• Journal of Information Processing Systems
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• v.13 no.3
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• pp.491-499
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• 2017

In this study, we proposed a new approach to segment ground and nonground points gained from a 3D laser range sensor. The primary aim of this research was to provide a fast and effective method for ground segmentation. In each frame, we divide the point cloud into small groups. All threshold points and start-ground points in each group are then analyzed. To determine threshold points we depend on three features: gradient, lost threshold points, and abnormalities in the distance between the sensor and a particular threshold point. After a threshold point is determined, a start-ground point is then identified by considering the height difference between two consecutive points. All points from a start-ground point to the next threshold point are ground points. Other points are nonground. This process is then repeated until all points are labelled.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.832-837
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• 1991

After many years of proliferation, the nuclear industry is indebted for a formidable consequence, the safe management of spent fuel. Naturally, the high radioactivity involved with such process motivates the development of effective telerobotic systems. Nevertheless, the existing master-slave type of tele manipulators are limited in effectiveness by the human operator's limited sensory and manipulation capabilities. This paper presents the result of a research effort to resolve such problems by assigning the slave manipulator a certain degree of intelligence; sensing and actuation. In the presented system, a perception-action loop is achieved using ultrasonic range sensor and laser distance sensor interfaced with the PUMA 760 industrial robot system, and applied to automating impact wrenching task for unbolting the lid of nuclear spent fuel cask. The perception-action loop performs determination of the cask location, collision avoidance and centering of the impact wrench onto the bolt head. To aid the insertion task and to provide versatility a mounting module consisting of an RCC device and an automatic tool changer is designed and implemented. The performance of the developed system is tested on the model cask and the result is given.

• Annual Conference of KIPS
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• 2016.10a
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• pp.681-682
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• 2016

In this study we propose a novel approach to segment a terrain in two parts: ground and none-ground. The terrain is gained by a multi-channel 3D laser range sensor. We process each vertical line in each frame data. The vertical line is bounded by the sensor's position and a point in the largest circle of the frame. We consider each pair of two consecutive points in each line to find begin-ground and end-ground points. All points placed between a begin-ground point and an end-ground point are ground ones. The other points are none-ground. After examining all vertical lines in the frame, we obtain the terrain segmentation result.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.4
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• pp.119-126
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• 1995

This paper presents a non-contact measuring system using one point measuring method to measure surface profiles of dies and clay models for practical use in the field of production engineering. The system has a laser beam probe similar to a measuring probe in a contact measuring system and CCD linear sensor used to detect 300mm measurement range, displacement of measured surfaces, from an origin. There is no mechanical interference between this measuring system and a measured surface in this system. In this measuring system, it was needed 500-600ms including data processing time to measure one point. The experiments showed that the standard deviation was 800 .mu.m and the reproducibility was also 100-210 .mu. m.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.9
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• pp.669-676
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• 2013

In this study, we introduce a polymer(polyimide) based pressure sensor to measure real-time heart beat and blood pressure. The sensor have been designed with consideration of skin compatibility of material, cost effectiveness, manufacturability and wireless detection. The designed sensor was composed of inductor coils and an air-gap capacitor which generate self-resonant frequency when electrical source is applied on the system. The sensor was obtained with metalization, etching, photolithography, polymer adhesive bonding and laser cutting. The fabricated sensor was shaped in circular type with 10mm diameter and 0.45 mm thickness to fit radial artery. Resonant frequencies of the fabricated sensors were in the range of 91~96 MHz on 760 mmHg pressurized environment. Also the sensor has good linearity without any pressure-frequency hysteresis. Sensitivity of the sensor was 145.5 kHz/mmHg and accuracy was less than 2 mmHg. Real-time heart beat measurement was executed with a developed hand-held measurement system. Possibility of real-time blood pressure measurement was showed with simulated artery system. After installation of the sensor on skin above radial artery, simple real blood pressure measurement was performed with 64 mmHg blood pressure variation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05b
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• pp.62-65
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• 2003

