Jong-Ho Han

Sound Source Tracking Control of a Mobile Robot Using a Microphone Array

To follow a sound source by a mobile robot, the relative position and orientation of the sound source from the mobile robot have been estimated using a microphone array. In this research, the difference among the traveling times of the sound source to each of three microphones has been used to calculate the distance and orientation of the sound source from the mobile robot which carries the microphone array. The cross-correlation between two signals has been applied for detecting the time difference between two signals, which provides reliable and precise value of the time difference comparing to the conventional methods. To generate the tracking direction to the sound source, fuzzy rules are applied and the results are used to control the mobile robot in a real-time. The efficiency of the proposed algorithm has been demonstrated through the real experiments comparing to the conventional approaches.

A 3D Map Building Algorithm for a Mobile Robot Moving on the Slanted Surface

This paper proposes a 3D map-building algorithm using one LRF (Laser Range Finder) while a mobile robot is navigating on the slanted surface. There are several researches on 3D map buildings using the LRF. However most of them are performing the map building only on the flat surface. While a mobile robot is moving on the slanted surface, the view angle of LRF is dynamically changing, which makes it very difficult to build the 3D map using encoder data. To cope with this dynamic change of the view angle in build 3D map, IMU and balance filters are fused to correct the unstable encoder data in this research. Through the real navigation experiments, it is verified that the fusion of multiple sensors are properly performed to correct the slope angle of the slanted surface. The effectiveness of the balance filter are also checked through the hill climbing navigations.

A Mobile Robot Estimating the Real-time Moving Sound Sources by using the Curvature Trajectory

It is suggested that the curvature trajectory be used to estimate the real-time moving sound sources and efficiently the robot estimating the sound sources. Since the target points of the real-time moving sound sources change, the mobile robot continuously estimates the changed target points. In such a case, the robot experiences a slip phenomenon due to the abnormal velocity and the changes of the navigating state. By selecting an appropriate curvature and navigating the robot gradually by using it, it is possible to enable the robot to reach the target points without having much trouble. In order to recognize the sound sources in real time, three microphones need to be organized in a straight form. Also, by applying the cross-correlation algorithm to the TDOA base, the signals can be analyzed. By using the analyzed data, the locations of the sound sources can be recognized. Based on such findings, the sound sources can be estimated. Even if the mobile robot is navigated by selecting the gradual curvature based on the changed target points, there could be errors caused by the inertia and the centrifugal force related to the velocity. As a result, it is possible to control the velocity of both wheels of the robot through the velocity PID controller in order to compensate for the slip phenomenon and minimize the estimated errors. In order to examine whether the suggested curvature trajectory is appropriate for estimating the sound sources, two mobile robots are arranged to carry out an actual experiment. The first robot is moved by discharging the sound sources, while the second robot recognizes and estimates the locations of the discharged sound sources in real time.

