• Title/Summary/Keyword: flexible manipulator

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Model-based Reference Trajectory Generation for Tip-based Learning Controller

  • Rhim Sungsoo;Lee Soon-Geul;Lim Tae Gyoon
    • Journal of Mechanical Science and Technology
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    • v.19 no.spc1
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    • pp.357-363
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    • 2005
  • The non-minimum phase characteristic of a flexible manipulator makes tracking control of its tip difficult. The level of the tip tracking performance of a flexible manipulator is significantly affected by the characteristics of the tip reference trajectory as well as the characteristics of the flexible manipulator system. This paper addresses the question of how to best specify a reference trajectory for the tip of a flexible manipulator to follow in order to achieve the objectives of reducing : tip tracking error, residual tip vibration, and the required actuation effort at the manipulator joint. A novel method of tip-based learning controller for the flexible manipulator system is proposed in the paper, where a model of the flexible manipulator system with a command shaping filter is used to generate a smooth and realizable tip reference trajectory for a tip-based learning controller.

Nonlinear Coupling Factor in Dynamic Model of Flexible Manipulator (유연 매니퓰레이터 동역학 모델링의 비선형 커플링 요소)

  • Lee Jin-Ho;Rhim Sung-Soo;Lee Soon-Geul
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.10a
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    • pp.404-408
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    • 2005
  • Having flexibility in a manipulator will degrade trajectory tracking control and manipulator tip positioning. In practice, however, constraints imposed by various operating requirements, will render the presence of such flexibility unavoidable. The dynamic analysis of the flexible manipulator is essential in designing proper control systems. A flexible manipulator consists of infinite number of elastic modes and the modes are usually coupled to each other. For the practicality, however, it is usually assumed that the flexible system consists of finite number of elastic modes and the modes are decoupled. These assumptions result in a linear and decoupled mathematical model of the flexible manipulator and simplify the analysis of the dynamic behavior and the design of the control system. The decoupling and linearization of the flexible link, however, has been assumed without in depth analysis. This paper focuses on the analysis of the significance of the non-linear coupling factors.

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Vibration Control of a Single-Link Flexible Manipulator Using Reaction Moment Estimator (반력모멘트 추정기를 이용한 단일 링크 유연 조작기의 진동제어)

  • Shin, Hocheol;Han, Sangsoo;Kim, Seungho
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.2 s.95
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    • pp.169-175
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    • 2005
  • In this paper, a novel vibration control scheme for a single-link flexible manipulator system without using a vibration feedback sensor is proposed. In order to achieve the vibration information of the flexible link, a reaction moment estimator based on the dynamic characteristics of the flexible manipulator is proposed. While the manipulator is maneuvering the reaction moment is reciprocally acting on the flexible link and the hub inertia due to the vibration of the link. A sliding mode controller based on the equivalent rigid body dynamics corresponding to the proposed flexible manipulator is then augmented with the reaction moment estimator to realize a decentralized control system. The reaction moment estimator is implemented via the first order low pass filter. The performance of the proposed control scheme is verified by computer simulation and experiment.

Dynamic characterisation of a two-link flexible manipulator: theory and experiments

  • Khairudin, M.;Mohamed, Z.;Husain, A.R.;Mamat, R.
    • Advances in robotics research
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    • v.1 no.1
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    • pp.61-79
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    • 2014
  • This paper presents theoretical and experimental investigations into the dynamic modelling and characterisation of a two-link flexible manipulator incorporating payload. A planar two-link flexible manipulator that moves in a horizontal plane is considered. A dynamic model of the system is developed using a combined Euler-Lagrange and assumed mode methods, and simulated using Matlab. Experiments are performed on a lab-scaled two-link flexible manipulator for validation of the dynamic model and characterisation of the system. Two system responses namely hub angular position and deflection responses at both links are obtained and analysed in time and frequency domains. The effects of payload on the dynamic characteristics of the flexible manipulator are also studied and discussed. The results show that a close agreement between simulation and experiments is achieved demonstrating an acceptable accuracy of the developed model.

Design of fuzzy logic controller using genetic algorithms for the flexible manipulator (Flexible manipulator를 위한 유전 알고리즘을 이용한 퍼지 제어기 설계)

  • 허남건;이기성
    • 제어로봇시스템학회:학술대회논문집
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    • 1997.10a
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    • pp.1808-1811
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    • 1997
  • A position control algorithm for a flexible manipulato is stuudied. The proposed algorithm is based on a fuzzy theroy with a Steady State Genetic Algorithm(SSGA). The conventional fuzzy methods need expert's knowledges or human experiences. The SSGA, which is one of the optimization algorithms, tunes automatically the input-output membership parameters and fuzzy rules. The computer simulation is presented ot illustrate the approaches. Finally we applied a fuzzy theory with a SSGA to aposition control of a flexible manipulator.

