• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.410-410
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• 2000

Impedance control is recognised as one of the most proper control scheme to carry out the assembly tasks, since it can control the dynamic relationship between the manipulator and environment directly. However, it is well known that the contact force cannot be controlled directly using the impedance control. Also impedance parameters should be properly defined depending on the task to be performed. We propose a new position based impedance control, which has self-adjusted impedance parameters and can control the contact force explicitly, Impedance parameters, as time-varying parameters, are adjusted automatically based on the measured contact force and the position error during the task. A proposed algorithm was implemented on the peg-in-hole task with the industrial manipulator. We shows the effectiveness of proposed control method experimentally.

• International Journal of Control, Automation, and Systems
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• v.3 no.3
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• pp.461-468
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• 2005

This paper proposes a wheel-assembly automation system, which assembles a wheel into a hub of a vehicle hung to a moving hanger in a car manufacturing line. A macro-micro manipulator control strategy is introduced to increase the system bandwidth and tracking accuracy to ensure insertion tolerance. A camera is equipped at the newly designed wheel gripper, which is attached at the center of the end-effector of the macro-micro manipulator and is used to measure position error of the hub of the vehicle in real time. The redundancy problem in the macro-micro manipulator is solved without complicated calculation by assigning proper functions to each part so that the macro part tracks the velocity error while the micro part regulates the fine position error. Experimental results indicate that tracking error satisfies the insertion tolerance of assembly $({\pm}1mm)$, and thus it is verified that the proposed system can be applied to the wheel assembly task on a moving hanger in the manufacturing line.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1854-1858
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• 2007

The reliability assurance with respect to the test procedure and results of the out-pile mechanical performance test for the nuclear fuel assembly is an essential task to assure the test quality and to get a permission for fuel loading into the commercial reactor core. For the case of vibration test, which is carried out to obtain basic dynamic characteristics of the fuel assembly, proper management and appropriate calibration of instruments and devices used in the test, various efforts to minimize the possible error during the test and signal acquisition process are needed. Additionally, the deep understanding both of the theoretical assumption and simplification cation for the signal processing/modal analysis and of the functions of the devices used in the test were highly required. Finally, to verify the test result to represent the accurate natural characteristics of the structure, the proper correlation analysis between the theoretical and experimental method has to be carried out. In this study, the overall procedure and result of lateral vibration test for the fuel assembly's mechanical characterization were briefly introduced. A series of measures to assure and improve the reliability of the vibration test were discussed.

• Journal of Korean Institute of Industrial Engineers
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• v.17 no.2
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• pp.51-61
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• 1991

This paper presents a heuristic method for the Assembly Line Balancing(ALB) of the large-sized product. In the ALB problem of the large-sized product such as bus and truck, the assignments of the Related Task Groups(RTG), the same side tasks, and team tasks should be considered. In this paper, a new concept of the RTG and two kinds of assignment rules are proposed to resolve the above considerations. The first assignment rule allots the RTG with the constraint of the same side tasks to the station while the second allots the RTG to the station, relaxing the above constraint to increase the applicability of the method. An assignment rule for team tasks is also presented. The benefits of the method are to improve work methods, to give more job satisfaction to workers, and to allow greater flexibility in the design of assembly lines.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.6
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• pp.517-521
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• 2016

General industrial robots are difficult to use for precision assembly because they are operated based on position control. Their position accuracy is also usually higher than the assembly clearance (several tens of ${\mu}m$). In previous researches, force control was suggested as a robotic assembly solution. However, this method is difficult to apply in reality because of speed and cost problems. The RCC provides high speed, but applications are limited because the compliance is fixed, and it cannot detect an assembly condition during a task. A variable passive compliance device (VPCD) was developed herein. The VPCD can detect the assembly condition during tasks. This device can provide proper compliance for successful assembly tasks. The pneumatic system and the Stewart platform with an LVDT sensor were applied for measuring the displacement and variable compliance, respectively. The concept design and analysis were conducted to prove the effectiveness of the developed VPCD.

