• Title/Summary/Keyword: Limited-DOF Mechanism

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Optimal Kinematic Design of Planar Parallel Mechanisms: Application to 2RRR-RP Mechanism (평면형 병렬 기구의 기구학적 최적설계: 2RRR-RP기구에 적용)

  • Nam Yun-Joo;Lee Yuk-Hyung;Park Myeong-Kwan
    • Journal of Institute of Control, Robotics and Systems
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    • v.12 no.5
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    • pp.464-472
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    • 2006
  • This paper presents the two degree-of-freedom (DOF) planar parallel mechanism, called the $2{\underline{R}}RR-RP$ manipulator, whose degree-of-freedom is dependent on an additional passive constraining leg connecting the base and the platform. First, the kinematic analysis of the mechanism is performed: the inverse and forward kinematic problems are analytically solved, the workspace is systematically derived, and all of the singular configurations are examined. Then, in order to determine the geometric parameters the optimization of the mechanism is performed considering its dexterity, stiffness, and space utilization. Finally, the kinematic performances of the optimized mechanism are evaluated through the comparison study to the conventional 5-bar parallel manipulator.

Kinematic Analysis and Optimal Design of 2RPR-RP Parallel Manipulator (2RPR-RP 병렬 기구의 기구학 해석 및 최적설계)

  • Nam, Yun-Joo;Lee, Yuk-Hyung;Park, Myeong-Kwan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.11 s.242
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    • pp.1509-1517
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    • 2005
  • This paper presents the two degree-of-freedom(DOF) planar parallel mechanism called 2R$\underline{P}$R-RP manipulator, whose degree-of freedom is dependent on a passive constraining leg connecting the base and the platform. First, the kinematic analysis of the mechanism is performed analytically: the inverse and forward kinematic problems are solved in the closed font the practical workspace is systematically derived, and all of the singular configurations are examined. Then, in order to determine the geometric parameters and the operating limits of the actuators, the optimization of the mechanism is performed considering its dexterity and stiffness. Finally, the kinematic performances of the optimized mechanism are evaluated through comparing to the 5-bar parallel manipulator.

Development of Modeling and control Methods for Multi-DOF dielectric polymer actuator

  • Jung, M.Y.;Jung, K.M.;Koo, J.C.;Choi, H.R.;Nam, J.D.;Lee, Y.K.
    • 제어로봇시스템학회:학술대회논문집
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    • 2004.08a
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    • pp.1225-1228
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    • 2004
  • Principles and mechanism of energy transduction of dielectric polymer materials are well known from the various smart material related publications. However their introduction to industrial actuator applications is limited mainly due to difficulties guarantee controllability and reliability. Most of the previous publications have elaborates energy transduction physics of chunk of polymer while development of construction methods for feasible actuators made of the material is rarely proposed. In the present article, a conceptual design of multi-DOF linear polymer actuator construction that is to be controllable with moderate level of control work os introduced. In addition, numerical models that are developed with a unified energy based approach are presented not only for basic working mechanism analysis of the polymetric soft actuator but for providing analytical foundation to expend the concept toward design of multi-DOF actuator controls.

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Kinematics and Optimization of 2-DOF Parallel Manipulator with Revolute Actuators and a Passive Leg

  • Nam Yun-Joo;Park Myeong-Kwan
    • Journal of Mechanical Science and Technology
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    • v.20 no.6
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    • pp.828-839
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    • 2006
  • In this paper, a 2-DOF planar parallel manipulator with two revolute actuators and one passive constraining leg. The kinematic analysis of the mechanism is analytically performed : the inverse and forward kinematics problems are solved in closed forms, the workspace is derived systematically, and the three kinds of singular configurations are round. The optimal design to determine the geometric parameters and the operating limits of the actuated legs is performed considering the kinematic manipulability and workspace size. These results of the paper show the effectiveness of the presented manipulator.

Identification of eighteen flutter derivatives of an airfoil and a bridge deck

  • Chowdhury, Arindam Gan;Sarkar, Partha P.
    • Wind and Structures
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    • v.7 no.3
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    • pp.187-202
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    • 2004
  • Wind tunnel experiments are often performed for the identification of aeroelastic parameters known as flutter derivatives that are necessary for the prediction of flutter instability for flexible structures. Experimental determination of all the eighteen flutter derivatives for a section model facilitates complete understanding of the physical mechanism of flutter. However, work in the field of identifying all the eighteen flutter derivatives using section models with all three degree-of-freedom (DOF) has been limited. In the current paper, all eighteen flutter derivatives for a streamlined bridge deck and an airfoil section model were identified by using a new system identification technique, namely, Iterative Least Squares (ILS) approach. Flutter derivatives of the current bridge and the Tsurumi bridge are compared. Flutter derivatives related to the lateral DOF have been emphasized. Pseudo-steady theory for predicting some of the flutter derivatives is verified by comparing with experimental data. The three-DOF suspension system and the electromagnetic system for providing the initial conditions for free-vibration of the section model are also discussed.

3DOF Endoscope with Spring Backbone and Wires (스프링 백본과 와이어를 이용한 3자유도 내시경)

  • Choi, Dong-Geol;Yi, Byung-Ju
    • The Journal of Korea Robotics Society
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    • v.3 no.3
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    • pp.203-211
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    • 2008
  • This work proposes structure of spring backbone micro endoscope. For effective surgery in narrow and limited space, many manipulators are developing that different to existed structure. This device can move like elephant nose or snake unlike the existing robots. For this motion, a mechanism that uses spring backbone and wires has been developed. The new type endoscope that has Z axis motion for spring structure, therefore it has 3 degree of freedom, two rotations and one linear motion. And new kinematics for backbone structure is proposed using simple geographic analysis. The Jacobian and stiffness modeling are also derived. Exact actuator sizing is determined using stiffness model. Finally, the proposed kinematics are verified by simulation and experiments.

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Development of 6 DOF Positioning Manipulator Using Closed Loop Structure and Its Kinematic Analysis (폐루프 구조를 가지는 6 자유도 머니퓰레이터의 개발 및 기구학적 해석)

  • 김경찬;우춘규;김수현;곽윤근
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.1
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    • pp.60-68
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    • 1998
  • Parallel link manipulators have an ability of more precise positioning than serial open-loop manipulators. However. general parallel link manipulators have been restricted to the real applications since they have limited workspace due to interference among actuators. In this study, we suggest a closed-loop manipulator with 6 degrees-of-freedom and with enlarged workspace. It consists of two parts for minimizing the interference among actuators. One part is lower structure with planar 3 degrees-of-freedom and the other is upper one with spatial 3 degrees-of-freedom. Forward kinematics and inverse kinematics are solved, research about singularity points are carried out and workspace is evaluated. The comparison of workspace between Stewart platform, which is the typical parallel link manipulator, and the suggested manipulator shows that the workspace of the latter is wider than that of the former. Especially, simulation results also show that the suggested manipulator is more suitable when there needs rotation in the end-effector.

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