Gunhyuk Park

Vibrotactile Feedback for Information Delivery in the Vehicle

As technology advances, more functions have been, and continue to be added to the vehicle, resulting in increased needs for improved user interfaces. In this paper, we investigate the feasibility of using vibrotactile feedback for in-vehicle information delivery. First, we measured the spectral characteristics of ambient vibrations in a vehicle, and designed clearly distinguishable sinusoidal vibrations. We further selected via dissimilarity rating the four sets of sinusoidal vibrations which had three to six vibrations. Second, we evaluated the learnability of the vibration sets when associated with common menu items of a Driver Information System (DIS). We also replaced the two most confused sinusoidal vibrations with patterned messages, and assessed the degree of learnability improvement. Finally, we evaluated the extent to which participants could select a desired function in a DIS via vibrotactile messages while simultaneously performing a driving-like primary task with higher priority. The results demonstrated high potential for vibrotactile messages to be effectively used for the communicative transfer of in-vehicle system information.

Perceptual space of amplitude-modulated vibrotactile stimuli

Amplitude-modulated vibrotactile stimuli have been broadly used for tactile perception and rendering research. However, understandings of the perceptual relations between amplitude-modulated vibrations are not comprehensive yet. In this paper, we present a perceptual analysis on the identifying characteristics of amplitude-modulated vibrations and their perceptual relations. We estimated the perceptual dissimilarities among one carrier and seven amplitude-modulated sinusoidal vibrations (150-Hz carrier frequency; seven modulation frequencies in 1–80 Hz) in a psychophysical experiment. The dissimilarity scores were inspected using multi-dimensional scaling to obtain an appropriate perceptual space. The optimal perceptual space was two-dimensional, where the vibration points exhibited a circular formation. The analysis showed that the pulse-like low-frequency sensation of an amplitude-modulated vibration increased for very low modulation frequencies (1–10 Hz), then decreased for higher modulation frequencies (10–80 Hz), and eventually converged to the smooth vibrational sensation of the 150-Hz carrier signal. It also suggested that the envelope waveform is primary information for the discrimination of amplitude-modulated signals, instead of their spectral energy distributions. These findings can contribute to the design of perceptually salient and distinctive vibrotactile signals using amplitude modulation.

Gesture-recognizing hand-held interface with vibrotactile feedback for 3D interaction

This article presents a hand-held interface system for 3D interaction with digital media contents. The system is featured with 1) tracking of the full 6 degrees-of-freedom position and orientation of a hand-held controller, 2) robust gesture recognition using continuous hidden Markov models based on the acceleration and position measurements, and 3) dual-mode vibrotactile feedback using both vibration motor and voice-coil actuator. We also demonstrate the advantages of the system through a usability experiment.

Tactile effect design and evaluation for virtual buttons on a mobile device touchscreen

In this paper, we present the design of a large number (72) of tactile stimuli for the confirmation feedback of virtual button presses on the mobile device touchscreen. Two industry standard variable-reluctance actuators (enhanced voice-coil actuators with added mass for stronger output) were used in the study. The design parameters of an input were amplitude, duration, carrier signal, envelope function, and actuator. Eighteen participants evaluated the modeled patterns with the criteria of similarity to physical buttons and user preference. An adjective rating task was also accompanied to assess the subjective quality of the designed tactile effects. Experimental results unveiled several important guidelines for designing realistic and favorable button-click tactile feedback. The findings of this paper have implications for improving the usability of user interface components displayed on a touchscreen by means of haptic feedback.

Attachable and detachable vibrotactile feedback modules and their information capacity for spatiotemporal patterns

This paper showcases attachable/detachable haptic modules, nicknamed haptic enchanters, by presenting their conceptual prototypes and quantifying their information transmission capacity. Haptic enchanters can be attached to ordinary devices and wearables to endow them with the ability of creating programmable haptic stimuli, thereby transforming them to effective haptic communication devices. In particular, our prototype enchanters are designed to localize vibrotactile stimulation to the neighborhood of attachment site, and this spatial isolation allows for effective spatiotemporal information delivery using multiple enchanters. We demonstrate that haptic enchanters enable very high capacity of information transfer (4.55–7.06 bits) for spatiotemporal vibration sequences rendered with 2, 3, and 4 enchanters. These results instantiate the performance of haptic enchanters as effective and convenient communication accessories and their potential for applications.

Tactile Information Transmission by 2D Stationary Phantom Sensations

A phantom sensation refers to an illusory tactile sensation perceived midway between multiple distant stimulations on the skin. Phantom sensations have been used intensively in tactile interfaces owing to their simplicity and effectiveness. Despite that, the perceptual performance of phantom sensations is not completely understood, especially for 2D cases. This work is concerned with 2D stationary phantom sensations and their fundamental value as a means for information display. In User Study 1, we quantified the information transmission capacity using an absolute identification task of 2D phantom sensations. In User Study 2, we probed the distributions of the actual perceived positions of 2D phantom sensations. The investigations included both types of phantom sensations-within and out of the body. Our results provide general guidelines as to leveraging 2D phantom sensations in the design of spatial tactile display.

A Physics-Based Vibrotactile Feedback Library for Collision Events

We present PhysVib: a software solution on the mobile platform extending an open-source physics engine in a multi-rate rendering architecture for automatic vibrotactile feedback upon collision events. PhysVib runs concurrently with a physics engine at a low update rate and generates vibrotactile feedback commands at a high update rate based on the simulation results of the physics engine using an exponentially-decaying sinusoidal model. We demonstrate through a user study that this vibration model is more appropriate to our purpose in terms of perceptual quality than more complex models based on sound synthesis. We also evaluated the perceptual performance of PhysVib by comparing eight vibrotactile rendering methods. Experimental results suggested that PhysVib enables more realistic vibrotactile feedback than the other methods as to perceived similarity to the visual events. PhysVib is an effective solution for providing physically plausible vibrotactile responses while reducing application development time to great extent.

PhysVib: Physically Plausible Vibrotactile Feedback Library to Collisions on a Mobile Device

This demo presents a mobile application using PhysVib: a software solution on the mobile platform extending an open-source physics engine for automatic vibrotactile feedback upon collision events in a multi-rate rendering architecture. PhysVib runs concurrently with a physics engine at a low update rate and generates vibrotactile feedback commands at a high update rate based on the simulation results of the physics engine using an exponentially-decaying sinusoidal model. We demonstrate an application showing three wall-object pairs with different material properties, and a user interacts with internal objects to feel vibrotactile feedback from collision events.