• Title/Summary/Keyword: Kinematic parameters

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Robust Nonlinear Control of a Mobile Robot

  • Zidani, Ghania;Drid, Said;Chrifi-Alaoui, Larbi;Arar, Djemai;Bussy, Pascal
    • Journal of Electrical Engineering and Technology
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    • v.11 no.4
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    • pp.1012-1019
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    • 2016
  • A robust control intended for a nonholonomic mobile robot is considered to guarantee good tracking a desired trajectory. The main drawbacks of the mobile robot model are the existence of nonholonomic constraints, uncertain system parameters and un-modeled dynamics. in order to overcome these drawbacks, we propose a robust control based on Lyapunov theory associated with sliding-mode control, this solution shows good robustness with respect to parameter variations, measurement errors, noise and guarantees position and velocity tracking. The global asymptotic stability of the overall system is proven theoretically. The simulation results largely confirm the effectiveness of the proposed control.

The Temperature Dependent C-H/V Constitutive Modeling for Magnesium Alloy Sheet (마그네슘 판재를 위한 온도 의존형 C-H/V 구성 모델에 관한 연구)

  • Park, J.H.;Lee, J.K.;Kim, H.Y.
    • Transactions of Materials Processing
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    • v.21 no.4
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    • pp.221-227
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    • 2012
  • The automotive and electronic industries have seriously considered the use of magnesium alloys because of their excellent properties such as strength to weight ratio, EMI shielding capability, etc. However, it is difficult to form magnesium alloys at room temperature because of the mechanical deformation related to twinning. Hence, magnesium alloys are normally formed at elevated temperatures. In this study, a temperature dependent constitutive model, the C-H/V model, for the magnesium alloy AZ31B sheet is proposed. A hardening law based on nonlinear kinematic and H/V(Hollomon/Voce) hardening model is used to properly characterize the Bauschinger effect and the stabilization of the flow stress. Material parameters were determined from a series of uni-axial cyclic experiments(C-T-C) with the temperature ranging between 150 and $250^{\circ}C$. The developed models are fit to experimental data and a comparison is made.

파지면의 마찰을 고려한 개폐식 파지공구 메카니즘의 기구학적 최적 설계합성

  • 김희국;박주영;윤성식;박진석
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1995.04a
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    • pp.525-530
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    • 1995
  • The main objective of this study is to develop a gripper mechanism that can be employed for assembly and removal tasks of a nozzle-dam of steam gererator which is one of the nuclear reactor maintenance process. Brief description of the open-close type gripper mechanism, its postion analysis, and its kinematic amalysis are given. The optimal design of the gripper mechanism with slipping on its two gripping surfaces is considered. As an optimaldesign index, the ratio of the actuator force of prismatic cylinder to gripping load is proposed. Then, based on this index the optimal design synthesis is careied out to identify values of optimal design parameters for the gripper mechanism.

Effects of porosity models on static behavior of size dependent functionally graded beam

  • Hamed, Mostafa A.;Sadoun, Ayman M.;Eltaher, Mohamed A.
    • Structural Engineering and Mechanics
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    • v.71 no.1
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    • pp.89-98
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    • 2019
  • In this study, the mechanical bending behaviors of functionally graded porous nanobeams are investigated. Four types of porosity which are, the classical power porosity function, the symmetric with mid-plane cosine function, bottom surface distribution and top surface distribution are proposed in analysis of nanobeam for the first time. A comparison between four types of porosity are illustrated. The effect of nano-scale is described by the differential nonlocal continuum theory of Eringen by adding the length scale into the constitutive equations as a material parameter comprising information about nanoscopic forces and its interactions. The graded material is designated by a power function through the thickness of nanobeam. The beam is simply-supported and is assumed to be thin, and hence, the kinematic assumptions of Euler-Bernoulli beam theory are held. The mathematical model is solved numerically using the finite element method. Numerical results show effects of porosity type, material graduation, and nanoscale parameters on the static deflection of nanobeam.

NSGT-based acoustical wave dispersion characteristics of thermo-magnetically actuated double-nanobeam systems

  • Ebrahimi, Farzad;Dabbagh, Ali
    • Structural Engineering and Mechanics
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    • v.68 no.6
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    • pp.701-711
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    • 2018
  • Herein, the thermo-magneto-elastic wave dispersion answers of functionally graded (FG) double-nanobeam systems (DNBSs) are surveyed implementing a nonlocal strain gradient theory (NSGT). The kinematic relations are derived employing the classical beam theory. Also, scale influences are covered precisely in the framework of NSGT. Moreover, Mori-Tanaka homogenization model is introduced in order to obtain the effective material properties of FG nanobeams. Meanwhile, effects of external forces such as thermal and Lorentz forces are included in this research. Also, based upon the Hamilton's principle, the Euler-Lagrange equations are developed; afterwards, these equations are incorporated with those of NSGT to reach the nonlocal governing equations of FG-DNBSs. Furthermore, according to an analytical approach, the governing equations are solved to obtain the wave frequencies and phase velocities of FG-DNBSs. At the end, some illustrations are rendered to clarify the influences of a wide range of involved parameters.

