• Title, Summary, Keyword: Three Degree of Freedom

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A study on the control-in-the-small characteristics of a planar parallel mechanism (평면형 병렬 메카니즘의 국소적 제어 특성에 관한 연구)

  • Kim, Whee-kuk;Cho, Whang;Kim, Jae-Seoub
    • Journal of Institute of Control, Robotics and Systems
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    • v.4 no.3
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    • pp.360-371
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    • 1998
  • In this paper, output precision characteristics of a planar 6 degree-of-freedom parallel mechanisms are investigated, where the 6 degree-of-freedom mechanism is formed by adding an additional link along with an actuated joint in each serial subchain of the planar 3 degree-of-freedom parallel mechanism. Kinematic analysis for the parallel mechanism is performed, and its first-order kinematic characteristics are examined via kinematic isotropic index, maximum and minimum input-output velocity transmission ratios of the mechanisms. Based on this analysis, two types of planar 6 degrees-of-freedom parallel manipulators are selected. Then, dynamic characteristics of the two selected planar 6 degree-of-freedom parallel mechanisms, via Frobenius norms of inertia matrix and power modeling array, are investigated to compare the magnitudes of required control efforts of both three large actuators and three small actuators when the link lengths of three additional links are changed. It can be concluded from the analysis results that each of these two planar 6 degrees-of-freedom parallel mechanisms has an excellent control-in-the-small characteristics and therefore, it can be very effectively employed as a high-precision macro-micro manipulator when both its link lengths and locations of small and large actuators are properly chosen.

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Kinematic analysis of a 6-degree-of-freedom micro-positioning parallel manipulator (6자유도를 갖는 정밀 위치제어용 병렬 매니퓰레이터의 기구학 해석)

  • 박주연;심재홍;권동수
    • 제어로봇시스템학회:학술대회논문집
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    • pp.213-216
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    • 1996
  • This paper studies a class of in-parallel manipulators with special geometry where the forward displacement analysis problem can be solved easier than the fully parallel manipulators. Three horizontal links of this mechanism provide 3DOFs(Degrees of Freedom), which are one degree of orientational freedom and two degrees of translatory freedom. Three vertical links of this mechanism provide 3DOFs, which are two degrees of orientational freedom and one degree of translatory freedom. The main advantages of this manipulator, compared with the Stewart platform type, are the capability to produce pure rotation and to predict the motion of the moving platform easily. Since this manipulator has simple kinematic characteristics compared with the Stewart platform, controlling in real-time is possible due to less computational burden. The purpose of this investigation is to develope an analytical method and systematic method to analyze the basic kinematics of the manipulator. The basic kinematic equations of the manipulator are derived and simulation is carried out to show the performance of the mechanism.

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Study on Some Problems in the Measurement and Estimation of 6 Degree of Freedom Head Vibration in Very Low Frequency Range (극 저주파 범위에서의 인체 머리부 6자유도 진동 측정 및 추정시의 문제점에 대한 연구)

  • 이정훈;고홍석;김광준;장한기
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.621-626
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    • 2002
  • Two problems in the measurement of 6-DOF head vibration in very low frequency range were investigated in this study. One is how much error was involved in the estimation of three rotational and three translational motion at any specified point from measured 6 translational accelerations. The other is quantitative and qualitative influence of gravity on DC and AC component of the estimated accelerations in 6 degree of freedom, which were derived from pick-ups fixed on a helmet. In the study the effect of nonlinear terms on the estimation of 6 degree of freedom accelerations was negligible but gravity effect must be considered carefully.

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A Three-Degree-of-Freedom Anthropomorphic Oculomotor Simulator

  • Bang Young-Bong;Paik Jamie K.;Shin Bu-Hyun;Lee Choong-Kil
    • International Journal of Control, Automation, and Systems
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    • v.4 no.2
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    • pp.227-235
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    • 2006
  • For a sophisticated humanoid that explores and learns its environment and interacts with humans, anthropomorphic physical behavior is much desired. The human vision system orients each eye with three-degree-of-freedom (3-DOF) in the directions of horizontal, vertical and torsional axes. Thus, in order to accurately replicate human vision system, it is imperative to have a simulator with 3-DOF end-effector. We present a 3-DOF anthropomorphic oculomotor system that reproduces realistic human eye movements for human-sized humanoid applications. The parallel link architecture of the oculomotor system is sized and designed to match the performance capabilities of the human vision. In this paper, a biologically-inspired mechanical design and the structural kinematics of the prototype are described in detail. The motility of the prototype in each axis of rotation was replicated through computer simulation, while performance tests comparable to human eye movements were recorded.

Design of a Vibration Absorber for an Elastically Suspended Rigid Body (단일 진동체의 진동 흡진기 설계 기법)

  • Kim, Dong-Wook;Choi, Yong-Je
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.190-197
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    • 2002
  • A new design methodology is presented for the multi-degree-of-freedom vibration absorber for an elastically suspended rigid body with planes of symmetry in general motion. Unlike the common single degree-of-freedom vibration absorber, the presented methodology makes use of both linear and rotational properties of the absorber. It is suggested that an absorber is designed separately for the in-plane and out-of-plane vibration modes and thereby combined the two cases for a six-degree-of-freedom absorber. The nine possible design methods are suggested for the six-degree-of-freedom absorber when an elastically suspended rigid body has one, two, or three planes of symmetry.