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Design of a Controller for a Flexible Manipulator Using Fuzzy Theory and Genetic Algorithm (피지이론과 유전알고리츰의 합성에 의한 Flexible Manipulator 제어기 설계)

  • Lee, Kee-Seong;Cho, Hyun-Chul
    • Journal of the Korean Institute of Intelligent Systems
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    • v.12 no.1
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    • pp.61-66
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    • 2002
  • A position control algorithm for a flexible manipulator is studied. The proposed algorithm is based on a fuzzy theory with a Steady State Genetic Algorithm(SSGA) and an Adaptive Genetic Algorithms(AGA). The proposed controller for a flexible manipulator have decreased 90.8%, 31.8%, 31.3% in error when compared with a conventional fuzzy controller, fuzzy controller using neural network, fuzzy controller using evolution strategies, respectively when the weight and the velocity of end-point are 0.8k9 and 1m/s, respectively.

H$_\infty$ control of a flexible manipulator using voice coil motor (보이스코일 모터를 이용한 유연한 조작기의 H$_\infty$제어)

  • 박형욱;박노철;박영필;김승호
    • 제어로봇시스템학회:학술대회논문집
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    • 1997.10a
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    • pp.1700-1703
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    • 1997
  • The flexibility of the manipulator inevitably inducess the vibration at the end effector. For the increase in speed and accuracy at the end tip, in this work, position and vibration control of a flexible manipuator with a separate voice coil type actrator for vibration suppression, is studied. The flexible manipulator with a tip mass is modeled an Euler-Bernoulli beam. An H.inf. controller is designed in order to make the controlled system robust against unmodeled higher-order mode vibration of the manipulator, output sensor noise, and etc. Simulations and experiments show that the modeling of the system is valid and that robust vibration control of the flexible manipulator is efficiently achieved.

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An inverse dynamic trajectory planning for the end-point tracking control of a flexible manipulator

  • Kwon, Dong-Soo;Babcock, Scott-M.;Book, Wayne-J.
    • 제어로봇시스템학회:학술대회논문집
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    • 1992.10b
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    • pp.599-606
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    • 1992
  • A manipulator system that needs significantly large workspace volume and high payload capacity has greater link flexibility than typical industrial robots and teleoperators. If link flexibility is significant, position control of the manipulator's end-effector exhibits the nonminimum phase, noncollocated, and flexible structure system control problems. This paper addresses inverse dynamic trajectory planning issues of a flexible manipulator. The inverse dynamic equation of a flexible manipulator was solved in the time domain. By dividing the inverse system equation into the causal part and the anticausal part, the inverse dynamic method calculates the feedforward torque and the trajectories of all state variables that do not excite structural vibrations for a given end-point trajectory. Through simulation and experiment with a single-Unk flexible manipulator, the effectiveness of the inverse dynamic method has been demonstrated.

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A comparative study in input shaping techniques using a flexible manipulator (유연한 조작기를 이용한 입력성형기법의 비교 연구)

  • 심호석;이재원;주해호
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10b
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    • pp.1269-1272
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    • 1996
  • Several input shaping techniques are suggested to reduce the vibration of a flexible manipulator. The theories of typical 4 methods(Singer, Tuttle, Feddema, Zuo) are explained and are tested by the experiment of one link flexible manipulator. Zuo's method is the best of all with respect to its robustness.

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Adaptive control of flexible joint manipulators based on the singular perturbation theory (특이 섭동 이론에 의한 유연성 관절 매니퓰레이터의 적응제어)

  • 김응석;양해원
    • 제어로봇시스템학회:학술대회논문집
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    • 1991.10a
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    • pp.7-11
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    • 1991
  • The adaptive control of flexible joint manipulator is the focus of this paper. The full order flexible joint manipulator dynamic system does not allow the determination of a feedback linearization control as for rigid manipulators. This drawback is overcome by a model order reduction based on a singular perturbation strategy. The full order flexible joint manipulator dynamic model is adopted for derivation of the adaptive control law to damp out the elastic oscillations at the joints. It is shown that the joint position error will converge to zero asymptotically and that other signals remain bounded without precise knowledge of parameters of the manipulator and its joint flexibility.

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