• Title/Summary/Keyword: Flexible Mode

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Sliding mode control of a single-link flexible arm with uncertainties (불확실성을 갖는 단일 링크 탄성 Arm의 슬라이딩 모드 제어)

  • 신호철;김정식;최승복;정재천
    • 제어로봇시스템학회:학술대회논문집
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    • 1993.10a
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    • pp.546-551
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    • 1993
  • A new robust sliding mode controller is formulated for the tip position control of a single-link flexible manipulator with parameter variations. After establishing the plant model characterized by a noncollocated uncertain control system, a sliding surface which guarantees stable sliding mode motion is synthesized in an optimal manner. The surface is then modified to adapt arbitrarily given initial conditions. A discontinuous control law associated with the modified surface is designed by restricting that velocity state variables are not available from direct sensor measurements. Using the proposed control law favorable system responses are accomplished through shortening the reaching phase of state trajectory without increasing maximum control torque as well as undesirable chattering. Furthermore, a low sensitiveness to uncertainties is obtained from inherent salient properties of the proposed control system. Computer simulations are undertaken in order to demonstrate these superior control performance characteristics to be accrued from the proposed methodology.

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Nonlinear observer for flexible joint robots (유연한 관절 로보트에 대한 비선형 관측기)

  • 김윤재;임규만;함철주;함운철
    • 제어로봇시스템학회:학술대회논문집
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    • 1993.10a
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    • pp.648-653
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    • 1993
  • This paper presents an nonlinear observer scheme for flexible joint robot manipulators. This nonlinear observer scheme is based on the sliding mode method. Sliding controllers have recently been shown to feature excellent robustness and performance properties for specific classes of nonlinear tracking problems. Dynamic equations of flexible joint robot manipulators are derived from the Euler-Lagrange equations by forming the corresponding Lagrangian. Simulation results are presented to show the validness of the proposed nonlinear observer scheme.

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Modeling of flexible stick balencer and controller design (Flexible stick balencer에 대한 modeling과 제어에 관한 연구)

  • Seo, Ki-Won;Cho, Hwang
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10b
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    • pp.233-236
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    • 1996
  • This paper describes a liner state-space model for a flexible stick balencer. The method employed to generate the model utilizes a separable formulation of assumed modes to represents the transverse displacement due to bending Lagrangian dynamics are applied to determine the kinetic and potential energies for the system. The resultant dynamic equations are then organized into a state space model and linearized using Taylor series expansion method. A minimum order observer is designed to estimate unmeasurable states.

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Pixel isolated liquid crystal mode for flexible displays

  • Lee, Hyun-Gi;Jung, Jong-Wook;Kim, Jae-Hoon
    • 한국정보디스플레이학회:학술대회논문집
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    • 2003.07a
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    • pp.615-618
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    • 2003
  • We developed a new device structure using anisotropic phase sepraration from liquid crystals (LCs) and polymer composite materials for flexible display applications. In the device, the LC molecules are isolated in pixels where LCs are surrounded by polymer layers. These devices show very good mechanical stability against external pressure. The electro-optic characteristics and the mechanical stability of the devices are discussed in view of the flexible display applications.

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Removal of Suspended Solids Using a Flexible Fiber Filter in a Recirculating Aquaculture System (유연성 섬유사 여과기를 이용한 순환여과식 양식장의 부유고형물 제거)

  • Choi, Kwang-Soo
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.40 no.2
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    • pp.73-78
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    • 2007
  • The suitability of a flexible fiber filter for removing suspended solid (SS) in a recirculating aquaculture system was evaluated. This study focused on variation in the performance with a change in filtering time, influent water quality, and filtering mode duration. The particle distribution diagram of the filter effluent showed that the number of particles bigger than $5-8{\mu}m$ decreased dramatically, and the removal efficiency exceeded 80%. Although the removal efficiencies of SS and chemical oxygen demand (COD) were dependent on the quality of the influent, the SS and COD concentrations of the effluent were not affected by the influent concentrations. This was despite the deterioration if water quality after feeding in the rearing tank. The performance of the filter was not affected by the filtering mode duration, feeding conditions, or filtering time. The SS concentration and turbidity of the recirculating-type rearing tank were 30% and 50% lower, respectively, than of the a non-recirculating-type rearing tank under the same operating conditions. The flexible fiber filter was applicable to a recirculating aquaculture system that uses plenty of seawater, based on its low filtering resistance $(2kg_f/cm^2)$, high flux $(330m^3/m^2/hr)$, and high fine particle removal efficiency (80%, $5-8{\mu}m$).

