• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.318-322
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• 1996

This paper presents a technique to control a robot which has a flexible manipulator moving in a vertical plane. The flexible manipulator is modeled as an Euler-Bernoulli beam. Elastic deformation is represented using the assumed modes method. A comparison function which satisfies all geometric and natural boundary conditions of a cantilever beam with an end mass is used as an assumed mode shape. Lagrange's equation is utilized for the development of a discretized model. A control algorithm is developed using a simple PID control technique. The proportional, integral and derivative control gains are determined based on the dominant pole placement method and tuned to show no overshoot and having a short settling time. The effectiveness of the developed control scheme is showed experimentally. In the position control experiment, three different end masses are used. The experimental results shows little overshoot, no steady state error, and less than 2.5 second settling time in case of having an end mass which is equivalent to 45% of the total system weight. Also the residual vibration of the end point is effectively controlled.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.3
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• pp.198-208
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• 2001

In this paper, vibration suppression of an elastic beam fixed on a moving cart and carrying a fixed or moving mass is considered. A modified pulse sequence method with RIC(Robust Internal-loop Compensator) is proposed to suppress the single model residual vibration and to get accurate positioning of the beam-mass-cart system. The performance of the proposed input preshaping method is compared with that of the previous ones through simulations and experiments. Using the proposed method, it is able to suppress the initial vibration of the beam-mass-cart system carrying a concentrated mass. Accurate PTP(point-to-point) positioning of the moving mass without residual vibration is also obtained experimentally by modifying the proposed pulse sequence method. Finally, the proposed input preshaping method is applied successfully to the system to follow square trajectories of the moving mass without residual vibration.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.11
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• pp.34-41
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• 1997

This paper presents a technique to control a very flexible robot moving in a vertical plane. The flexible robot is modeled as an Euler-Bernoulli beam. Elastic deformation is approximated using the assmed modes method. A comparison function which satisfies all geometric and natural boundary conditions of a cantilever beam with an end mass is used as an assumed mode shape. Lagrange's equation is utilized for the development of a discretized model. A control algorithm is developed using a simple PID cnotrol tech- nique. The proportional, integral and deivative control gains are determined based on the dominant pole placement method and tuned to show no overshoot and no steady state error, and short settling time. The effectiveness of the developed control scheme is showed in the hub angular diaplacement control experiment. Three different end masses are uned in the experiment. The experimental results show that developed control algorithm is very effective showing little overshoot, no steady state error, and less than 2.5 second settl- ing time in case of having an end mass which is equivalent to 45% of the manipulator mass. Also the experimental results show that the residual vibration fo the end point is effectively controlled.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.9
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• pp.1025-1031
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• 2011

Take-out robots used for handling of the plastic parts manufactured with the injection mold are usually the gantry type that consists of long and thin links, The performance of the take-out robot is determined by the speed of the motion and the positioning accuracy to grab the part out of the mold, As the speed of the robot increases the flexure in the links of the take-out robot becomes more significant and it results in more residual vibration, The residual vibration deteriorates the positioning accuracy and compels the operator to slow down the motion of the robot. The typical method to reduce the vibration in the robot requires stiffening the links and/or slowing down the robot, Vibration control could achieve the desired performance without increasing the manufacturing cost or the operation cost that would be incurred otherwise, Considering the point-to-point nature of the task to be performed by the take-out robot the time-delay command (or input) shaping filter approach would be the most effective control method to be adopted among a few available control schemes. In this paper a direct adaptive command shaping filter (ACSF) algorithm has been modified and applied to design the optimal command shaping filters for various configuration of the take-out robot. Optimal filters designed by ACSF algorithm have been implemented on a take-out robot and the effectiveness of the designed filters in terms of vibration suppression has been verified for multiple positions of the robot.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.9
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• pp.807-813
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• 2016

Recently, a spherical pendulum attached to an end-effector of a robot manipulator has been frequently used for a test bed of residual vibration suppression control in a multi-dimensional motion. However, there was no automatic tracking system to detect the current bob position on-line, and there was inconvenience to not be able to store the bob position in real time and plot the trajectory. In this study, we developed a two-dimensional, real-time bob-detecting system using a digital USB camera, of which the key is hardware component design and software C programming for fast image processing and interfacing. The developed system was applied to residual vibration suppression control of a two-dimensional spherical pendulum that is attached at the end-effector of a two degree-of-freedom SCARA robot, and the effectiveness of the developed system has been demonstrated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.7 s.100
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• pp.871-877
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• 2005