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A Study on the Amelioration of Volumetric Efficiency by Variable Induction System in a Diesel Engine (가변 흡기시스템에 의한 디젤기관의 체적효율 향상에 관한 연구)

  • Kang, H.Y.
    • Journal of Power System Engineering
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    • v.10 no.1
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    • pp.12-18
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    • 2006
  • A three-degree of freedom model of intake system was contrived and investigated in various ways for the purpose of the amelioration of the volumetric efficiency in a low and transient engine speed for a multi cylinder diesel engine. The basic concept beyond this model started from the theory that each degree of freedom model has volumetric efficiency peak as many as its number of the degree of freedom. The volumetric efficiency affects significantly to the engine performance; torque characteristics, fuel economy and emission level. For commercial vehicles and stationary engines, the engine is designed so as to produce their best performance near the normal engine speeds, thus the low engine speed area has a tendency of poor volumetric efficiency. The aim of this study was highlighted on the amelioration of volumetric efficiency of low engine speed area in a multi cylinder diesel engine matched with an additional Helmholtz resonator. By the use of VIS(variable induction system) volumetric efficiency at low engine speed range was significantly improved. The availability of control by combination of VIS and CIS(conventional induction system) will be proposed as a variable induction system that would be an appropriate model for amelioration of the volumetric efficiency at low engine speed.

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A Didactical Analysis on the Degree of Freedom (자유도의 교수학적 분석)

  • Kim, Changil;Jeon, Youngju
    • Journal of the Korean School Mathematics Society
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    • v.23 no.3
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    • pp.239-257
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    • 2020
  • This study analyzes the degree of freedom with three aspects: as academic knowledge, in the curriculum focused on textbooks, and students' understanding of the degree of freedom. The results provide five critical points. First, we need discussions on whether to include the degree of freedom in the curriculum. Second, we need to reconsider the current way textbooks are described. Third, there should be a didactical analysis to advance students' understanding of the concept of the degree of freedom. Fourth, there are limitations in learning the concept of the degree of freedom in the current textbook learning environment. Fifth, a didactical check of sampling distribution such as sample mean, sample variance, and sample standard deviation is required. The implications were drawn that the emphasis on statistical reasoning education in the curriculum and careful consideration of introducing the t-distribution curriculum was required.

Improve of Efficiency of Multi D.O.F Spherical Motor Through the Reduction of Eddy Current Loss (다자유도 구형 구동 모터의 와전류 손실 저감을 통한 효율 향상 연구)

  • Hong, Kyung-Pyo;Kim, Yong;Jang, Ik-Sang;Lee, Ho-Joon;Kang, Dong-Woo;Won, Sung-Hong;Lee, Ju
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.61 no.1
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    • pp.50-56
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    • 2012
  • The Multi D.O.F spherical motor can drive rotating as well as tilting three degree of freedom with one motor. Existing three degree of freedom to drive with three motors that are connected by gears and belts, that will be too large size and big loss at gears and belts. So Reducing system size and improving efficient is using the Multi D.O.F spherical motor in three degree of freedom systems. For this reason, efficiency of Multi D.O.F spherical motor is one of the important performance indiccators. In this paper presented that how to improve the efficiency of the Multi D.O.F spherical motor. The fist of method is using the stator iron core's material with high permeability and resistivity for reducing the eddy current loss. However, it was the disadvatages of motor-making and economic. So author propose the resonable method of reducing the eddy current loss in the stator iron core. That is using the rotor with double-air gap.

Manufacturing 2DOF Inflatable Joint Actuator by Pneumatic Control (공압제어를 통한 2DOF 팽창식 관절 액추에이터 제작)

  • Oh, Namsoo;Lee, Haneol;Rodrigue, Hugo
    • The Journal of Korea Robotics Society
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    • v.13 no.2
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    • pp.92-96
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    • 2018
  • In this paper, a soft robotic arm which can prevent impact injury during human-robot interaction is introduced. Two degrees of freedom joint are required to realize free movement of the robotic arm. A robotic joint concept with a single degree of freedom is presented using simple inflatable elements, and then extended to form a robotic joint with two degrees of freedom joint using similar manufacturing methods. The robotic joint with a single degree of freedom has a joint angle of $0^{\circ}$ bending angle when both chamber are inflated at equal pressures and maximum bending angles of $28.4^{\circ}$ and $27.1^{\circ}$ when a single chamber if inflated. The robotic joint with two degrees of freedom also has a bending angle of $0^{\circ}$ in both direction when all three chambers are inflated at equal pressures. When either one or two chambers were pressurized, the robotic joint performed bending towards the uninflated chambers.

Efficient Analysis Models for Vertical Vibration of Space Framed Structures (3차원 골조구조물의 효율적인 연직진동해석)

  • 안상경;홍성일;이동근
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.78-85
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    • 1996
  • The effect of vertical vibration of a beam is significantly influenced by higher modes of vibration. Therefore, a beam can be modeled using several elements must De used to represent a vibrating beam. As a result, analysis of a space framed structure for vertical vibration requires increase number of elements leading to more complicated model with many degree of freedom which requires large amount of computing resources for dynamic analysis. An efficient analysis method for vertical vibration of space framed structures are proposed in this paper which is presented in three method. The first method is to determine minimum nodes that shall be used to obtain dynamic response with the vertical vibration. Secondly, matrix condensation methods are introduced to reduce the computation efforts used to perform dynamic analysis and the selection of primary degree-of-freedom is proposed. The third method is of using the mass participation factor for the selection of primary degree-of-freedom.

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