Laehyun Kim

A haptic-rendering technique based on hybrid surface representation

A novel haptic rendering technique using a hybrid surface representation addresses conventional limitations in haptic displays. A haptic interface lets the user touch, explore, paint, and manipulate virtual 3D models in a natural way using a haptic display device. A haptic rendering algorithm must generate a force field to simulate the presence of these virtual objects and their surface properties (such as friction and texture), or to guide the user along a specific trajectory. We can roughly classify haptic rendering algorithms according to the surface representation they use: geometric haptic algorithms for surface data, and volumetric haptic algorithms based on volumetric data including implicit surface representation. Our algorithm is based on a hybrid surface representation - a combination of geometric (B-rep) and implicit (V-rep) surface representations for a given 3D object, which takes advantage of both surface representations.

Meshes on fire

We present a new method for the animation of fire on polyhedral surfaces. Using the notion of discrete straightest geodesics, we evolve fire fronts directly on the surface of arbitrarily complex objects. Animator control and motion complexity is achieved by driving the fire motion using multi-scale turbulent wind fields and geometric quantities. Our model also supports adaptivity of the fire fronts, multiple simultaneous fires, and merging of multiple fires. This new technique produces convincing simulations at interactive rates even on a low-end PC, greatly increasing the productivity of the animation design process.

A universal remote control with haptic interface for customer electronic devices

We introduce a new universal remote control that gives easy-to-control interface for home devices such as TV, video/audio player, room lighting and temperature control. In order to use conventional remote controls, people need to understand complex instruction manuals and remember functions assigned to buttons. In addition, the button-based control does not provide an intuitive interface so the user presses a button several times to browse information and has difficulty in searching the right button among many buttons. Our universal remote control addresses these limitations by using a touch screen, a force-feedback dial knob, and two buttons instead of many buttons. We suggest an example scenario to interact with a conventional TV set, room lighting, and air conditioner using our universal remote control. The result of a user study to evaluate the usability of the device shows that the universal remote control is very efficient and intuitive interface to control customer electronics devices.

An electronic traveler aid for the blind using multiple range sensors

This paper presents a novel electronic travel aid, called iSONIC, which can help a visually impaired person walk around more safely. Attached to a conventional white cane, the iSONIC detects obstacles at head-height that cannot be covered by a traditional cane and gives warnings in the forms of vibration or sound to avoid dangerous situations. We developed an algorithm to restrict the sensing range to reduce confusing and unnecessary detections and a method to remove the sensing errors due to the impact of ground tapping. In addition to obstacle detection, the iSONIC give information of object color and the environmental brightness when the user wants to know.

Design of haptic interface for brickout game

This paper introduces a haptic interface for brick games. Conventionally the game user uses mouse or keyboard to play the brick game. However, these input devices do not provide intuitive interface for the game and any tactile feedback to the user. We use a haptic dial to add tactile feedback to enhance game effects in addition to visual and sound effects. The user changes the position of the paddle by spinning the dial knob and feels various tactile feedbacks according to the game context. Tactile feedbacks include friction, jog dial, barrier, detent, and any combinations of these effects which are programmed based on the amount, frequency, and direction of torque along the rotational path. These effects are used as either penalties or useful tools. The proposed haptic dial interface makes the game more fun and gives a very intuitive interface to the game user.

Which motor cortical region best predicts imagined movement

In brain-computer interfacing (BCI), motor imagery is used to provide a gateway to an effector action or behavior. However, in contrast to the main functional role of the primary motor cortex (M1) in motor execution, the M1s involvement in motor imagery has been debated, while the roles of secondary motor areas such as the premotor cortex (PMC) and supplementary motor area (SMA) in motor imagery have been proposed. We examined which motor cortical region had the greatest predictive ability for imagined movement among the primary and secondary motor areas. For two modes of motor performance, executed movement and imagined movement, in 12 healthy subjects who performed two types of motor task, hand grasping and hand rotation, we used the multivariate Bayes method to compare predictive ability between the primary and secondary motor areas (M1, PMC, and SMA) contralateral to the moved hand. With the distributed representation of activation, executed movement was best predicted from the M1 while imagined movement from the SMA, among the three motor cortical regions, in both types of motor task. In addition, the most predictive information about the distinction between executed movement and imagined movement was contained in the M1. The greater predictive ability of the SMA for imagined movement suggests its functional role that could be applied to motor imagery-based BCI.

