• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1116-1120
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• 2004

In the nuclear power plant, there are several cylindrical vessels such as reactor vessel, pressuriser and so on. The vessels are usually constructed by welding large rolled plates, forged sections or nozzle pipes together. In order to assure the integrity of the vessel, these welds should be periodically inspected using sensors such as ultrasonic transducer or visual cameras. This inspection is usually conducted under water to minimize exposure to the radioactively contaminated vessel walls. The inspections have been performed by using a conventional inspection machine with a big structural sturdy column, however, it is so huge and heavy that maintenance and handling of the machine are extremely difficult. It requires much effort to transport the system to the site and also requires continuous use of the utility's polar crane to move the manipulator into the building and then onto the vessel. Setup beside the vessel requires a large volume of work preparation area and several shifts to complete. In order to resolve these problems, we have developed an underwater mobile robot guided by the laser pointer, and performed a series of experiments both in the mockup and in the real reactor vessel. This paper introduces our robotic inspection system and the laser guidance of the mobile robot as well as the results of the functional test.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.1
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• pp.144-149
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• 2001

There are many types of seam tracking methods actually used in industrial spot. Lately, Non-contact sensor technics are mostly used because non-contact sensor has more advantage than contact sensor in many parts. This paper also concerned about fiber sensor a kind of non-contact sensor. X-Y robot and fiber sensor scan the seam tracking to be weld. After scanning, X-Y robot moves the first working point of being scanned and welding starts automatically. It makes an experiment on some types of Seam tracking like straight line tracking, leaned line tracking and curved line tracking to confirm how well the fibers sensor tracks the seam pass to be weld. And the seam pass that had been tracked was welded by inverter $CO_2$ voiding machine.

• Journal of Drive and Control
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• v.12 no.3
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• pp.1-10
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• 2015

In this paper, the authors propose a method to easily recognize and reproduce the robot motion made by an operator. This method is targets for applications similar to painting and welding, and it is based on a process of that identifies a family of plants, by control design and by conducting an experimental evaluation. In this study, the models and controllers for all joints of 3DOF robot system are obtained individually. And a robust control system for motion control of the individual joints is designed based on $H_{\infty}$ control framework. An experimental comparison is made between the proposed control method and existing PID control method. And the results indicate that the proposed designing method is more efficient and useful than conventional method.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.4
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• pp.16-23
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• 2021

Currently, 6-axis articulated robots are used throughout the industry because of their 6-dof (degrees of freedom) and usability. However, 6-axis articulated robots have a fixed base and their movements are limited by the rotational operating range of each axis. If the angle of the 2-axis additional axes can be adjusted according to the position and orientation of the end-effector of the 6-axis articulated robot, the effectiveness of the 6-axis articulated robot can be further increased in areas where the angle is important, such as welding. Therefore, in this paper, we proposed a cooperative kinematic inter-operation strategy. The strategy will be verified using the Simulink of MATLABⓇ, an engineering program, and RecurdynⓇ, a dynamic simulation program.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.344-349
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• 2017

Wall-climbing robots have been developed for various purposes, such as cleaning skyscraper windows, maintaining large structures, and welding vessels. Conventional wall-climbing robots use movement systems based on wheels or legs. However, wheeled robots suffer from slipping effects, while legged systems require many actuators and control systems for the complex linkage structure, which also increases the weight of the robot. To overcome these disadvantages, we propose a new wall-climbing robot that walks based on gorilla locomotion. The proposed robot consists of a DC drive motor, a vacuum pump for adsorption, and a micro controller for controlling the system. The performance of the robot was experimentally verified on vertical and horizontal flat surfaces. The robot could be used for various functions in industrial sites or disaster areas.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.2
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• pp.318-323
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• 2013