Haptic Joystick Implementation using Vibration Pattern Algorithm

Abstract: This research proposes a vibration pattern algorithm to implement the haptic joystick to control a mobile robot at the remote site without watching the navigation environment. When the user cannot watch the navigation environment of the mobile robot, the user may rely on the haptic joystick solely to avoid obstacles and to guide the mobile robot to the target. To generate vibration patterns, there is a vibration motor at the bottom of the joystick which is held by the user to control the motion direction of the mobile robot remotely. When the mobile robot approaches to an obstacle, a pattern of vibration is generated by the motor, and by feeling the vibration pattern which is determined by the relative position of the mobile robot to the obstacle, the user can move the joystick to avoid the collision to the obstacle for the mobile robot. To generate the vibration patterns to convey the relative location of the obstacle near the mobile robot to the user, Fuzzy interferences have been utilized. To measure the distance and location of the obstacle near the mobile robot, ultrasonic sensors with the ring structure have been adopted and they are attached at the front and back sides of the mobile robot. The precise location of the obstacle is obtained by fusing the multiple data from ultrasonic sensors. Effectiveness of the proposed algorithm has been verified through the real experiments and the results are demonstrated. Keywords: mobile robot, haptic joystick, ultrasonic sensor, vibrator feedback, haptic feedback, fuzzy interferences I. 서론 최근 로봇산업이 발전하면서 다양한 분야에서 로봇이 사용되고 있다. 특히 우주 탐험이나 사고현장, 원자로내부의 청소와 같은 인간이 직접 접근하기 어렵고 현재 상황을 확인할 수 없는 위험한 환경에서 사용될 수 있는 원격제어분야의 필요성이 크게 부각되고 있다[1,2]. 원격제어는 로봇에 장착된 다양한 센서 정보를 통하여 외부에서 사용자가 주변 환경을 인식하고 판단하여 제어하는 분야이다[4]. 사용자가 주변 환경을 직접 보면서 제어한다는 장점이 있지만 원거리에 위치한 사용자가 원격제어용 로봇의 비전 센서로부터 전송 받은 영상정보를 눈으로 보고 판단하고, 이를 다시 로봇에게 제어명령을 전송하는 과정에서 문제가 발생하게 된다[3]. 이는 로봇에서 영상정보를 제공하는 비전 센서의 화각(view angle)에 관련된 문제로서 비전 센서를 통해 사용자에게 전송되는 영상정보에 보이지 않는 사각지대가 존재하는 것이다. 이러한 사각지대에 장애물이 존재할 경우 로봇이 장애물에 충돌할 가능성이 존재하게 된다[3]. 그래서 사각지대에 대한 문제를 해결하기 위해 초음파 센서 등의 거리측정 센서를 이용하여 장애물의 존재 유무 및 장애물과의 거리를 측정하여 문제점을 보완하는 방법으로 연구를 하였다. 사용자가 파악할 수 없는 사각지대정보를 로봇이 거리측정 센서를 통해 인지된 장애물에 대한 정보를 사용자에게 전달해야 한다[2]. 전달 방법으로는 영상정보에 장애물 인지사항에 대한 정보를 표현하는 방법을 주로 사용 하게 된다. 하지만 이 방법은 사용자가 주행 영상에 집중하여 미쳐 확인하지 못할 수 있고, 또한 사용자가 영상에 출력된 정보만을 가지고 어떤 상황인지를 판단하기 어려운 상황이 존재하게 된다. 이러한 문제를 해결하기 위하여 다양한 방법들이 연구가 되었는데 그 중에서 조이스틱을 이용한 햅틱의 기능을 이용하여 사용자가 장애물에 대한 정보를 파악하여 대응할 수 있도록 하는 연구가 많이 진행되고 있다. 하지만 사용자가 볼 수 없는 환경에서는 아직까지 연구가 진행된 사례가 많이 없으므로 본 논문에서는 사용자 인지형 햅틱 조이스틱을 개발하여 사용자가 볼 수 없는 환경에서 연구를 하고자 한다. 우리가 알고 있는 햅틱은 사용자가 주로 사용하는 입력 장치를 통해 촉각, 힘 그리고 운동감 등을 느끼게 하는 기술로서 사용자가 직접 진행하지 않아도 그 상태에 대한 촉각이나 힘 그리고 운동감 등을 간접적으로 느낄 수 있게 해주며 로봇과의May 20, 2013 상호작용이 가능하도록 하는 기술을 말한다. 여기서 우리는 촉각에 기여한 모터의 진동으로 사람이 간접적으로 느낄 수 있도록 구현을 하였다[5-8]. 본kr/jmlee@pusan.ac.kr) 논문에서는 사용자 인지형 햅틱 조이스틱을 이용하여 이동로봇을 제어하였으며 이동로봇이 주행 중에 장애물을 인지하게 되면 각각의 상황을 조이스틱 제어기에 전달하고, 조이스틱 제어기는 상황에 따라 일정한 진동 패턴을 만들어 사용자가 알 수 있게 하였다. 이러한 진동패턴은 모스부호를

Sound-Source Tracking and Obstacle Avoidance System for the Mobile Robot

In this paper, the study for the obstacle avoidance of the sound-source tracking mobile robot is introduced. By using the cross-correlation, it is possible to estimate the time difference for sound waves reaching more than two sound-source obtaining devices. Also, through the sound-source obtaining devices and carrying out the geometric interpretation, the location of each sound-source can be found. Based on the suggested application of the motion algorithm, when the mobile robot is in motion, it creates the virtual repulsive force with any obstacle, while applying the virtual attraction force with the reference point in order to avoid obstacles more smoothly and effectively.

