Jongman Seo

Initial study for creating linearly moving vibrotactile sensation on mobile device

This paper investigates the feasibility of creating spatially moving vibrotactile sensations using two vibrotactile actuators in a mobile device. The idea is based on well-known tactile illusions of apparent tactile motion and “phantom” sensation. The phantom sensation refers to a perceptual phenomenon where spatially separated vibrotactile actuators that stimulate different skin zones induce a single tactile sensation midway between the two stimulation points. We tested whether such sensation can also be elicited in a mobile device via a psychophysical experiment that employed an open response paradigm. Experimental conditions differed in vibration rendering method, signal duration, and sensation movement direction. The subjects answered the perceived positions and intensities of vibrotactile sensations by drawing graphs with respect to time. The results demonstrated that such “vibrotactile flow” can be reliably produced in a mobile device and that a performance trade-off exists depending on the method and signal duration used for rendering. The findings of this paper can be applied to the user interface design of a mobile device with enriched vibrotactile sensations and an improved information transfer bandwidth.

TAXEL: Initial progress toward self-morphing visio-haptic interface

This paper proposes a new interactive interface TAXEL, which aims at developing a reconfigurable self-morphing visio-haptic interface. We first present the overall architecture and concept of a self-morphing visuo-haptic interface. Key hardware components are developed and tested, including three tactile actuators using a piezoelectric active linear actuator, a passive MR fluid actuator, and a thin film-type actuator, respectively, and a flexible visual display based on the light-waveguide technology. Using the developed components, a tactile platform that includes a 8×16 array of the linear actuators is implemented for a proof of concept. A rendering engine is also designed for the tactile platform with emphasis on the use of haptic feedback together with GUI. We also carried out a user study with virtual button simulation as a benchmark to evaluate the performance of the TAXEL tactile platform. Lastly, an integrated system with a visual display is demonstrated along with several application examples.

Substituting Motion Effects with Vibrotactile Effects for 4D Experiences

In this paper, we present two methods to substitute motion effects using vibrotactile effects in order to improve the 4D experiences of viewers. This work was motivated by the needs of more affordable 4D systems for individual users. Our sensory substitution algorithms convert motion commands to vibrotactile commands to a grid display that uses multiple actuators. While one method is based on the fundamental principle of vestibular feedback, the other method makes use of intuitive visually-based mapping from motion to vibrotactile stimulation. We carried out a user study and could confirm the effectiveness of our substitution methods in improving 4D experiences. To our knowledge, this is the first study that investigated the feasibility of replacing motion effects using much simpler and less expensive vibrotactile effects.

Edge flows: Improving information transmission in mobile devices using two-dimensional vibrotactile flows

Vibrotactile flows refer to vibrotactile sensations that move continuously on the surface of a mobile device. They have been studied to render one-dimensional illusory movements using two actuators. In this work, we extend the dimension of vibrotactile flows to two dimensions by means of edge flows-vibrotactile flows that rotate along the edges of a rectangular mobile device, rendered using four actuators placed at its four corners. We designed 32 edge flows and carried out a longitudinal user study in order to measure the information transmission capacity of edge flows, while looking into the effects of practice and correct-answer feedback on the identification accuracy of edge flows. Results showed that the information transmission capacity of the edge flows was 3.70 bits, which is greater than for most previous studies; that some extent of practice is required for robust identification, but it can take place quickly; and that correct-answer feedback is advantageous but its degree of improvement was less than that of repeated practice. Our findings can contribute to enlarging the design space of tactile stimuli for robust transmission of abstract information to mobile device users.

4D Experiences Enabled by Automatic Synthesis of Motion and Vibrotactile Effects

4D experiences are one of the most immersive kinds of experiences that current virtual reality technologies can offered. However, the production of 4D contents is still very labor-intensive, and it has been a major obstacle against the wider spread of 4D platforms. In this demonstration, we present two methods that generate motion and vibrotactile effects automatically from the audiovisual content of a movie. Our synthesis methods provide compelling 4D experiences to viewers while greatly improving the productivity.