Employing pulsed vibration signals to combat adaptation effects, experiments were performed to study the effect of weight and underlying vibration frequency on perceived strength. Results show that for the same measured acceleration on the device, a heavier box is perceived to vibrate with greater strength. Furthermore, signals with higher underlying frequency are perceived to be weaker for the same measured acceleration. The results obtained from ungrounded, vibrating objects are consistent with previous studies using grounded devices. The findings suggest the need for a systematic correction rule that assists cellphone designers in how to modify the device's vibratory characteristics according to its weight and the operating frequency. An ambient haptic device is implemented to synthesize haptic cues resulting from an object rolling down and impacting the inside wall of a tubular cavity. When an object rolls or slides, a variety of cues become available for the estimation of its location inside the cavity. These cues are related to the dynamics of an object subjected to the laws of physics such as gravity and friction. Perception experiments were conducted, in which participants attempted to discriminate among three virtual tubes of different lengths after making the virtual ball roll down. The results support the hypothesis that the subjects mastered the laws related to the dynamics of objects under the influence of gravity and used them to perceive the length of the invisible cavities. Les signaux vibrotactiles sont omniprésents dans la vie quotidienne. Ils se manifestent soit quand on manipule les objets soit lorsque l'on touche des machines. Afin de donner aux "systèmes ambiants" la possibilité de communiquer aux utilisateurs par l'haptique, les signaux vibrotactiles s'avèrent être un moyen efficace, tant au point de vue de leur perception que de la consommation énergétique. Les téléphones portables sont, de loin, les appareils ayant des capacités haptiques les plus communs. Ils sont munis de moteurs vibrants ayant une bande passante limitée. Nous avons réalisé un transducteur vibrotactile à large bande passante et qui permet de faire vibrer la boite entière, comme dans un téléphone portable. Ce transducteur a été modélisé du point de vue de l'électromécanique, puis transformé en circuits électriques équivalents pour en faciliter l'analyse. La fonction de transfert a été obtenue expérimentalement, par puis comparée à la fonction obtenue théoriquement afin d'obtenir l'impédance de chaque composant du transducteur. Ces transducteurs ont été utilisés dans la fabrication d'appareils pour l'étude de la perception. Une série d'expériences a été menée afin étudier l'effet du poids et de la fréquence de vibration sur la perception vibrotactile. Les résultats démontrent que pour une même accélération, on perçoit les vibrations comme étant plus fortes s'il s'agit d'un objet plus lourd. D'autre part, on les perçoit comme étant plus faibles si elles sont d'une fréquence plus élevée. Ces résultats correspondent à peu près à ceux trouvés avec des appareils fixés au sol. Par conséquent, il serait souhaitable d'avoir des règles de correction des caractéristiques des vibrations d'un appareil mobile en fonction de son poids et la fréquence de stimulation. Un dispositif de simulation haptique a également été construit pour simuler les sensations haptiques résultantent d'un objet qui roule ou glisse au long d'une cavité tubulaire et qui heurte des paroies internes. Lorsqu'un objet roule ou glisse, plusieurs types d'indices haptiques sont disponibles et informent sur la position de l'objet. Ces indices sont liés à la dynamique de l'objet soumis aux lois du mouvement qui résulte de la gravité et de la friction. Une expérience de perception a été effectuée, où les participants faisaient rouler la balle virtuelle et tentaient d'estimer la distance parcourue. Les résultats supportent l'hypothèse que l'on maîtrise les invariants liés à la dynamique d'un objet se déplaceant sous l'influence de la gravité, et qu'on est capable de les utiliser pour percevoir la taille de cavités invisibles.
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    ABSTRACT: Weight perception has been of great interest for over three centuries. Most research has been concerned with the weight of static objects, and some illusions have been discovered. Here, we show a new illusion related to the perception of the heaviness of oscillating objects. We performed experiments that involved comparing the weight of two objects of identical physical appearance but with different gross weights and oscillation patterns (vibrating vertically at frequencies of 5 or 9 cycles per second with symmetric and asymmetric acceleration patterns). The results show that the perceived weight of an object vibrating with asymmetric acceleration increases compared to that with symmetric acceleration when the acceleration peaks in the gravity direction. In contrast, almost no heaviness perception change was observed in the anti-gravity direction. We speculate that the reason for the divergence between these results is caused by the differential impact of these two hypothesized perceptual mechanisms as follows: the salience of pulse stimuli appears to have a strong influence in the gravity direction, whereas filling-in could explain our observations in the anti-gravity direction. The study of this haptic illusion can provide valuable insights into not only human perceptual mechanisms but into the design of ungrounded haptic interfaces.
    IEEE Transactions on Haptics 02/2008; 1(1):9-18. · 1.39 Impact Factor
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    ABSTRACT: This paper addresses the question of strength perception for vibration signals used in mobile devices. Employing devices similar to standard cell phones and using pulsed vibration signals to combat adaptation effects, experiments were performed to study the effect of weight and underlying on perceived strength. Results shows that for the same measured acceleration on the device, a heavier box is perceived to vibrate with greater strength. Furthermore, signals with higher underlying frequency are perceived to be weaker for the same measured acceleration. While our results are consistent with previous studies, they are obtained for the specific condition of ungrounded, vibrating objects held in the hand. Our results suggest the need for a systematic correction law for use by designers to specify the vibratory characteristics of a device as a function of its weight and of the desired operating frequency.
    IEEE Transactions on Haptics 04/2010; · 1.39 Impact Factor

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