Seung-Jong Kim

Magnetically suspended centrifugal blood pump with a self bearing motor.

A magnetically suspended centrifugal blood pump with a self bearing motor has been developed for long-term ventricular assistance. A rotor of the self bearing motor is actively suspended and rotated by an electromagnetic field without mechanical bearings. Radial position of the rotor is controlled actively, and axial position of the rotor is passively stable within the thin rotor structure. An open impeller and a semi-opened impeller were examined to determine the best impeller structure. The outer diameter and height of the impeller are 63 and 34 mm, respectively. Both the impellers indicated similar pump performance. Single volute and double volute structures were also tested to confirm the performance of the double volute. Power consumption for levitation and radial displacement of the impeller with a rotational speed of 1,500 rpm were 0.7 W and 0.04 mm in the double volute, while those in the single volute were 1.3 W and 0.07 mm, respectively. The stator of the self bearing motor was redesigned to avoid magnetic saturation and improve motor performance. Maximum flow rate and pressure head were 9 L/min and 250 mm Hg, respectively. The developed magnetically suspended centrifugal blood pump is a candidate for an implantable left ventricular assist device.

Real-time lip synchronization between text-to-speech (TTS) system and robot mouth

Lip synchronization is one of the most important technologies in the field of intelligent robotics. The natural and precise lip synchronization of robots could contribute to the improvement of human robot interaction and communication. In this paper, we designed a lip synchronization system for intelligent face robots using a text-to-speech system and robot mouth module. By applying several suggested lip synchronization control methods to this robot, we developed a reliable and high-performance robot lip synchronization system. Then, the overall performance of this system was verified through the experiments.

A novel two-dimensional locomotion scheme of a micro-robot with only a uniform magnetic field.

This paper presents a novel motion control method of a micro-robot for biomedical applications. The proposed micro-robot is composed of a permanent magnet with oblique magnetization, and the electromagnetic actuation (EMA) system consists of only two pairs of Helmholtz coils arranged at a right angle on a horizontal plane. While conventional systems generally use the magnetic field gradient for the propulsion, the proposed system uses only a uniform magnetic field. By virtue of these strategies, we can make the system smaller and reduce the power consumption compared to the pre-existing EMA systems. To verify the feasibility of the proposed system, basic experiments and trajectory tracking were performed under different environments.

Cortical activities during a stand to sit movement using fNIRS

Recently, a functional near-infrared spectroscopy (fNIRS) is frequently reported optical brain imaging method from the standpoint of clinical feasibility. This paper was aimed at examining whether fNIRS can be an appropriate brain imaging modality for checking the progress of rehabilitation treatments or not. Two healthy adults performed the given task. Stand to sit task was offered in this study. The results showed that stand to sit movement commonly activated the medial primary motor cortex and primary sensory motor cortex. A fNIRS accurately pointed the brain activity coincided with neurophysiological evidences which were commonly accepted. The results from this study we saw the possibility of the utilizing NIRS into the field of rehabilitation medicine and may contribute to better understanding how motor executions can be expressed into cortical activations.

Eye motion generation in a mobile service robot ‘SILBOT II’

Face of a robot capable of facial expression has a complex structure inside consisting of many actuators, sensors, and other parts. Specially, eyes and its neighbor elements such as upper/lower eyelids, cameras and eyelids, are very densely arranged. In this paper, a compact eyeball module is suggested which is driven with Teflon tube enveloped metal wires, so that one directional motion can be made with one wire pushed or pulled by a motor. And the cylindrical and ball-type pivot parts are used in ends of the tubes and wires, so as to permit their rotation during eye movement. The performance of the suggested module is verified through the comparison between experimental and analytical results. The results are well matched with each other and the degree of positioning precision is also good.

Pan-tilt Motion Generation of Robot Eye by Using a Pair of Push-pull Wires

This paper introduces a robot eye module, of which two degree-of-freedom motions, i.e. panning and tilting, are driven by a pair of wires. The main feature of the module is that each wire can generate push-pull motion without buckling. It is thanks to a Teflon tube which guides the path of the moving wire. End points of the tube and wire have pivot elements so that a smooth push-pull motion is produced even when the end point of wire is moved by eye rotation. This mechanism helps the eye module to be very compact. In this paper, the structure of the robot eye module is introduced in detail, and the required motor angles for a certain direction of eye line are investigated analytically and experimentally.