Finite Element Forced Response of a Spinning Flexible HDD Disk-spindle System Considering the Asymmetry Originating from Gyroscopic Effect and Fluid Dynamic Bearings (자이로스코픽 효과와 유체 동압 베어링에 의한 비대칭성을 고려한 회전 유연 디스크-스핀들 시스템의 유한요소 강제 진동 해석)

  • Park, Ki-Yong;Jang, Gun-Hee;Seo, Chan-Hee
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.20 no.10
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    • pp.915-922
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    • 2010
  • This paper presents an efficient method for determining the forced response of a spinning flexible disk-spindle system supported by fluid dynamic bearings(FDBs) in a computer hard disk drive(HDD). The spinning flexible disk-spindle system is represented by the asymmetric finite element equations of motion originating from the asymmetric dynamic coefficients of the FDBs and the gyroscopic moment of a spinning disk-spindle system. The proposed method utilizes only the right eigenvectors of the eigenvalue problem to transform the large asymmetric finite element equations of motion into a small number of coupled equations, guaranteeing the accuracy of their numerical integration. The results are then back-substituted into the equations of motion to determine the forced response. The effectiveness of the proposed method was verified by comparing it with the responses from the classical methods of mode superposition with the general eigenvalue problems, and mode superposition with modal approximation. The proposed method was shown to be effective in determining the forced response represented by the asymmetric finite element equations of motion of a spinning flexible disk-spindle system supported by FDBs.

Investigation on the Generalized Hydrodynamic Force and Response of a Flexible Body at Different Reference Coordinate System (기준 좌표계에 따른 탄성체의 일반화 파랑 하중 및 응답에 대한 연구)

  • Heo, Kyeonguk;Choi, Yoon-Rak
    • Journal of the Society of Naval Architects of Korea
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    • v.58 no.6
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    • pp.348-357
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    • 2021
  • In this paper, the generalized hydrodynamic force and response of a flexible body are calculated at different reference coordinate systems. We generalize the equation of motion for a flexible body by using the conservation of momentum (Mei et al., 2005). To obtain the equations in the generalized mode, two different reference coordinates are adopted. The first is the body-fixed coordinate system by a rigid body motion. The other is the inertial coordinate system which has been adopted for the analysis. Using the perturbation scheme in the weakly-nonlinear assumption, the equations of motion are expanded up to second-order quantities and several second-order forces are obtained. Numerical tests are conducted for the flexible barge model in head waves and the vertical bending is only considered in the hydroelastic responses. The results show that the linear response does not have the difference between the two formulations. On the other hand, second-order quantities have different values for which the rigid body motion is relatively large. However, the total summation of second-order quantities has not shown a large difference at each reference coordinate system.

The Vibration Control of Flexible Manipulators using Adaptive Input Shaper (적응 입력다듬기를 이용한 유연한 조작기의 진동제어)

  • 신효필;정영무;강이석
    • 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.

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The vibration control of Flexible Manipulator using Parallel Fuzzy controller and Reference Trajectory Command (병렬퍼지 제어기와 기준궤적신호를 이용한 유연한 매니퓰레이터의 진동제어)

  • 박양수;박윤명
    • Journal of the Institute of Convergence Signal Processing
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    • v.3 no.1
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    • pp.61-66
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    • 2002
  • A fuzzy control strategy is described which is utilized to control the joint angle and tip deflection in single flexible manipulator. In this paper, an existing model for a single flexible manipulator is used for the initial development of an FLC. One FLC is designed to govern the joint angle of the manipulator as it is rotated from one position to another, and the second FLC is designed to attenuate the tip deflection which result from joint angle body motion. Reference Trajectory Command is an important method to reduce vibration in flexible beam. This paper presents a very simple command control shaping which eliminates multiple mode residual vibration in a flexible beam combined parallel fuzzy controller. The effectiveness of proposed scheme is demonstrated through computer simulation.

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Discrete-time Sliding Mode Control with Input Shaping for flexible systems

  • Woo, Lim-Hyun;Choo, Chung-Chung
    • 제어로봇시스템학회:학술대회논문집
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    • 2001.10a
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    • pp.130.5-130
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    • 2001
  • This paper presents a discrete-time sliding mode control method for linear time-invariant systems with matched uncertainties. In this paper, we suggest a method of adding a command generator using input shaping filter to a discrete-time sliding mode controller. We design the number of steps required to reach the sliding layer and the magnitude of a control input, respectively using the shaping filter. Therefore we can minimize the excitation of the resonance mode and increase the tracking performance of a system. Simulation results are included to show its effectiveness.

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