Byung-Kil Han

Small and lightweight tactile display(SaLT) and its application

This paper presents a small and lightweight tactile display system and describes its capabilities with respect to spatial and temporal tactile feedback. Each tactile display module is comprised of a 4×4 piezoelectric ultrasonic actuator array with a spatial resolution of 1.5mm and a temporal resolution of 20Hz. The objective of this research is to build a small and lightweight tactile display system such that the system, including the display modules and complete controller parts, will be wearable by a user. It was found that the developed tactile display module can display both spatial and temporal information with less power consumption.

Continuous Position Control of 1 DOF Manipulator Using EMG Signals

One of the main problems of robot manipulations by using bio-signal interface is discontinuous position control. This discontinuity causes undesirable effects on users such as lack of accuracy and an overall degraded performance. This paper presents the control strategy for the continuous position control of 1 DOF manipulator using electromyography (EMG) signals. We designed the control system which makes possible that 1 DOF manipulator replicate the wrist movements by estimating the wrist joint angle continuously from EMG signals measured from the four muscles. In order to estimate the joint angle, we transformed raw EMG signals to quasi-tensions, which represent the actual muscle tension, using low-pass filtering. A supervised multi-layer neural network trained by a back-propagation algorithm which estimates a joint angle from quasi-tensions, so that the proposed system controls the manipulator continuously with the obtained time-varying angle. The proposed methodology can be applied to improve the control strategy for tele-operated robotic manipulator.

Physical mobile interaction with kinesthetic feedback

As the gestural interface is emerging as one of the key interfaces for mobile computing, the ability of these interfaces to provide physical feedback is becoming more important. Especially in the context of interacting with a virtual world, generating proper feedback is more important when seeking to engage users in a simulated world. However, due to the inherent size problems of mechanical structures and due to power issues, most handheld devices relied on vibrotactile feedback. To resolve this issue, this paper proposes a haptic interface module that can represent realistic kinesthetic feedback for use with hand interfaces. Large-scale but slowly changing force is generated using a linear servomotor to provide general object information, such as the overall shape of an object. On the other hand, subtle haptic feedback generated by a solenoid-magnet pair provides the detailed surface properties of the object. To measure the performance of the proposed system, two experiments are conducted. From the experimental results, it was revealed that the proposed solenoid-magnet pair could generate about 1N of magnetic force. In terms of perception, the device can provide six levels of kinesthetic feedback. As an application, we propose depth-based interaction in which the proposed system is controlled by a depth-measuring unit.

Development of an impact-resonant actuator for mobile devices

This paper presents a novel impact-resonant actuator (IRA) that can increase a degree of reality and a sense of immersion by providing a delicate haptic sensation. In current mobile devices, eccentric rotary motor and linear resonant actuators are widely used for haptic feedback, but they provide only simple vibration response to a users on-screen touch. Varied vibration patterns cannot be generated due to their limited working frequency range. Also, it is hard to create crisp vibrotactile sensation which can mimic the sensation of pressing a button due to their slow response time and long residual vibration. To overcome the limitations of conventional actuators, the proposed actuator generates impact vibration, operating at a wide frequency range from 0 Hz to 190 Hz with a fast response time and very short residual vibration. Moreover, stronger impact force can be generated effectively near the resonant frequency.

Interaction with a display panel - An evaluation of surface-transmitted haptic feedback

This paper addresses the role of tactile feedback in touch-based interaction. The focus was on touch interaction on a surface as a natural interaction method and on surface-transmitted tactile feedback. The paper is an extension of previous research involving pin-array based tactile displays. For tactile impulses or vibrations, both a piezoactuator and a solenoid were utilized. A user can perceive discernable tactile impulses through the proposed actuators in a manner that differs from existing vibration motors. Psychophysical results also reveal that low-frequency vibrations or impulses can be used to create roughness on a smooth and nearly frictionless touch surface. A LDV (Laser Doppler Vibrometer), Ometron VH300, was utilized to measure the frequency responses of the surface vibrations and impulses. The rise time of the proposed system was less than 1 ms.

