• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.19 no.4
• /
• pp.476-484
• /
• 2010

Precise positioning stages are often employed for precise machinery. For the purpose of vibration isolation, these precise positioning stages are mounted on a heavy base structure which is supported by compliant springs. Then the base structure is subjected to residual vibration due to the reactive force and vertical moving load induced by the stage motion. This paper investigates the vibration behavior of a positioning stage base and the associated vibration suppression technique. A dynamic model is developed to investigate the base vibration due to the reactive force and moving load effects by the moving stage. An input shaping technique is also developed to suppress the residual vibrations in base structures. Simulations and experiments show that the developed dynamic model adequately represents the base vibration and that the proposed input shaping technique effectively removes the residual vibrations from the positioning stage base.

• Journal of the Semiconductor & Display Technology
• /
• v.16 no.2
• /
• pp.98-105
• /
• 2017

In the display industry, the residual vibration of the transfer robot can increase the process time and cause the breakage of the glass substrate, which is critical to productivity of display manufacturing. In this paper, the natural frequencies of transfer robot are analyzed by finite element method. On the basis of the analyzed data, we investigated the response characteristics of input shaping control with or without the glass presence on the hand of the transfer robot using MATLAB program, and compared with the current response characteristics of input shaping control applied to the industry. Based on this, we suggest an optimal residual vibration control method for the practical application in display industry.

• 대한공업교육학회지
• /
• v.31 no.2
• /
• pp.364-380
• /
• 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
• /
• v.26 no.9
• /
• pp.88-95
• /
• 2009

Input shaping has been a very effective control method for reducing payload swing in industrial bridge and gantry cranes. However, conventional input shapers often degrade performance when applied to tower cranes because of the nonlinear coupled dynamics between rotational and radial motions in tower cranes. To alleviate this problem, a new input shaper for tower cranes is developed by means of dynamic modeling, analysis and optimization. This work investigates the tower crane dynamics along with parameters of the tower crane varied. A performance index for input shaper design is proposed so as to reduce the coupled residual vibration of a tower crane using only rotational motion of tower crane. The proposed new input shaper is verified to be effective through simulations and experiments.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.26 no.3
• /
• pp.313-319
• /
• 2017

This study presents a genetic algorithm (GA) to design a PID controller systematically for an inchworm operated by piezoelectric actuators. The performance index considering overshoot and settling time is adopted to search an optimal PID gain using GA. The piezoelectric actuator shows nonlinear characteristics including hysteresis and residual displacement. The PID feedback system combined with an integrator is used to improve the ability of tracking the complex input signals and suppressing the steady state error. The PID controller tuned by GA can track the various motion contours effectively. However, the PID controller shows an improper residual vibration under the application of high-frequency square input. The input shaper combined with the feedback system can overcome this limitation of the PID controller.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.21 no.11
• /
• pp.2828-2835
• /
• 1996

In this paper we propose a new shaping algorithm which can control the shaping delay and the output buffer size based on the leaky bucket counter with a threshold value. This paper assumes that input traffic of the proposed shaping algorithm is the worst case traffic tolerated by the continuous leaky bucket algorithm and claracterizes traffic patterns that can depart from our shaping algorithm. We also compare shaping delay and output buffer size of the proposed algorithm with the existing shaping algorithm without a threshold value. Our results show that the proposed shaping algorithm can easily manage the shaping delay and output buffer size than any other mechanism.

• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.4
• /
• pp.100-106
• /
• 2009

The current tendency toward light weight and fast machines has lead to a need to suppress vibration of flexible dynamic systems. Input shaping is an efficient tool to eliminate transient and residual vibration caused by motion of these systems. This paper proposes a new formulation of the design method for multi-mode input shapers to eliminate residual vibration in flexible dynamic systems. The essence of the proposed method is to minimize the number of impulses to be n+1 for n-mode input shapers. This paper also suggests a solution procedure to solve the complex-valued nonlinear matrix equation for the input shapers. The proposed method is applied to two-mode input shapers. This paper discusses characteristics of several input shapers obtained under the same condition. Simulations and experiments show that the proposed method is very useful for designing multi-mode input shapers.

• The Transactions of the Korea Information Processing Society
• /
• v.2 no.5
• /
• pp.667-676
• /
• 1995

In ATM traffic multiplexing, the cell clumping and the cell dispersion are occured due to the cell delay variance(CDV) which changes the traffic characteristics. These cell variances increase the burstiness of t.he cell streams and make the network congested. The function of the traffic shaping is necessary to transmit the input streams into the networks or into the traffic policing schemes with some intevals. Most of the existing studies regard the input traffics as the traffic with the identical characteristics. In this study, the traffic shaping is processed by considering the traffic characteristICS with t.he loss-sensitive traffic and the delay-sensitive traffic. The traffic shaping model and the traffic shaping algorithm which considers the" characteristics of input streams have been presented. The traffic effect On t.he CDV size is also studied. The proposed scheme is compared to Virtual Scheduling Algorithm(VSA) and the efficiency of the proposed scheme is evaluated. According to the simulation results, t.he mean delay is decreased about 12% in delay-sensitive traffic and the traffic burstiness is decreased about 11 % in loss-sensitive traffic.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.18 no.1
• /
• pp.3-10
• /
• 2008

In this paper, the optimal command input is considered in order to minimize the residual vibrations of a flexible cantilever beam when the beam simply changes its position by translation or rotation. Although a cantilever beam has many modes of vibration, it is shown that the consideration of the first mode is sufficient in this case. Thus, the problem becomes a single-degree-of-freedom system subjected to a ground excitation. Two simple methods are proposed to find the optimal command input based on the shock response spectrum (SRS). The first method is the simplest and can be applied to lightly damped cases, and the second method is applicable to more general problems. The second method gives almost the same results as the input shaping method. However the proposed method gives a easier and clearer control strategy.

• Journal of the Korean Society for Precision Engineering
• /
• v.28 no.8
• /
• pp.959-965
• /
• 2011

This paper presents the dynamic modeling and vibration suppression methods for axially deploying beams subjected to gravity. A modal modeling method is employed to develop the lateral vibration model for axially deploying beams. Simulation is made to validate the proposed model as well as to investigate the dynamics of axially deploying beams. This paper rigorously investigates the gravity effect as a source of vibration for axially deploying beams. In order to suppress lateral vibration for deploying beams, the moving speed command is modified by using the input shaping method, Experiments are also performed to prove the proposed vibration suppression method. The simulations and experiments show that the proposed modeling and input shaping methods are effective for the dynamic analysis and vibration suppression of axially deploying beams subjected to gravity.