When a mobile robot moves around autonomously without man-made corrupted bye landmarks, it is essential to recognize the placement of surrounding objects especially for self localization, obstacle avoidance, and target classification and localization. To recognize the environment we use many Kinds of sensors, such as ultrasonic sensors, laser range finder, CCD camera, and so on. Among the sensors, ultra sonic sensors(sonar)are unexpensive and easy to use. In this paper, we analyze the sonar data and propose a method to recognize features of indoor environment. It is supposed that the environments are consisted of features of planes, edges, and corners, For the analysis, sonar data of plane, edge, and corner are accumulated for several given ranges. The data are filtered to eliminate some noise using the Kalman filter algorithm. Then, the data for each feature are compared each other to extract the character is ties of each feature. We demonstrate the applicability of the proposed method using the sonar data obtained form a sonar transducer rotating and scanning the range information around a indoor environment.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.3
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• pp.236-241
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• 2008

This paper presents a method to recognize the plane regions for movement of walking robots. When the autonomous agencies using stereo camera or laser scanning sensor is under unknown 3D environment, the mobile agency has to detect the plane regions to decide the moving direction and perform the given tasks. In this paper, we propose a very fast method for plane detection using normal vector of a triangle by 3 vertices defined on a small circular region. To reduce the effect of noises and outliers, the triangle rotates with respect to the center position of the circular region and generates a series of triangles with different normal vectors based on different three points on the boundary of the circular region. The vectors for several triangles are normalized and then median direction of the normal vectors is used to test the planarity of the circular region. The method is very fast and we prove the performance of algorithm for real range data obtained from a stereo camera system.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.5
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• pp.436-441
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• 2009

A fiber optic sensor is prospective to be applied to structural health monitoring. Especially, a fiber Bragg grating(FBG) sensor is one of the most popular sensors for the structural health monitoring. The FBG sensor has several demodulation systems for tracking the shift of the Bragg wavelength. The dynamic bandwidth is dependent on the demodulation system. In this paper, the sensing mechanism is that the slope of the optical spectrum of FBG could be used as its sensitivity when the tunable laser shot the monochromatic laser wavelength at the highest slope point. In this technique, the high sensitivity is guaranteed even though the sensing range is limited. In an example of the application, the composite plate embedding a FBG sensor was manufactured by using an autoclave method and the above sensing mechanism was applied to the composite plate. Firstly, the natural frequencies of the plate were successfully measured by the FBG sensor during the impact hammer test. Secondly, a high-power speaker was used to force the plate to be vibrated at the specific frequency that was one of the natural frequencies. During the shaking, the FBG sensor measures the dynamic characteristics and ESPI was also used to measure the mode shape. From the two dynamic tests, the availability of the FBG sensor system and the ESPI was proven as a technique for measuring the dynamic characteristics of composite structure.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.1
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• pp.125-133
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• 2010

A versatile micro-robotic platform for micro/nano scale assembly has been demanded in a variety of application areas such as micro-biology and nanotechnology. In the near future, a flexible and compact platform could be effectively used in a scanning electron microscope chamber. We are developing a platform that consists of miniature mobile robots and a compact positioning stage with multi degree-of-freedom. This paper presents the design and the implementation of a low-cost and compact multi degree of freedom position sensor that is capable of measuring absolute translational and rotational displacement. The proposed sensor is implemented by using a CMOS type image sensor and a target with specific hole patterns. Experimental design based on statistics was applied to finding optimal design of the target. Efficient algorithms for image processing and absolute position decoding are discussed. Simple calibration to eliminate the influence of inaccuracy of the fabricated target on the measuring performance also presented. The developed sensor was characterized by using a laser interferometer. It can be concluded that the sensor system has submicron resolution and accuracy of ${\pm}4{\mu}m$ over full travel range. The proposed vision-based sensor is cost-effective and used as a compact feedback device for implementation of a micro robotic platform.

• Korean Journal of Optics and Photonics
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• v.7 no.4
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• pp.419-427
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• 1996

Thermally-stabilized fiber-optic current sensors are proposed and demonstrated. The sensor head is made of two coil formers combined perpendicularly. In this sensor head, bending-induced birefringences can be reduced to the level much smaller than those of the single former type because the eigen-axes of the two perpendicular coil formers are made orthogonal to each other. Moreover, thermal variation of the birefringence is also expected to be minimized by the orthogonality of the two polarization eigen-axes. We changed the temperature slowly in the range of 20~45$^{\circ}C$ during 100 minutes. The overall linearity of the sensor is better than 1.2% in the range of 0~1000A. The long-term fluctuation of the sensor is less than 1% when measured for 3 hours at 500A and room temperature. Two orthogonally-polarized laser diodes are combined together to make the incident beam unpolarized. In the signal processing, the signals are separated by two parts and normalized respectively, which minimize the efects of optical fluctuations coming from sources, connectors, etc.