A tangible user interface with multimodal feedback

Tangible user interface allows the user to manipulate digital information intuitively through physical things which are connected to digital contents spatially and computationally. It takes advantage of human ability to manipulate delicate objects precisely. In this paper, we present a novel tangible user interface, SmartPuck system, which consists of a PDP-based table display, SmartPuck having a built-in actuated wheel and button for the physical interactions, and a sensing module to track the position of SmartPuck. Unlike passive physical things in the previous systems, SmartPuck has built-in sensors and actuator providing multimodal feedback such as visual feedback by LEDs, auditory feedback by a speaker, and haptic feedback by an actuated wheel. It gives a feeling as if the user works with physical object. We introduce new tangible menus to control digital contents just as we interact with physical devices. In addition, this system is used to navigate geographical information in Google Earth program.

EEG response varies with lesion location in patients with chronic stroke.

BackgroundBrain activation differs according to lesion location in functional magnetic resonance imaging (fMRI) studies, but lesion location-dependent electroencephalographic (EEG) alterations are unclear. Because of the increasing use of EEG-based brain-computer-interface rehabilitation, we examined lesion location-dependent EEG patterns in patients with stroke while they performed motor tasks.MethodsTwelve patients with chronic stroke were divided into three subgroups according to their lesion locations: supratentorial lesions that included M1 (SM1+), supratentorial lesions that excluded M1 (SM1-), and infratentorial (INF) lesions. Participants performed three motor tasks [active, passive, and motor imagery (MI)] with supination and grasping movements. The hemispheric asymmetric indexes, which were calculated with laterality coefficients (LCs), the temporal changes in the event-related desynchronization (ERD) patterns in the bilateral motor cortex, and the topographical distributions in the 28-channel EEG patterns around the supplementary motor area and bilateral motor cortex of the three participant subgroups were compared with those of the 12 age-matched healthy controls.ResultsThe SM1+ group exhibited negative LC values in the active and MI motor tasks, while the other patient subgroups exhibited positive LC values. Negative LC values indicate that the ERD/ERS intensity of the ipsilateral hemisphere is higher than the contralateral hemisphere, whereas positive LC values indicate that the ERD/ERS intensity of the contralateral hemisphere is higher than the ipsilateral hemisphere. The LC values of SM1+ and healthy controls differed significantly (rank-sum test, p < 0.05) in both the supination and grasping movements in the active task. The three patient subgroups differed distinctly from each other in the topography analysis.ConclusionsThe hemispheric asymmetry and topographic characteristics of the beta band power patterns in the patients with stroke differed according to the location of the lesion, which suggested that EEG analyses of neurorehabilitation should be implemented according to lesion location.

Assessment of Cognitive Engagement in Stroke Patients From Single-Trial EEG During Motor Rehabilitation

We propose a novel method for monitoring cognitive engagement in stroke patients during motor rehabilitation. Active engagement reflects implicit motivation and can enhance motor recovery. In this study, we used electroencephalography (EEG) to assess cognitive engagement in 11 chronic stroke patients while they executed active and passive motor tasks involving grasping and supination hand movements. We observed that the active motor task induced larger event-related desynchronization (ERD) than the passive task in the bilateral motor cortex and supplementary motor area (SMA). ERD differences between tasks were observed during both initial and post-movement periods (p <; 0.01). Additionally, differences in beta band activity were larger than differences in mu band activity (p <; 0.01). EEG data was used to help classify each trial as involving the active or passive motor task. Average classification accuracy was 80.7±0.1% for grasping movement and 82.8±0.1% for supination movement. Classification accuracy using a combination of movement and post-movement periods was higher than in other cases (p <; 0.05). Our results support using EEG to assess cognitive engagement in stroke patients during motor rehabilitation.

Prototype modular capsule robots for capsule endoscopies

Capsule endoscopy allows clinicians to wirelessly examine the small intestine using a capsule equipped with a miniscule camera. However, it has intrinsic limitations such as a lack of controlled capsule locomotion and limited therapeutic functions inside the gastrointestinal (GI) track. Recently, several researches have been conducted to prototype robotic capsules that have a self-propelling mechanism by integrating modern technologies. To routinely use in a clinical setting, several technical challenges, including size constraint of the capsule, locomotion mechanism, and stable power source, should be addressed. In this paper, we introduce a prototype of a modular robotic capsule system, which is designed to distribute the functional burdens among multiple robotic capsule modules. For example, active locomotion can be achieved via a collaborative actuation among multiple modules after self-assembly. This novel design was also supplemented with inductive power transmission techniques to wirelessly power the modules. The presented modular, miniature robotic platform may provide a new paradigm for developing multi-function capsule endoscope, with future implications in minimally invasive surgery.