New 3D failure analysis of water-filled karst cave beneath deep tunnel

  • Zhang, R.;Yang, X.L.
    • Geomechanics and Engineering
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    • v.18 no.1
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    • pp.1-9
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    • 2019
  • In this study, both 2D and 3D failure shapes of rock mass above the water-filled cavity are put forward when the surrounding rock mass cannot bear the pressure caused by the water-filled cavity. Based on the analytical expressions derived by kinematic approach, the profiles of active and passive failure patterns are plotted. The sensitivity analysis is conducted to explore the influences of different rock parameters on the failure profiles. During the excavation of the deep tunnels above the karst cavity, the water table always changes because of progressive failure of cavity roof. Therefore, it is meaningful to discuss the effects of varying water level on the failure patterns of horizontal rock layers. The changing laws of the scope of the failure pattern obtained in this work show good consistency with the fact, which could be used to provide a guide in engineering.

Effect of thickness stretching and multi-field loading on the results of sandwich piezoelectric/piezomagnetic MEMS

  • Xiaoping Zou;Gongxing Yan;Wangming Wu;Wenjie Yang;Weiwei Shi;Yuhusun Sun
    • Steel and Composite Structures
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    • v.46 no.4
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    • pp.485-495
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    • 2023
  • Bending static and stress investigation of a microplate of piezoelectric/piezomagnetic material subjected to combined multifield loading. Shear deformable as well as thickness stretched model is used for derivation of the kinematic relations. Multi field governing equations are derived analytically through principle of virtual work. the results are analytically obtained analytically including magnetic/electric potentials, displacement and stress components with variation in multifield loading parameters.

Nonlinear finite element vibration analysis of functionally graded nanocomposite spherical shells reinforced with graphene platelets

  • Xiaojun Wu
    • Advances in nano research
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    • v.15 no.2
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    • pp.141-153
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    • 2023
  • The main objective of this paper is to develop the finite element study on the nonlinear free vibration of functionally graded nanocomposite spherical shells reinforced with graphene platelets under the first-order shear deformation shell theory and von Kármán nonlinear kinematic relations. The governing equations are presented by introducing the full asymmetric nonlinear strain-displacement relations followed by the constitutive relations and energy functional. The extended Halpin-Tsai model is utilized to specify the overall Young's modulus of the nanocomposite. Then, the finite element formulation is derived and the quadrilateral 8-node shell element is implemented for finite element discretization. The nonlinear sets of dynamic equations are solved by the use of the harmonic balance technique and iterative method to find the nonlinear frequency response. Several numerical examples are represented to highlight the impact of involved factors on the large-amplitude vibration responses of nanocomposite spherical shells. One of the main findings is that for some geometrical and material parameters, the fundamental vibrational mode shape is asymmetric and the axisymmetric formulation cannot be appropriately employed to model the nonlinear dynamic behavior of nanocomposite spherical shells.

Dynamic model of hinge deflection in fluid flow (유동 내 굽힘이 발생하는 힌지의 역학 모델)

  • Minho Song;Janggon Yoo;Daegyoum Kim
    • Journal of the Korean Society of Visualization
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    • v.21 no.1
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    • pp.40-46
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    • 2023
  • For application to drag-based propulsion system, the dynamics of a segmented structure with multiple hinges undergoing oscillatory motion are investigated. The side flaps are connected to a centre rod with elastic plates acting as hinges. The hinges bend to only one direction so that the structure behave asymmetrically between the power stroke and the recovery stroke. An analytical model is proposed, which estimates the asymmetric deformation of the segmented structure coupled with hinges. Using the proposed model, the effects of key geometric and kinematic parameters on the dynamics of the structure are analyzed.

The Comparative Analysis of Wearing Roller Shoes and Jogging Shoes on Kinematic Characteristics in the Lower Extremity during Walking (롤러 신발과 조깅 신발 착용 후 보행 시 하지 분절의 운동학적 특성 비교 분석)

  • Jang, Jae-Ik;Chae, Woen-Sik;Kang, Nyeon-Ju;Yoon, Chang-Jin
    • Korean Journal of Applied Biomechanics
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    • v.19 no.2
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    • pp.399-406
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    • 2009
  • The purpose of this study was to compare the effect of wearing roller shoes and jogging shoes on kinematic characteristics in lower extremity during walking. Eight male middle school students(age: $15.0{\pm}0.0^{\circ}$ yrs, height $175.9{\pm}6.6cm$, weight: $616.3{\pm}84.9$ N) who have no musculoskeletal disorder were recruited as the subjects. Temporal parameters, step length, stride length, center of mass, velocity of CM, angle of segment, angular velocity and range of motion were determined for each trial. For each dependent variable, paired t-test was performed to test if significant difference existed between shoe conditions(p < .05). The results showed that stride length and velocity of CM in wearing roller shoes were significantly less than those found in wearing jogging shoes. These indicated that walking patterns may be changed by different shoe conditions and unstable braking condition because of wheel. Angle of ankle joint at LHC1 and LHC2 in wearing roller shoes was greater than the corresponding value for wearing jogging shoes. It seems that the ankle joints are locked in an awkward fashion at the heel contact to compensate for imbalance. Otherwise, dorsi flexion was not produced at the heel contact point in wearing roller shoes.