• TTA Journal
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• s.48
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• pp.172-180
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• 1996

지난 4월, 향후 유럽 정보사회를 겨냥한 효율적 표준화 추진을 위해 TFIG(Task Force Implementation Group)에서 제안한 ETSI(European Telecommunications Standards Institute)의 표준화 조직구조 개편 요구에 따라 기존 ETSI의 기술 총회(TA : Technical Assembly)는 지난 25차 회의를 마지막으로 그간의 기술총회 활동을 마감하고 새로이 25명으로 구성된 이사회(Board) 체계로 변경되어진다. 이에 본 고에서는 지난 96년 10월에 열렸던 마지막 기술총회 참석 결과를 정리하고, 새로운 ETSI 조직 구조 변경에 따른 변화를 살펴보고자 한다.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.3
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• pp.298-308
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• 2000

In this paper a new two-arm cooperative assembly(or insertion) algorithm is proposed. As a force-guided control method for the cooperative assembly the adaptive accommodation controller is adopted since it does not require any complicated contact state analysis nor depends of the geometrical complexity of the assembly parts. Also the RMRC(resolved motion rate control) method using a relative jacobian is used to solve inverse kinematics for two manipulators. By using the relative jacobian the two cooperative redundant manipulators can be formed as a new single redundant manipulator. Two arms can perform a variety of insertion tasks by using a relative motion between their end effectors. A force/torque sensing model using an approximated penetration depth calculation a, is developed and used to compute a contact force/torque in the graphic assembly simulation . By using the adaptive accommodation controller and the force/torque sensing model both planar and a spatial cooperative assembly tasks have been successfully executed in the graphic simulation. Finally through a cooperative assembly task experiment using a humanoid robot CENTAUR which inserts a spatially bent pin into a hole its feasibility and applicability of the proposed algorithm verified.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.1
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• pp.99-106
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• 2003

Uninterrupted power supply has become indispensable during the maintenance task of active electric power lines as a result of today's highly information-oriented society and increasing demand of electric utilities. The maintenance task has the risk of electric shock and the danger of falling from high place. Therefore it is necessary to realize an autonomous robot system. In order to realize these tasks autonomously, the there dimensional position of target object such as electric line and the stand of insulator must be recognized accurately and rapidly. The insertion task of an electric line into a sleeve is selected as the typical task of the maintenance of active electric power distribution lines in this paper. A modified hough transform is applied to the recognition of the center of electric line and optimal target position calculation method is newly derived in order to recognize the center 3 dimensional position of the electric line. By the proposed method, it is proved that the center position of the electric line can be recognized without respect to the noise of image and the shape of electric lines and the insertion task of an electric tine is realized.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.412-412
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• 2000

This paper presents a task teaching method for off-line programming of a multi-robot system. Teaching commands were developed in order to simplify a complex teaching process, to shorten the setup time for new working environment and to have flexibility for changes in working environment. Four teaching commands can be used to automatically generate trajectories of an end-effector of the robot in electronics assembly line. The robots used in the work cell are a four-axis SCARA robot and six-axis articulated robot. Each robot is controlled in a independent way while objects, working environment and robots are modeled in corresponding modules, respectively. The off- line programming system developed uses OpenGL for a smooth graphic effect in Window s where three dimensional CAD data can be leaded for graphical modeling.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.17 no.4
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• pp.213-220
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• 2024

This paper proposes an optimization strategy for performing Federated Learning between devices and edge clouds using WebAssembly (WASM). The proposed strategy aims to maximize efficiency by conducting partial training on devices and the remaining training on edge clouds. Specifically, it mathematically describes and evaluates methods to optimize data transfer between GPU memory segments and the overlapping of computational tasks to reduce overall training time and improve GPU utilization. Through various experimental scenarios, we confirmed that asynchronous data transfer and task overlap significantly reduce training time, enhance GPU utilization, and improve model accuracy. In scenarios where all optimization techniques were applied, training time was reduced by 47%, GPU utilization improved to 91.2%, and model accuracy increased to 89.5%. These results demonstrate that asynchronous data transfer and task overlap effectively reduce GPU idle time and alleviate bottlenecks. This study is expected to contribute to the performance optimization of Federated Learning systems in the future.