Past Research

  • While technology advances improve the quality of touchscreen devices such as mobile phones and tablets, but their functionality is still limited to simple user interactions. At best, they can generate some simple monotonic vibrations in response to user actions. A natural interaction with such touchscreen devices requires better and more intuitive haptic feedback, tailored based on the application. Various friction displays enable a new tactile feedback on touchscreens, and electrovibration display is one of them.

  • We have studied about a data-driven thermal rendering framework for highly realistic re-creation of the thermal dynamics of real objects in a virtual environment. We begin with a physics-based model for thermal rendering and then extend it to compute the desired temperature of a thermal display without identification of the thermal parameters of real objects.

  • Virtual Reality(VR) is a computer-generated senario that reproduces a realistic experience and makes user feel being there. Many research about haptic interface and user experiments for improving immersion and presence are conducted nowadays. We've studied various topics in VR, from a rendering method for improving immersiveness to VR applicaitons. 

  • Haptic texture generally refers to a sensation caused by the fine structural irregularities of an object when we touch it. Since texture provides fundamental haptic information about the identity of the object, accurate modeling and rendering of surface texture are essential in many applications. Despite its importance, it still remains very challenging to model and render haptic texture in a realistic manner because haptic texture perception consists of multiple perceptual dimensions such as roughness-smoothness, warmness-coldness, hardness-softness, and stickiness-slipperiness.

  • Application of haptics in automobiles is a promising topic. We are working on assistive systems for drivers such as lane departure warning system (LDWS), as well as tactile applications of entertainment systems in automobiles. We evaluated the effectiveness of various non-intrusive torque patterns generated by a steering wheel as warning signal, as well as delivering directional informations to the drivers. As an in-car entertainment system, we are working on improved haptic rendering algorithm for vibrotactile seats.

  • Photos are a powerful medium for recording the moments of information and sharing them with others, but visuallyimpaired users have quite limited access to photos’ benefits. This project presents TouchPhoto, which provides visualaudio-tactile assistive features to allow visually-impaired users to take and understand photos independently. A user can take photos with auditory guidance and record several audio tags to aid recall of the photo’ content. For comprehension, a user can listen to the audio tags embedded in a photo and also touch the photo using an electrostatic friction display.

  • Viscoelastic response modeling is one of the key parts of realistic haptic modeling in so-called high definition haptic technology. Viscoelasticity means non-linear responses resulted from the moving surface point in the surface of the deformable objects. We studied data-driven modeling and rendering of viscoelastic responses deformable objects. We modeled those responses using Radial Basis Function with the recorded responses of various deforming routes considering the friction responses.

  • Rendering a stiff virtual surface using a force-feedback haptic interface has been one of the most classic and important research issues in haptics. In this research, we present a novel haptic rendering technique, named stiffness shifting, which greatly increases the perceived hardness of a virtual surface. The key idea of stiffness shifting is to use a stiffness profile that includes an instantaneous increment shortly after a contact. The algorithm is very simple, and can be easily integrated into existing haptic rendering algorithms for 3D objects.

  • Recent motor learning researches aim at establishing methodology for modeling human sensorimotor skills and transferring the modeled skills to the trainee using haptic interfaces.  Standing on a research continuum, we developed a unique haptic VR driving training simulator providing error-corrective haptic feedback for learning a driving skill, which is a routine sensorimotor task but still difficult for novice drivers to learn without any frustration.

  • There are growing interests on emotional interaction in both of academia and industry. To design an effective interaction via haptic sensation, investigation on affective characteristics of them is needed. Therefore, we have been investigated emotional responses of various types of tactile stimulus, includes vibrotactile and thermal stimuli.

  • There are growing interests on emotional interaction in both of academia and industry. To design an effective interaction via haptic sensation, investigation on affective characteristics of them is needed. Therefore, we have been investigated emotional responses of various types of tactile stimulus, includes vibrotactile and thermal stimuli.

  • Creating haptic effects that are well synchronized with visual-audio content is not a trivial task, requiring good software tools and significant man hours. One promising approach to alleviate this problem is to provide algorithms that can automatically synthesize haptic effects by extracting important features from existing visual-audio content.

  • Musical experiences and haptic (tactile) experiences shares many characteristics, such as rhythm, pitch, and dynamics (change of amplitudes). Our research of haptic music focused on: 1) haptic rendering of music and 2) haptic interfaces for musical instrument learning. To render music haptically, we extracted musical features such as rhythms, beats, and salient melody and convert it to haptic stimulus to rich expressions to users. We also suggested and evaluated the effectiveness of a haptic guidance method for string instrument learning.

  •  This research is about 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 have pursued diverse research projects in order to improve and extend user interaction and experience by means of vibrotactile feedback on several different platforms including mobile devices, automobiles, and chairs. To this end, understanding human perception of complex vibrotactile stimuli is essential to develop effective interfaces. Our research outcomes may provide applied yet crucial knowledge on vibrotactile perception for many important applications.

  • Mobile devices are an indispensable personal gadget in our daily life. It, however, suffers from relatively inconvenient user interface because of its small form factor. As such, extending the limited UI of mobile devices using vibrotactile feedback has been an intensive research topic in both academics and industry. We have been conducting various research topics in this regard. Many of our projects were supported by or in collaboration with major companies including LG Electronics and Samsung Electronics.

  • Haptic augmented reality (AR) allows a user to explore a real environment augmented with virtual haptic stimuli. For example, medical students can palpate a virtual tumor inside a real mannequin using a haptic AR system to practice cancer screening. To realize such functionality of haptic AR, we need to alter the haptic attributes of a real object by means of virtual haptic feedback. Our research for haptic AR aims at developing a systematic methodology for modulating the haptic properties of a real object with the aid of a haptic interface.

  • This project aims at establishing methodology for modeling human sensorimotor skills and transferring the modeled skills to the trainee using haptic interfaces. Just like visual images and sound files, human skills should be able to be stored in digital media and reproduced on the need basis. This research strives to find effective means for coherent skill modeling and transfer, covering both force-feedback and vibrotactile interfaces.This project is supported by National Research Foundation of Korea under the National Research Laboratory (NRL) Program (currently called Do-Yak).

  • Convenient software that facilitates production of haptic content is indispensable for the widespread of haptics technology to the general public. However, such tools are very rare, and research effort to develop good ones has been less intense. To respond to this need, we have been developing several authoring tools for vibrotactile stimuli with distinctive features.

  • Force-feedback interface can provide force to the user, inducing net movements of the user's body. We've studied about force-feedback haptic interface for modeling tasks. Our representative work is haptic pottery modeling using circular sector element method.

  • A mobile haptic interface (MHI) is a force-feedback haptic interface with a mobile base. It allows to render very large virtual objects in a safe and portable manner.

  • Virtual prototyping can reduce a great amount of money in designing a product since we can easily predict the appearance of the final outcome. One limitation of traditional virtual prototyping technologies is that they can't provide the expected haptic experience. Inspired by this problem, we develope a haptic virtual prototyping system for a refrigerator door. A user can perceive the opening sensation of the designed door via our custom 1 DoF haptic device, while the 3D visual scene of the door is rendered by a visual display.

  • We investigated the feasibility of using vibrotactile feedback for in-vehicle information delivery and collision warning.

  • The surface topography information with varying stiffness rendered with the conventional penalty-based method can be distorted. Therefore, we developed a topography compensation algorithm based on the theory of force constancy in order to resolve the problem.

  • We studied about motion-based interaction and applications.

  • We studied a surgical robot with torque feedback for spinal fusion.

  • We also studied topics in computer graphics, especially for tracking of visually attended object and depth-of-field rendering.