This paper proposes a new modeling scheme to describe the hysteresis between input voltage and displacement of piezoelectric actuators in the inchworm. From the experimental analysis of Piezoelectric actuator behaviors. the hysteresis characteristics including residual displacement can be modeled by second order functions of a maximum Input voltage and preload. Various experiments are performed to demonstrate the effectiveness and validation of the proposed modeling scheme.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1C
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• pp.43-52
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• 2006

Despite several constitutive models have been proposed and applied, it is still difficult to choose a suitable model and to estimate adequate analysis parameters. Furthermore, a cyclic shear behavior under the volume change caused by the seepage is more complex. None of the constitutive model is available at present in the expression of the cyclic behavior of soil under an additional volume change condition by seepage. Therefore, a new geotechnical hybrid simulation system which can control the pore water immigration was developed. The system enables a quantitative evaluation of the residual deformation such as lateral spreading and settlement caused by the liquefaction. The seismic responses in a one-dimensional slightly inclined multilayered soil system are taken into consideration, and the soils are governed by both equation of motion and the continuity equation. Furthermore, the estimation and the selection of the soil parameter for the representation of the strong nonlinearity of the material are not required, because soil behaviors under the earthquake motions are directly introduced instead of a numerical soil constitutive model. This paper presents the concept and specifications of the system. By applying the system to an example problem, the permeability effect on the seismic response during cyclic shear is studied. The importance of the volume change characteristics of sandy soil during and after cyclic shear is shown in conclusion.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.10
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• pp.749-757
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• 2002

Excessive vibration in flexible structures is a problem encountered in many different fields, causing fatigue of structural components. Passive techniques, though sometimes limited in their capabilities, have been used in the past to attenuate vibrations. Recently active techniques have been developed to enhance vibration control performance beyond that provided by their passive counterparts. Most often, the focus of active control methods has been to suppress structure displacements. In cases where vibration results in structure failures, displacement suppression may not be the best choice of control approaches (it can, in fact, increase dynamic loads which would be even more harmful to supports) . This paper presents two optimal control methods for attenuating steady state vibrations in flexible structures. One method minimizes shaft displacements while another minimizes dynamic reaction forces. The two methods are applied to a model of a typical flexible structure system and their results are compared. It is found that displacement minimization can increase loads, while load minimization decreases loads.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1126-1131
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• 2001

Excessive vibration in rotating machinery is a problem encountered in many different fields, causing such difficulties as fatigue of machinery components and failure of supporting bearings. Passive techniques, though sometimes limited in their capabilities, have been used in the past to attenuated vibrations. Recently active techniques have been developed to provide vibration control perform beyond that provided by their passive counters. Most often, the focus of active control methods has been to suppress rotating machinery displacements. In cases where vibration results in bearing failures, displacement suppression may not be the best choice of control approaches (it can, in fact, increase dynamic bearing loads which would be even more harmful to bearings). This paper presents two optimal control methods for attenuating steady state vibrations in rotating machinery. One method minimizes shaft displacements while the other minimizes dynamic bearing reaction forces. The two methods are applied to a model of a typical rotating machinery system and their results are compared. It is found that displacement minimization can increase bearing loads, while bearing load minimization, on the other hand, decreases bearing loads.

• Journal of Aerospace System Engineering
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• v.12 no.3
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• pp.86-96
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• 2018

The High Agility and Remote Control Camera System Can-Satellite ($HA+RC^2S$ CanSat) proposed in this study is a satellite designed by the authors of this work and submitted as an entry in the 2017 CanSat competition in Goheung gun, Jeonnam, Korea. The primary mission of this work is to develop a high agility camera system (HACS) that can obtain high quality images in the air. This objective is achieved by using a tuned mass damper (TMD) to attenuate the residual vibration that occurs immediately after rotating the camera. The secondary objective is to obtain a self-image of CanSat in the air using a remote control self-camera system (RCSS) that is wirelessly controlled using a joystick from a ground station. This paper describes the development process of the $HA+RC^2S$ CanSat, including mission definition, system design, manufacturing, function and performance tests carried out on the ground, and final launch test.