최승문 교수

This paper reviews the technology and applications of vibrotactile display, an effective information transfer modality for the emerging area of haptic media. Our emphasis is on summarizing foundational knowledge in this area and providing implementation guidelines for application designers who do not yet have a background in haptics. Specifically, we explain the relevant human vibrotactile perceptual capabilities, detail the main types of commercial vibrotactile actuators, and describe how to bu

New sophisticated haptic-rendering algorithms let users experience virtual objects through touch. We systematically investigate the unrealistic behavior of virtual haptic textures. The emerging science of haptic rendering consists of delivering properties of physical objects through the sense of touch. Owing to the recent development of sophisticated haptic-rendering algorithms, users can now experience virtual objects through touch in many exciting applications, including surgical simulations,

The force-constancy hypothesis states that the user of a force-feedback device maintains a constant penetration force when stroking virtual surfaces in order to perceive their topography. The hypothesis was developed to address a real-world data perceptualization problem where the perception of surface topography was distorted when the surface stiffness was nonuniform. Two experiments were conducted. In Experiment I, we recorded the penetration depths of the probe tip while the user stroked two

This paper presents a quantitative characterization of the instability that a human user often experiences while interacting with a virtual textured surface rendered with a force-reflecting haptic interface. First, we quantified the degree of stability/ instability during haptic texture rendering through psychophysical experiments. The stiffness of the virtual textured surface upon detection of instability was measured under a variety of experimental conditions using two texture rendering method

The use of distinguishable complex vibrations that have multiple spectral components can improve the transfer of information by vibrotactile interfaces. We investigated the qualitative characteristics of dual-frequency vibrations as the simplest complex vibrations compared to single-frequency vibrations. Two psychophysical experiments were conducted to elucidate the perceptual characteristics of these vibrations by measuring the perceptual distances among single-frequency and dual-frequency vibr

This paper investigates the problem of perceived instability during haptic texture rendering. We focus on the perceptual analysis of the stability of textured surfaces rendered with a force-reflecting device. The method of limits is used to assess the detection thresholds for perceived instability in terms of the stiffness of the virtual textured surfaces. We varied texture rendering method, exploration mode, and the amplitude and spatial wavelength of a sinusoidal surface texture model. Our res

This article proposes a general regime-switching univariate diffusion model to describe the dynamics of the short-term interest rate. The maximum likelihood estimates are obtained using the weekly series of U.S. three-month treasury bill rates. The estimation results reveal that there are strong evidences for the existence of high and low volatility regimes, for the time varying transition probability of the regime variable, and for the high persistence of both regimes. In both regimes, the vola

This paper presents a quantitative characterization of the instability that a human user often experiences while interacting with a virtual textured surface rendered with a force-reflecting haptic interface. Psychophysical experiments were conducted to measure the maximum stiffness under which virtual textured surfaces were perceived to be stable in a variety of conditions differing in texture model parameters, rendering method, and exploration mode. Unlike our previous study that used a collisi

This article reports the second study in a series that investigates perceived instability—unrealistic sensations associated with virtual objects—of virtual haptic texture. Our first study quantified the maximum stiffness values under which virtual haptic textures were perceived to be stable (Choi & Tan, 2004). The present study investigated the effect of the collision-detection algorithm by removing the step changes in force magnitude that could have contributed to perceived instability in t

This study investigates the effect of update rate on the quality of haptic virtual textures, with the goal to develop a guideline for choosing an optimal update rate for haptic texture rendering. Two metrics, control stability and perceived quality of the virtual haptic texture, were used. For control stability, we examined the effect of update rate on the “buzzing” of virtual haptic textures. For perceived quality, we measured the discriminability of virtual haptic textures rendered at differen

The emerging science of haptic rendering consists of delivering properties of physical objects through the sense of touch. Owing to the recent development of sophisticated haptic-rendering algorithms, users can now experience virtual objects through touch in many exciting applications, including surgical simulations, virtual prototyping, and data per-ceptualization. Haptics holds great promise to enrich the sensory attributes of virtual objects that these systems can produce.