Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems 参加報告

This article describes the design of a high-bandwidth, iron-less, recoil-based electromagnetic vibrotactile actuator. Its working principle, the theoretical analysis, the method used to determine its transfer function, its scaling properties and its design constraints are discussed along with its fabrication and possible improvements.

Design and analysis of a recoil-type vibrotactile transducer.

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.

Asymmetric Oscillation Distorts the Perceived Heaviness of Handheld Objects

Vibrotactile rendering is one of the most popular means for improving the user interface of a mobile device, but the availability of related perceptual data that can aid vibrotactile effect design is not currently sufficient. The present paper reports data from a series of psychophysical studies designed to fill this gap. In Experiment I, we measured the absolute detection thresholds of sinusoidal vibrotactile stimuli transmitted to the hand through a mobile phone. Stimuli were generated by a mechanical shaker system that can produce vibrations over a broad frequency and amplitude range. The detection thresholds reported here are a new addition to the literature, and can serve as a baseline for vibrotactile stimulus design. In Experiment II, we estimated the perceived intensities of mobile device vibrations for various frequencies and amplitudes using the same shaker system. We also determined a form of parametric nonlinear function based on Stevens' power law and fit the function to the measured data. This psychophysical magnitude function, which maps vibration frequency and amplitude to a resulting perceived intensity, can be used to predict the perceived intensity of a mobile device vibration from its physical parameter values. In Experiment III, we measured another set of perceived intensities using two commercial miniature vibration actuators (vibration motor and voice-coil actuator) in place of the mechanical shaker. The purpose of this experiment was to evaluate the utility of the psychophysical magnitude function obtained in Experiment II, as vibrotactile stimuli produced by miniature actuators may have different physical characteristics, such as vibration direction and ground condition. Comparison of the results of Experiments II and III confirmed that the psychophysical magnitude function can reliably predict changing trends in the perceived intensity of mobile device vibration. We also discuss further research issues encountered during the investigation. The results presented in this paper may be instrumental in the design of effective vibrotactile actuators and perceptually-salient rendering algorithms for mobile devices.

Psychophysical model for vibrotactile rendering in mobile devices

We conducted an experiment to understand how mobile phone users perceive the urgency of ten simple vibration alerts that were created from four basic signals: short on, short off, long on, and long off. The short and long signals correspond to 200 ms and 600 ms, respectively. To convey the level of urgency of notifications and help users prioritize them, the design of mobile phone vibration alerts should consider that the gap length preceding or succeeding a signal, the number of gaps in the vibration pattern, and the vibration's duration affect an alert's perceived level of urgency. Our study specifically shows that shorter gap lengths between vibrations (200 ms vs. 600 ms), a vibration pattern with one gap instead of two, and shorter vibration all contribute to making the user perceive the alert as more urgent.

Designing an effective vibration-based notification interface for mobile phones

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.

Perceived Vibration Strength in Mobile Devices: The Effect of Weight and Frequency

The objective of this study was to determine whether the weight of a vibrating handheld object influenced the perceived intensity of its vibrations. Experiments were conducted to determine the subjective equivalence of vibrotactile intensity for objects that had the same size but had different 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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M. Cruz

Papers

Perceived Vibration Strength in Mobile Devices: The Effect of Weight and Frequency

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