• 대한공업교육학회지
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• v.31 no.2
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• pp.364-380
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• 2006

This paper presents a procedure for designing command to maneuver flexible structure with very little residual vibration, even in the presence of modeling errors. For the open loop maneuver, the various shaped profiles using multiple step inputs delayed in time are considered for robustness and compared with the responses of rigid body and flexible body in virtue of simulations and experiments. Input shaping generates vibration-reducing shaped commands through convolution of an impulse sequence with the desired command. A flexible model with a cylindrical hub and four symmetric appendages is considered to examine the responses to real plant, and to illustrate the effectiveness of the proposed shapers. The appendages are long and flexible, leading to low frequency vibration under any control action. It is shown by a series of simulation that a properly designed feedback controller with input shaper performs well, as compared with open loop controller with input shaper. The control objective is to achieve a fast settling time of residual vibration to flexible structure and robustness (insensitivity)to plant uncertainty, to eliminate residual vibration.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.3 s.192
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• pp.67-75
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• 2007

This paper deals with a problem of vibration suppression of a piezoelectric beam using a self-sensing algorithm. Two methods, which are PPF(positive position feedback) and SRF(strain rate feedback), are considered to suppress a residual vibration of a piezoelectric beam developed during the step positioning of a beam end point. A self-sensing algorithm treated here is basically a strain rate estimator of a beam movement and is to be used for the closed loop control. The efficacy of the proposed idea is evaluated through experiments.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.679-680
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• 2008

• 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.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.7
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• pp.717-724
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• 2013

Industrial cranes are indispensable equipment in heavy industry. However, unwanted vibrations in cranes often cause accidents. Input shaping is widely accepted as a useful tool for removing residual vibration in cranes. A unity magnitude zero vibration (UMZV) input shaper is often used for cranes driven by on-off-type motors. However, although a UMZV input shaper minimizes residual vibration, the input shaper cannot prevent the crane from moving slightly further than expected from the original command. This paper describes an improved method of input shaping that can compensate for position inaccuracies, as well as remove the residual vibration of cranes. Experiments were performed to validate the proposed input-shaping method, illustrated through numerical simulations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.1
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• pp.17-24
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• 2011

It is reported that an intermittently rotating chamber system will improve the ratio of firepower to armament space in the case of mid-calibre automatic guns. However, the parallel index, which is a main component of the system, tends to be torsionally flexible due to the low lateral stiffness of cam followers on the index turret. This may cause the shaft system connecting the turret with the chamber prone to considerable residual torsional vibration so that serious misalignment problems occur during ammunition loading and firing processes. Herein, an electrorhelogical (ER) fluid actuator that can suppress such vibrations and the associated semiactive control algorithm are proposed. By mathematical modeling and computer simulations, the performance of the entire system is proved satisfactory.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.5
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• pp.313-319
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• 2016

It is very important to understand and control the sloshing in a liquid container that is partially filled with liquid. Previous studies focused primarily on the sloshing and resonance caused by sinusoidal excitations, while the present study focuses on understanding and suppressing sloshing in a container that moves rapidly from a given point to another in industrial applications. To achieve this, we first numerically predict the two-phase flow induced by the horizontal movement of a rectangular container. Then we analyze the effects of container-velocity profile (in particular acceleration/deceleration duration) on sloshing. Results show that sloshing is significantly suppressed when the acceleration/deceleration duration is a multiple of the 1st-mode natural period of sloshing.

• Journal of the Korean Society for Railway
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• v.16 no.4
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• pp.278-285
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• 2013

The suppression of residual settlement is required on earthwork sections as concrete track is introduced. Use of pile-slab structure is one of the settlement restraining methods applied on soft ground. The slab distributes the upper embankment load and piles transfer the load from the slab to the stiff ground. While this method is very effective in terms of load transfer, it has not yet been established for dealing with the vibration transfer effects and interaction characteristics between a structure and the ground. It is possible that vibration caused by a moving train load is propagated in the upper embankment, because the slab acts as a reflection layer and waves are multi-reflected. In this present paper, wave propagation generated by a moving train load is evaluated in the time and frequency domains to consider a roadbed structure using an artificial impact load and field measured train load. The results confirmed the wave reflection effect on the pile-slab structure, if the embankment height is sufficient, vibration propagation can be stably restrained, whereas if the height is not sufficient, the vibration amplitude is increased.

• The Journal of Korea Robotics Society
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• v.4 no.3
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• pp.250-256
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• 2009

Suppressing residual vibrations of flexible materials cheaply is an important issue to increase productivity of automated factory using wafer or glass handling robots. In this paper, we present Linux/RTAI-based implementation of input shaping control for reducing residual vibrations of a mechanical system. Experimental results show that residual vibrations of the mechanical system are reduced up to 82% at a point-to-point linear motion.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.4
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• pp.71-78
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• 2007

Input shaping is known to be a very effective tool for suppressing residual vibration without introducing any complicated sensors and feedback control. Real-time input shaping schemes necessitate a process such that the input command is discretized to deal with non-prescribed, real-time input. Thus parameters associated with input command discretization, such as time spacing and duration time, are unknowns which affect the performance of input shaping schemes, especially for small and fast XY stages. This paper investigates the effects of input command discretization parameters, such as time spacing and duration time, on the dynamic performance of XY stages subjected to real-time input shaping. An experimental system is developed which is equipped with an XY stage driven by servo-motors and real-time user command. Experiments are performed to investigate the dynamic performance of XY stage by changing these parameters and to yield a strategy to gain better performance.