• Title/Summary/Keyword: Kinematic parameters

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Post-buckling responses of functionally graded beams with porosities

  • Akbas, Seref D.
    • Steel and Composite Structures
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    • v.24 no.5
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    • pp.579-589
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    • 2017
  • The objective of this work is to analyze post-buckling of functionally graded (FG) beams with porosity effect under compression load. Material properties of the beam change in the thickness direction according to power-law distributions with different porosity models. It is known that post-buckling problems are geometrically nonlinear problems. In the nonlinear kinematic model of the beam, total Lagrangian finite element model of two dimensional (2-D) continuum is used in conjunction with the Newton-Raphson method. In the study, the effects of material distribution, porosity parameters, compression loads on the post-buckling behavior of FG beams are investigated and discussed with porosity effects. Also, the effects of the different porosity models on the FG beams are investigated in post-buckling case.

Vision-based Kinematic Modeling of a Worm's Posture (시각기반 웜 자세의 기구학적 모형화)

  • Do, Yongtae;Tan, Kok Kiong
    • Journal of Institute of Control, Robotics and Systems
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    • v.21 no.3
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    • pp.250-256
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    • 2015
  • We present a novel method to model the body posture of a worm for vision-based automatic monitoring and analysis. The worm considered in this study is a Caenorhabditis elegans (C. elegans), which is popularly used for research in biological science and engineering. We model the posture by an open chain of a few curved or rigid line segments, in contrast to previously published approaches wherein a large number of small rigid elements are connected for the modeling. Each link segment is represented by only two parameters: an arc angle and an arc length for a curved segment, or an orientation angle and a link length for a straight line segment. Links in the proposed method can be readily related using the Denavit-Hartenberg convention due to similarities to the kinematics of an articulated manipulator. Our method was tested with real worm images, and accurate results were obtained.

Tilted-Ring Modeling of Warped Spiral Galaxies

  • Bae, Hyun-Jin;Chung, Ae-Ree;Jozsa, Gyula I.G.;Kim, Sung-Soo;Yoon, Suk-Jin
    • The Bulletin of The Korean Astronomical Society
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    • v.35 no.2
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    • pp.30.2-30.2
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    • 2010
  • A direct tilted-ring fitting method allows us to investigate kinematic structure of spiral galaxies. By employing the method to high-resolution HI data cubes, we can more easily trace warp characteristics of spiral galaxies than ever. In this contribution, we make use of TiRiFiC to VLA HI data cube of spiral galaxies in Virgo cluster, and present our preliminary yet interesting results. The TiRiFiC (Tilted-Ring-Fitting-Code) is publicly available code that provides 'best-fit' tilted-ring parameters (i.e. position angle and inclination) via chi-square minimization technique. We also discuss possible biases (e.g., resolution dependency) and its effect on our conclusions.

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Analysis on Mobility of Planar Mobile Robots (평면형 모바일 로봇의 모빌리티에 대한 분석)

  • Kim, Wheekuk;Lee, Seung-Eun;Yi, Byung-Ju
    • Journal of Institute of Control, Robotics and Systems
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    • v.8 no.3
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    • pp.243-248
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    • 2002
  • In this paper, mobility of planar mobile robots is discussed. Firstly, simplified joint models for four typical wheels of the mobile robots are described including both rotational and translational friction parameters. Then, based on these joint models and through the inclusion of the additional imaginary joint particularly to the mobile robots which lack geometric generality, mobility analysis of various types of planar mobile robots is performed.

DULEX, A Wearable Hand Rehabilitation Device for Stroke Survivals (뇌졸중 환자를 위한 착용형 손 재활훈련기기, DULEX)

  • Kim, Young-Min;Moon, In-Hyuk
    • Journal of Institute of Control, Robotics and Systems
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    • v.16 no.10
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    • pp.919-926
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    • 2010
  • This paper proposes a wearable hand rehabilitation device, DULEX, for persons with functional paralysis of upper-limbs after stoke. DULEX has three degrees of freedom for rehabilitation exercises for wrist and fingers except the thumb. The main function of DULEX is to extend the range of motions of finger and wrist being contracture. DULEX is designed by using a parallel mechanism, and its parameters such as length and location of links are determined by kinematic analysis. The motion trajectory of the designed DULEX is aligned to human hand to prevent a slip. To reduce total weight of DULEX, artificial air muscles are used for actuating each joint motion. In feedback control, each joint angle is indirectly estimated from the relations of the input air pressure and the output muscle length. Experimental results show that DULEX is feasible in hand rehabilitation for stroke survivals.