De-noising filter study of the sound-source using the DWT

In this paper, the de-noising filter study of the sound-source using the DWT is introduced. We suggest the de-noising filter using the Discrete Wavelet Transform (DWT). The DWT has been performed to remove out the noises from the signals. In order to confirm the performance of suggested filtering algorithm, we estimate the distance and angle from the microphone to the sound-source and compare the filtered signal to the original signal. To calculate the distance and angle, we use the cross-correlation that is possible to estimate the time difference for sound waves reaching more than two sound-source obtaining devices. Also, through the sound-source obtaining devices and carrying out the geometric interpretation, the location of each sound-source can be found.

Obstacle Avoidance of a Moving Sound Following Robot using Active Virtual Impedance

Abstract: An active virtual impedance algorithm is newly proposed to track a sound source and to avoid obstacles while amobile robot is following the sound source. The tracking velocity of a mobile robot to the sound source is determined byvirtual repulsive and attraction forces to avoid obstacles and to follow the sound source, respectively. Active virtual impedanceis defined as a function of distances and relative velocities to the sound source and obstacles from the mobile robot, which isused to generate the tracking velocity of the mobile robot. Conventional virtual impedance methods have fixed coefficients forthe relative distances and velocities. However, in this research the coefficients are dynamically adjusted to elaborate the obstacleavoidance performance in multiple obstacle environments. The relative distances and velocities are obtained using a microp honearray consisting of three microphones in a row. The geometrical relationships of the microphones are u tilized to estimate therelative position and orientation of the sound source against the mobile robot which carries the microphone array. Effectivenessof the proposed algorithm has been demonstrated by real experiments.Keywords: microphone array, location, obstacle avoidance, mobile robot, sound source

PD-Fuzzy control for the velocity of mobile robot using the haptic joystick

In this paper, the mobile robot attached ultrasonic sensor, it can be obtained from measured ultrasonic sensor data according to the distance of obstacle using haptic joystick, it can be precisely controlled the velocity of mobile robot. The haptic is that can be composed vibration at the bottom of the joystick to attach small motor, the haptic can be implemented using the voltage of motor change according to the distance information from ultrasonic sensor. It composed the master (Haptic joystick) and slave (mobile robot) for the experiment. We studied the velocity of mobile robot control.

Tracking of a moving object by following the sound source

To follow a sound source by a mobile robot, the relative position and orientation of the sound source from the mobile robot have been estimated using a microphone array. In this research, the difference among the traveling times of the sound source to each of three microphones has been used to calculate the distance and orientation of the sound source from the mobile robot which carries the microphone array. The cross-correlation between two signals has been applied for detecting the time difference between two signals, which provides reliable and precise value of the time difference comparing to the conventional methods. To generate the tracking direction to the sound source, fuzzy rules are applied and the results are used to control the mobile robot in a real-time. The efficiency of the proposed algorithm has been demonstrated through the real experiments comparing to the conventional approaches.

Efficiency Analysis Solar Cell of the Dynamic Boat`s by SPA

Recently, worldwide government policy is pursuing saving energy and preservation. add to this, the solar cells are getting the spotlight nonpolluting energy source, using a variety of products for solar cell. in this paper, we`ll make solar tracking system for suitable of dynamic boat. we knew that general boats are using fixed solar cell, it`s first time to use tracking system of solar cells for boats so it is hard to application. To solve this problem in this paper we use to a magnetic compass and GPS for suitable solar tracking system of dynamic movement and to analyze fixed and tracking solar system. frist. solar tracking device is designed two-axis control system. one-axis control system is taken a magnetic compass for making efficiency defence solar tracking sensor, two-axis control system apply GPS latitude and longitude data for SPA(Solar position algorithm) so we know the azimuth and altitude. it analyze data value of accuracy comparison from result. so the proposed algorithm confirm to have validity.