Haptic interaction with virtual geometry on robotic touch surface

Touch screens are rapidly penetrating our daily life. Even general users are enjoying various applications such as drawing sketches and playing games with their mobile phones. In particular, the improvement of graphics capabilities with large display screens now allows easy access at any location to 3D environments including 3D games, animation, and augmented reality applications that were formerly limited to desktop environments. Touch screen devices have distinct features compared with previous mobile phones: the screen is widened and the device is mainly operated with touch input. As a natural consequence, users want to be able to feel the touched objects in many cases. From the viewpoint of haptics on surfaces, a variety of haptic rendering/interaction techniques have been proposed to make interactions on surface richer and more natural. One approach to lend applications tactility is to provide frictional feedback on touch surfaces [Bau and Poupyrev 2012; Kim et al. 2013; Winfield et al. 2007]. These technologies plausibly reproduce finetuned textures, such as craters on the surface of the Moon and the lines on the palm of a hand. However, the technologies are not suitable to reproduce the object surface with contours that extend beyond the fingertip, such as the large-scaled geometry of the Moon and the palm. To handle such issues, a recent work proposed a lateral haptic display that can provide two-dimensional force feedback slightly above the screen [Saga and Deguchi 2012]. They exploited the phenomenon that people tend to have the perception of touching 3D objects if they receive force feedback in/against the direction of movement on a 2D surface. A similar technique was applied to image-based haptic interaction in another recent work [Kim and Kwon 2013]. This type of feeling can be reproduced by considering one important feature of haptics: collocation, which is often ignored in the context of surface interaction in that interaction space is limited to a 2D surface. This is a substantially different setup from that used for conventional haptic rendering, which generally collocates haptic information in the real interaction space. A recent study dealt with this issue by proposing a 1-dimensional translational robot system [Sinclair et al. 2013]. Their robotic touch display allows users to explore virtual 3D content such as volumetric medical images by moving the display surface along the z-axis perpendicular to the display surface. This trial has significant meaning as the first work to take collocation into consideration in the context of surface haptics. Another recent study addressed this issue by proposing a haptic stylus with a variable tip length. The proposed system is designed to give users the illusion that some part of the stylus is immersed in virtual space, enabling the direct touch of virtual objects displayed on the flat surface [Withana et al. 2010].

Interaction with objects inside a media space

In this paper, we describe media that can provide a physics engine with predefined object information. Once the object descriptors are embedded into an image as metadata via a technique that hides the information, the information can be decoded for the construction of a rigid body object during rendering. In this manner, a user can interact with and obtain sensory feedback from the object in a world constructed from a single proposed image.

Simultaneous Representation of Texture and Geometry on a Flat Touch Surface

We propose to combine two types of tactile feedback, electrovibration and mechanical vibration, for haptic interaction on a flat touch surface. This approach would enrich haptic effects for touch screen-based devices by simultaneously providing texture and geometry information.

Haptic Snake: Line-Based Physical Mobile Interaction in 3D Space

This paper introduces a shape-rendering method called haptic snake for interacting with virtual objects in air. Haptic snake is composed of serially linked line segments and is controlled using an active contour model known as a snake algorithm. Through an interface controlled using haptic snake, the user can feel a virtual presence in a 3D space from the changes in its shape and the force exerted from the movement of the interface. For the further work, kinesthetic feedback structure will be developed and justified to develop ungrounded mobile haptic interface.

Haptics in a social network service: Tweeting with motion for sharing physical experiences

To augment tangible information into current social network systems (SNSs), this paper proposes an algorithm that generates force data from the users hand gestures. The input modality defined in this paper is based on gesture information in the form of an acceleration profile in that at times it describes the current status of a user better than text-based content. For the physical representation of a motion update, corresponding force vectors in a Cartesian coordinate system are calculated with the proposed linear equation. Given the experimental results, it is predicted that the proposed physical logging and rendering scheme will provide a physical experience in mediated social connections.