• The Journal of Korea Robotics Society
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• v.2 no.3
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• pp.221-226
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• 2007

A robust position-sensing system is proposed in this paper for ubiquitous mobile robots which move indoor as well as outdoor. The Differential GPS (DGPS) which has position estimation error of less than 5 m is a general solution when the mobile robots are moving outdoor, while an active beacon system (ABS) with embedded ultrasonic sensors is selected as an indoor positioning system. The switching from the outdoor to indoor or vice versa causes unstable measurements on account of the reference and algorithm changes. To minimize the switching time in the position estimation and to stabilize the measurement, a robust position-sensing system is proposed. In the system, to minimize the switching delay, the door positions are stored and updated in a database. The reliability and accuracy of the robust positioning system based on DGPS and ABS are verified through the real experiments using a mobile robot prepared for this research and demonstrated.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.606-610
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• 2004

In this paper, we would like to explain about the structure analysis of wheel set as variation of contact position between wheel and rail. Measurement of interacted force between wheel and rail is necessary for running safety evaluation as important factor of derailment mechanism. It's necessary to running safety evaluation of rolling stock. Wheel unload and lateral force change as variation of contact position between wheel and rail. Interacted force between wheel and rail got as each contact position through computer simulation. This is necessary process as first research for evaluation of derailment phenomenon and running safety.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1205-1211
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• 2004

We propose a train position estimation method for automatic train control system. The accurate train position should be continuously feedback to control system for safe and efficient operation of trains in railway. In this paper, we propose the sensor fusion method integrating the tachometer, the transponder, and the doppler sensor for estimation of train position. The external sensors(transponder, doppler sensor) are used to compensate for the error of internal sensor(tachometer). The Kalman filter is also applied to reduce the measurement error of the sensors. Simulation results are then presented to verify the usefulness of the proposed method.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.207-209
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• 2005

Recently, the use of IPMSM is coming to be active, in many industrial applications. In sensorless drive of IPMSM, it is important to know the exact information of the initial rotor position, because the wrong estimation of the initial rotor position brings about the decrease of the starting torque, or a temporary reverse revolution, In addition, PMSM is necessary to use the accurate information of the inductance for the precise torque control owing to the reluctance torque. In this paper presents initial rotor position estimation method and, measure method of the each-axis inductance. And to minimize the speed estimations error, the estimated speeds are compensated by using an instantaneous reactive power in synchronously rotating reference frame.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.70-74
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• 1998

This paper describes a method for recognition of two-dimensional position of an object by use of aerial ultra-sonic sensor and signal processing technique, which would become a help for blind person or self-mobile robot. First, we have developed a method for measuring the time difference between the transmitted and the received burst wave by use of one ultrasonic transmitter and three receivers. Secondly, a new method is developed for measuring the distance to an object by use of M-sequence correlation method. Thirdly, a measurement method to obtain the position of an object is described by use of phase-arrayed ultrasonic sensor, which gives us a wide-range position determination in a short time.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.507-510
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• 2003

In this paper, optical sensor system using PSD(Position Sensitive Detection) is proposed to obtain the three dimensional position of moving markers attached to human body. To find the coordinates of an moving marrer with stereo vision system, two different sight rays of an moving marker are required. Usually, those are acquired with two optical sensors synchronized at the same time. PSD sensor is used to measure the position of an incidence light in real-time. To get the three-dimension position of light source on moving markers, a conventional camera calibration method are used. In this research, we realized a low cost motion capture system. The proposed system shows high three-dimension measurement accuracy and fast sampling frequency.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.2
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• pp.89-95
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• 2017

In this paper, we suggest the method for a mobile robot to move safely from an initial position to a goal position in the wide environment like a building. There is a problem using odometry encoder sensor to estimate the position of a mobile robot in the wide environment like a building. Because of the phenomenon of wheel's slipping, a encoder sensor has the accumulated error of a sensor measurement as time. Therefore the error must be compensated with using other sensor. A vision sensor is used to compensate the position of a mobile robot as using the regularly attached light's panel on a building's ceiling. The method to create global path planning for a mobile robot model a building's map as a graph data type. Consequently, we can apply floyd's shortest path algorithm to find the path planning. The effectiveness of the method is verified through simulations and experiments.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.493-498
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• 1993

This paper proposes a high precision measurement technique to obtain the height of gage block. The proposed technique is consisted of two steps : In the first step, laser position transducer and electric micrometer are adopted to obtain a coarse value of the height of gage block, and then, second, heterodyne laser interferometry is adopted to acquire the precision value. The experiment results show that accuract in the order of a few nanometer is achieved for the gage blacks of as high as a few millimeter.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.276-279
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• 2003

The phase change upon reflection from target surfaces in white-light interferometer induces measurement errors when target surfaces are composed of dissimilar materials. We prove that this phase change on reflection considered of the polarization of the white-light causes the shift of both envelope peak position and fringe peak position of several tens of nanometer. In addition, we propose a new equation of white-light interference fringe pertinent to the polarization of source.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.592-595
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• 1986

This paper presents a mobile of robot (for the blind) commanded by written course route on MAP. Its locomotion module is composed of PWM motor driving unit, wheel's rotation measurement unit and display and keyboard unit. In algorithm, "COMMAND" and "NEXT PREDICTED POSITION" for locomotion are computed from the MAP and the next position is compared with the measured one. Also, locomotion method for the convenience of the blind is discussed and experimentally demonstrated. In the experiment, the average speed of robot is 0.4m/sec and the computation error of the map is negligible.