• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.229-232
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• 1996

The position control accuracy of the robot arm is decreased significantly when a long arm robot is operated at high speed. In this case, the robot arm must be modeled as a flexible structure, not a rigid one, and its control system will be necessarily designed with its elastic modes taken into account. In this paper, the vibration control of a one-link flexible robot arm is presented. The robot system consists of a flexible arm manufactured with thin aluminium plate, AC servomotor with a harmonic drive for speed reduction, optical encoder and accelerometer. The system is modeled with limited number of elastic modes, and its parameters are determined from the results of the experiments. The implemented control schemes are LQ control and sliding mode control. The experiments and digital simulations are carried out to test the validity of the system modeling, controller design, and active control implementation.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.399-404
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• 1999

An improved finite element modeling technique is proposed for the assessment of load carrying capacity partilly prestressed concrete beam bridges. Based on the finite element method of analysis, shell and frame elements are utilized to model the slab and beams of the superstructure, respectively. In the modeling of superstructure, the emphasis is placed on the use of rigid link between the middle surface of slab and mid-plane of beam. This paper also includes the comparision of three different equations that used in the calculation of effective moment of inertia for the partially prestressed concrete beams. Numerical analysis is performed for the unstrengthened and strengthened bridges. The obtained results are compared with those of load test for a prototype bridge. Agreement with the numerical solutions by using the proposed method and load test results is generally excellent.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.724-727
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• 1999

In this paper, the direct and indirect neural adaptive controller are combined based on the Lyapunov synthesis approach. The proposed adaptive controller is constructed from RBF neural network and a set of fuzzy IF-THEN rules. And the weighting parameters are adjusted on-line according to some adaptation law for the purpose of controlling the plant to track a given trajectory. In this scheme, fuzzy IF-THEN rules are used to decide the combined weighting factor. It is shown that all the signals in the closed-loop system are uniformly bounded under mild assumptions. The effectiveness of the proposed control scheme is demonstrated through the control of one-link rigid robotics manipulator.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.2
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• pp.220-227
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• 1999

The position control accuracy of a robot arm is significantly deteriorated when a long slender arm robot is operated at a high speed. In this case, the robot arm needs to be modeled as a flexible structure, not a rigid one, and its control system needs to be designed with its elastic modes taken into account. In this paper, the vibration control scheme of a one-link flexible manipulator using adaptive input shaper in conjunction with PID controller is presented. The robot consists of a flexible arm manufactured with a thin aluminium plate, an AC servo motor with a harmonic drive for speed reduction, an optical encoder and an accelerometer. On-line identification of the vibration mode is done using the pruned decimation-in-time FFT algorithm to estimate the parameter of the input shaper. Experimental results of the flexible manipulator with a PID controller and input shaper are provided to show the effectiveness of the advocated controllers.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.455-460
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• 2000

Impact occurs when the vibration amplitude of a mechanical component exceeds a given clearance size. Examples of these mechanical systems include impact dampers, gears, link mechanism, rotor rub, and so on. The vibration due to impact has strong non-linear characteristics, which cannot be predicted by usual linear analysis. The designs of mechanical systems with impacts should be done on the basis of overall dynamic characteristics of the systems. In this paper, the nonlinear behaviors of a beam with a periodically moving support and a rigid stop are investigated numerically and experimentally. The beam vibration with impact is modeled by the equations of motion containing piecewise linear restoring forces and by the coefficient of restitution, respectively. Experimental and numerical results show jump phenomena and higher-harmonic vibrations. The effects between the increase of stiffness during impact and the coefficient of restitution are investigated through the comparison of the experimental and numerical results.

• International Journal of Precision Engineering and Manufacturing
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• v.5 no.3
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• pp.77-84
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• 2004

A robust optimal control design is proposed in this study for rigid robotic systems under the unknown loads and the other uncertainties. The uncertainties are reflected in the performance index, where the uncertainties are bounded for the quadratic square of the states with a positive definite weighting matrix. An iterative algorithm is presented for the determination of the weighting matrix required for necessary robustness. Computer simulations have been done for a weight-lifting operation of a two-link manipulator and the simulation results shows that the proposed algorithm is very effective for a robust control of robotic systems.

• Journal of the Korean Institute of Navigation
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• v.21 no.1
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• pp.109-118
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• 1997

In this paper, applications of multilayer neural networks to control of flexible robot beam are considered. The multilayer nerual networks can be used to approximate any continuous function to a desired degree of accuracy and the weights are updated by Gradient Method. When a flexible beam is rotated by a motor through the fixed end, transverse vibration may occur. The motor torque should be controlled insuch a way that the motor rotates by a specified angle, while simultaneously stabilizing vibration of the flexible manipulators so that is arrested as soon as possbile at the end of rotation. Accurate control of lightweight beam during the large changes in configuration common to robotic tasks requires dynamic models that describe both rigid body motions, as well as the flexural vibrations. Therefore, a linear dynamic state-space model of for a single link flexible robot beam is derived and PD controller, LQP controller, and inverse dynamical neural networks controller are composed. The effectiveness the proposed control system is confirmed by computer simulation.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.4
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• pp.24-31
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• 1998

In this study, a procedure is presented for the dynamic analysis of a multibody tracked vehicle system. The planar vehicle model used in this investigation is assumed to consist of two kinematically decoupled subsystems. i.e., the chassis subsystem and track subsystem. The chassis subsystem includes the chassis frame, sprocket, idler and rollers, while the track subsystem is represented as a closed kinematic chain consisting of rigid links interconnected by revolute joints. The nonlinear contact force modules describing the interaction between track links, and sprocket, idler, rollers and ground will be developed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1992.10a
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• pp.133-138
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• 1992

The three dimensional analysis of Framed-Tube structures is neither easy nor efficient because of longer computational time, large memory requirement, tedious input preparation and bulky output. An efficient analysis model for framed-tube structure is proposed in this study. The proposed model can save the computational effort by using the assumption of the rigid floor diaphragm effect and matrix condensation technique. Moreover, it is develpoed by assembling two dimensional frames using the link degrees of freedom which are temporary used to satisfy the vertical displacement compatibility at the corners of a framed-tube. The accuracy and the efficiency of this analytical model is established by comparing with the results using the computer code SAPIV which is based on the three dimensional finite element model.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.251-258
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• 2001

Cable and membrane structures can be classified as a unstable structure in the view point of shape determination process. An unstable stucture at the initial state generally cannot take a role as the resistance for the external force. Therefore, there should be a stabilizing process to get the stable state of a structure and it is necessary to visualize the shape finding from unstable state to stable state. In this paper, a numerical method of stabilizing procedure for the link structures is presented. The structures are assumed to have rigid movements and thus only changing of the topology of member is considered during the analysis. The generalized inverse matrix and the principle of minimum potential energy are used in the process. Illustrative examples are presented and the results show good convergence.