Correlations for Predicting Viscosity of Vegetable Oils and Its Derivatives for Compression Ignition Engines

  • No, Soo-Young
    • Journal of ILASS-Korea
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    • v.14 no.3
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    • pp.122-130
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    • 2009
  • Vegetable oil and its derivatives as an alternative diesel fuel have become more attractive recently because of its environmental benefits and the fact that they are made from renewable resources. Viscosity is the most significant property to affect the utilization of vegetable oil and its derivatives in the compression ignition engines. This paper presents the existing correlations for predicting the viscosity of vegetable oil and its derivatives for compression ignition engines. According to the parameter considered in the correlations, the empirical correlations can be divided into six groups: correlations as a function of temperature, of proportion, of composition, of temperature and composition, of temperature and proportion, and of fuel properties. Out of physical properties of fuel, there exist in the literature several parameters for giving the influence on kinematic viscosity such as density, specific gravity, the ratio of iodine value over the saponification value, higher heating value, flash point and pressure. The study for the verification of applicability of existing correlations to non-edible vegetable oil and its derivatives is required.

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Geometric Modeling and Trajectory Control Design for an Excavator Mechanism (굴삭기 작업장치부의 기하학적 동역학 모델링 및 궤적 제어에 관한 연구)

  • Kim, S.H.;Yoo, S.J.;Lee, K.I.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.4 no.2
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    • pp.1-6
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    • 2007
  • During the last few decades, excavation automation has been investigated to protect the operator from the hazardous working environment and to relieve the cost of the skilled operator. Therefore, a number of modelling and controller design methods of the hydraulic excavator are proposed in many literatures to realize the excavation automation. In this article, a geometric approach far the multi-body system modeling is adopted to develop the excavator mechanism model that contains 4 kinematic loops and 12 links. Considering a simple soil mechanism model with a number of uncertain soil parameters, an adaptive trajectory tracking control strategy based on the developed excavator model is proposed. The improved performance of the designed controller over the simple PID controller is validated via the simulation study.

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Study on the Observability of Calibration System with a Constraint Oprerator (구속연산자에 의한 보정 시스템의 관측성에 관한 연구)

  • Lee, Min-Ki;Kim, Tae-Sung;Park, Kun-Woo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.4
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    • pp.647-655
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    • 2003
  • This paper studies the observability of calibration system with a constraint movement by a constraint operator. The calibration system with the constraint movement need only simple sensing device to check whether the constraint movements are completed within an established range. However, it yields the concern about the poor parameter observability due to the constraint movements. This paper uses the QR-decomposition to find the optimal calibration configurations maximizing the linear independence of rows of a observation matrix. The number of identifiable parameters are examined by the rank of the observation matrix, which represents the parameter observability. The method is applied to a parallel typed machining center and the calibration results are presented. These results verify that the calibration system with low-cost indicators and simple planar table is accurate as well as reliable.

An Efficient Calibration Procedure of Arc Welding Robots for Offline Programming Application (아아크 용접용 로보트의 오프라인 프로그램 응용을 위한 효과적 캘리브레이션 방법 연구)

  • Borm, Jin-Hwan
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.1
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    • pp.131-142
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    • 1996
  • Most industrial robots cannot be off-line programmed to carry out a task accurately, unless their kinematic model is suitably corrected through a calibration procedure. However, normal calibration is an expensive and time-consumming precedure due to the highly accurate measurement equipment required and due to the significant amount of data that must be collected. This paper presents a simple and economic procedure to improve the efficiency of robot calibration especially for arc welding application. To simplify the measurement process, an automotic data measurement algorithm as well as a simple measurement device are developed. Also, a calibration algorithm which can automatically identify the independent model parameters to be estimated is presented. To demonstrated the simplicity and the effectiveness of the procedure, experimental studies and computer simulations are performed and their results are discussed.

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Local and Global Isotropy Analysis of Caster Wheeled Omnidirectional Mobile Robot

  • Kim Sung-bok;Moon Byoung-kwon
    • Journal of the Institute of Convergence Signal Processing
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    • v.7 no.1
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    • pp.38-44
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    • 2006
  • The omnidirectional mobility of a mobile robot may lose significance in motion control, unless the isotropy characteristics of the mechanism is maintained well. This paper investigates the local and global isotropy of an omnidirectional mobile robot with three caster wheels. All possible actuations with different number and combination of rotating and steering joints are considered. First, the kinematic model based on velocity decomposition and the algebraic conditions for the local isotropy are obtained. Second, the geometric conditions for the local isotropy are derived and all isotropic configurations are fully identified. Third, the global isotropy index is examined to determine the optimal parameters in terms of actuation set, characteristic length, and steering link length.

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