For fast and accurate motion of 6-axis articulated robot, more noble motion control strategy is needed. In general, the movement strategy of industrial robots can be divided into two kinds, PTP (Point to Point) and CP (Continuous Path). Recently, industrial robots which should be co-worked with machine tools are increasingly needed for performing various jobs, as well as simple handling or welding. Therefore, in order to cope with high-speed handling of the cooperation of industrial robots with machine tools or other devices, CP should be implemented so as to reduce vibration and noise, as well as decreasing operation time. This paper will realize CP motion (especially joint-linear) blending in 3-dimensional space for a 6-axis articulated (lab-manufactured) robot (called as "RS2") by using LabVIEW$^{(R)}$ (6) programming, based on a parametric interpolation. Another small contribution of this paper is the proposal of motion blending simulation technique based on Recurdyn$^{(R)}$ V7 and Solidworks$^{(R)}$, in order to figure out whether the joint-linear blending motion can generate the stable motion of robot in the sense of velocity magnitude at the end-effector of robot or not. In order to evaluate the performance of joint-linear motion blending, simple PTP (i.e., linear-linear) is also physically implemented on RS2. The implementation results of joint-linear motion blending and PTP are compared in terms of vibration magnitude and travel time by using the vibration testing equipment of Medallion of Zonic$^{(R)}$. It can be confirmed verified that the vibration peak of joint-linear motion blending has been reduced to 1/10, compared to that of PTP.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.3
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• pp.113-118
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• 2004

In this paper, we propose a new weaving trajectory algorithm for the arc welding of a articulated manipulator. The algorithm uses the theory of Bezier spline. We make a comparison between the conventional algorithms using Catmull-Rom curve and the new algorithms using Bezier spline. The proposed algorithm has been evaluated based on the MATLAB environment in order to illustrate its good performance. Through simulations, the proposed algorithm can result in high-speed and flexible weaving trajectory planning so that it's trajectory cannot penetrate into a base metal compared to the conventional algorithm using Catmull-Rom curve.

• Journal of Welding and Joining
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• v.14 no.1
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• pp.7-14
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• 1996

3D 기피 현상에 따른 인력난은 이제 국내 산업계 전반에 걸친 커다란 문제가 되었으며, 특히 용접 및 절단 공정에서는 그 정도가 심각한 상황으로 숙련된 기술자 의 확보가 용이하지 않은 상황이다. 따라서 많은 기업에서는 제품의 품질향상과 대량 생산 능력을 갖추기 위해서 용접 및 절단 공정에서의 자동화를 추진하고 있으며, 로봇 을 이용한 방법이 각광을 받고있다. 그러나 이 경우에도 용접용 로봇과 절단용 로봇을 비교하여 보면, 일본의 경우, 절단용으로 출하되는 로봇의 수는 용접용 로봇의 1/70 - 1/100 수준이다. 국내의 경우 최근 들어 용접분야에서의 로봇의 이용은 활성화 되어 있는 편이지만, 절단의 경우는 적용예가 드문 실정이다. 절단용 로봇의 경우 로봇 이용분야가 가장 발달된 일본의 경우도 1988년부터 로봇을 절단용으로 이용하기 시작 하였으며, 그 이용분야도 레이저 절단과 워터젯트 절단에 치중되어 있다. 그러나 현실 적으로 국내 산업현장에는 주로 가스절단이 절단의 주류를 이루고 있는 실정으로, 이에 대한 로봇 응용 시스템의 개발이 시급하다. 대우중공업에서는 가스절단 로봇을 국삭기 Boom측판에 개선가공 공정에 적용하여, 가스절단 분야에의 로봇 적용이라는 가능성을 보여주었으며, 본고에서 그 내용을 소개하고자 한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1138-1141
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• 1995

An arc sensor for seam tracking is developed to automate sub-assembly welding in shipbuilding. We utilize a moving average method, which produces an effect of low-pass filter, to generate the position compensation. Therefore the sensor is able to modify the path of the weld seam in real time. By simplifying the compension process, the tunning time is reduced so that operators react quickly. It turns out that this sensor is highly reliable and it is installed and being used in SHI Keoje shipbuilding yard.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2424-2426
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• 2002

This paper proposes an adaptive control method of partially known system and shows its application result to control for two-wheeled WMR. The controlled system is stable in the sense of Lyapunov stability. To design a tracking controller for welding path reference, an error configuration is defined and the controller is designed to drive the error to zero as fast as desired. Moments of inertia of system are considered to be unknown system parameters. Their values are estimated using update laws in adaptive control scheme. The effectiveness of the proposed controller is shown through simulation results.