Jong-Il Bae

Development of a high performance single-phase voltage regulator composed of 3 arms bridge

Regulation of load voltage in single-phase application is becoming an important issue for critical loads. This paper presents a novel high performance single-phase voltage regulator which has a common arm between the AC/DC and DC/AC power converters and adopts an appropriate switching strategy. As a result, the proposed voltage regulator can reduce the number of switching devices and system loss, while maintaining the capabilities of power factor correction and good output voltage regulation. In addition, novel low-cost AC capacitor using two DC capacitors is also presented. Therefore, the whole voltage regulator system can be more compact, simpler and less expensive than conventional designs. The fully digital controller is designed using a high-speed DSP, and the proposed system is validated through experimental results.

Interacting mobile robots for tele-operation system using the World Wide Web

This paper discusses the interacting mobile robots for tele-operation system using the World Wide Web. The main components of this paper are user interface, networking, simulation, and robot control. The standard graphic user interface (GUI) is implemented using Java Programing language. The Web browser is used to integrate the virtual environment and the standard GUI (Java applet) in a single user interface. Users can access a dedicated WWW server and download the user interface. Java application has been developed to communicate and control the robot using RF communication. In addition to users direct control a fuzzy logic control is applied. We propose the use of FLC (fuzzy logic controllers) that incorporate expert knowledge in terms of linguistic rules. Experiments have shown that such fuzzy controlled mobile robots can have a better performance than a fine-tuned PID-controlled mobile robots.

System identification using generalized orthonormal basis

A linear time-invariant model can be described either by a parametric model or by a nonparametric model. Nonparametric models, for which a priori information is not necessary, are basically the response of the dynamical system such as impulse response model and frequency models. Parametric models, such as transfer function models, can be easily described by a small number. In this paper, we will expand and generalize the orthogonal functions as basis functions for dynamical system representations. To this end, use is made of balanced realizations as inner transfer functions. The orthogonal functions can be considered as generalizations of, for example, the pulse functions, Laguerre functions, and Kautz functions, and give rise to an alternative series expansion of rational transfer functions. It is shown how we can exploit these generalized basis functions to increase the speed of convergence in a series expansion.

Intelligent control of a robot manipulator by visual feedback

We present a new approach to visual feedback control using image-based visual servoing with stereo vision. In order to control the position and orientation of a robot with respect to an object, a new technique is proposed using binocular stereo vision. The stereo vision enables us to calculate an exact image Jacobian not only at around a desired location, but also at other locations. The suggested technique can guide a robot manipulator to the desired location without needing such a priori knowledge as the relative distance to the desired location or a model of the object, even if the initial positioning error is large. We describes a model of stereo vision and how to generate feedback commands. The performance of the proposed visual servoing system is illustrated by a simulation and by experimental results, and compared with the conventional method for an assembling robot.

Development of the flexible observation system for a virtual reality excavator using the head tracking system

Operating excavator on the risk surroundings is not safe for human to control on site. Consequently, automatic excavator called Field Robot has been researched to protect the workers from the hazardous environments. The remote excavation system is required to perform in such environments. This paper presents the study on remote control system for the Field Robot and augmented reality vision for user using head tracker system. The design of the remote control system that consist Remote Station and Filed Robot. In Remote Station, user can send the control commands through wireless communication. Besides, the Inertial Measurement Unit (IMU) sensor is integrated in a head mounted display (HMD) to track the motion of humans head. These signals are transferred to the pan/tilt motor controller and to operate the motion of the CCD camera following the movement of operators head. The Field Robot is also contributed and some experiments are carried out to prove the feasibility of the proposed system.

Development of an unmanned vehicle driving system by MR sensor

By using the information obtained from output of MR (magneto resistive) sensors for an unmanned vehicle system which is used in the local position system, we develop an algorithm that decides the distance and directions between the guide line that is made by a series of magnets and MR sensors of the vehicle. We propose simple vehicle dynamics and PD control that can minimize the number of sensors in the unmanned vehicle driving system.