Hojin Lee

Mid-air tactile stimulation using laser-induced thermoelastic effects: The first study for indirect radiation

This paper reports our recent finding that a laser that is radiated on a thin light-absorbing elastic medium attached on the skin can elicit a tactile sensation of mechanical tap. Laser radiation to the elastic medium creates inner elastic waves on the basis of thermoelastic effects, which subsequently move the medium and stimulate the skin. We characterize the associated stimulus by measuring its physical properties. In addition, the perceptual identity of the stimulus is confirmed by comparing it to mechanical and electrical stimuli by means of perceptual spaces. All evidence claims that indirect laser radiation conveys a sensation of short mechanical tap with little individual difference. To the best of our knowledge, this is the first study that discovers the possibility of using indirect laser radiation for mid-air tactile rendering.

Haptic simulation of refrigerator door

Recently, haptics has begun to impact consumer products, e.g., mobile phones and automobiles. In this paper, we introduce one such new application, that is, haptic simulation of refrigerator operation, and present an initial prototype for the front door. A one degree-of-freedom haptic interface is designed and built to provide torque feedback of the front door. Simulation software consisting of system control, graphic renderer, and haptic renderer are also developed. For haptic rendering, the motion dynamics of a refrigerator door is modeled, and the haptic renderer is implemented based on the dynamics model. Lastly, we report a user experiment carried out to assess the perceived similarity between simulated and real door operations, i.e., the realism, which shows promising results.

Haptic Assistance for Memorization of 2-D Selection Sequences

This paper investigates the effect of haptic feedback on the learning of a 2-D sequential selection task, used as an abstraction of complex industrial manual assembly tasks. This mnemonic-motor task requires memorization of the selection order of points scattered on a 2-D plane and reproduction of this order using entire arm movements. Four information presentation methods, visual information only, visual information + enactment, visual information + haptic guidance, and visual information + haptic disturbance, are considered. The latter three methods provide different levels of haptic kinesthetic feedback to the trainee. We carried out a user study to assess the quantitative performance differences of the four training methods using a custom-built visuo-haptic training system. Experimental results showed the relative advantages and disadvantages of each information presentation method for both short-term and long-term memorization. In particular, training with only visual information was the best option for short-term memory, while training also with haptic disturbance was the most effective for long-term memory. Our findings have implications to designing a training method that is suitable for given training requirements.

LaserStroke: Mid-air Tactile Experiences on Contours Using Indirect Laser Radiation

This demonstration presents a novel form of mid-air tactile display, LaserStroke, that makes use of a laser irradiated on the elastic medium attached to the skin. LaserStroke extends a laser device with an orientation control platform and a magnetic tracker so that it can elicit tapping and stroking sensations to a users palm from a distance. LaserStroke offers unique tactile experiences while a user freely moves his/her hand in midair.

Mid-Air Tactile Stimulation Using Indirect Laser Radiation

In this paper, we demonstrate that a laser irradiated on a thin light-absorbing elastic medium attached on the skin can elicit a tactile sensation of mechanical tap. First, we present simulation results that show laser irradiation to the elastic medium creates inner elastic waves on the basis of thermoelastic effects and these elastic waves trigger the bending deformation of the medium, which then stimulates the skin. Second, we analyze the physical properties of the associated stimulus by measuring its force profile. Third, we identify the perceptual characteristics of the stimulus in comparison to those of mechanical and electrical stimuli by means of a perceptual experiment employing dissimilarity rating. All the evidence indicates that indirect laser radiation provides a sensation of short mechanical tap. Furthermore, little individual difference was observed in the results of the perceptual experiment. To the best of our knowledge, this study is the first in reporting the feasibility of indirect laser radiation for mid-air tactile rendering.

Mid-air tactile display using indirect laser radiation for contour-following stimulation and assessment of its spatial acuity

This paper presents a mid-air tactile display based on indirect laser radiation designed to provide continuous moving tactile sensations along a contour on the skin. The display uses a small laser device with 1064 nm wavelength mounted on a motorized gimbal for the control of laser radiation direction. A laser is irradiated on an elastic medium attached to the users body, and the medium is made of black rubber-coated polyvinyl chloride (PVC) for laser-induced thermoelastic deformation. LaserStroke generates tactile stimuli sufficient for clear perception, and this is confirmed by measurements. We also report a psychophysical experiment carried out to study the spatial acuity of laser-induced tactile stimuli by measuring point localization thresholds. Results indicate that LaserStroke has adequate performance for transmitting continuously moving tactile sensations through the air.

Haptic-Enabled English Education System

For computer-based education, virtual environments equipped with haptic devices have been used to aid the learning process. The main benefit of haptics technology is that it can improve the realism of virtual environments. This paper describes a haptic-enabled English education system for elementary students. We demonstrate two game-based scenarios which allow users to learn English and scientific laws by exploring in virtual environments with a haptic interface.

POMY: POSTECH Immersive English Study with Haptic Feedback

In this paper, we propose a novel CALL (Computer-Assisted Language Learning) system, which is called POMY (POSTECH Immersive English Study). In our system, students can study English while talking to characters in a computer-generated virtual environment. POMY also supports haptic feedback, so students can study English in a more interesting manner. Haptic feedback is provided by two platforms, a haptic chair and a force-feedback device. The haptic chair, which is equipped with an array of vibrotactile actuators, delivers directional information to the student. The force-feedback device enables the student to feel the physical properties of an object. These haptic systems help the student better understand English conversations and focus on studying. We conducted a user experiment and its results showed that our haptic-enabled English study contributes to better learning of English.

Haptic-enabled driving training system

The objective of the current work is a driving training system to capture and transfer skills from the expert to the novice drivers. The emphasis is on the haptic feedback applied on the steering wheel and the accelerator pedal to improve trainees performance. For capturing skills, driving signals of an expert driver, performing a given task using a developed driving simulator, are recorded as reference trajectories. For transferring, two different methods are considered: guidance to assist and disturbance to distract following the reference. For evaluation, two performance measures are assumed: trajectory-based and model-based. They are used not only to evaluate the progress of the trainee but also to tune the gain of controllers delivering haptic feedback.

Effect of Active and Passive Haptic Sensory Information on Memory for 2D Sequential Selection Task

This paper introduces an education system for typical assembly procedures that provides various haptic sensory information including active and passive haptic feedbacks. Using the system, we implemented four kinds of training methods and experimentally evaluated their performances in terms of short-term and long-term memory over the task. In results, active haptic guidance showed beneficial effects on the short-term memory. In contrast, passive guidance showed the worst performance and even degraded the efficiency of short-term memory. No training methods resulted in noticeable improvements for the long-term memory performance.