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RISS 인기검색어
- 검색키워드
- 저자 : Habib Esfandiar (검색결과 4 건)
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Complete dynamic modeling and approximate state space equations of the flexible link manipulator
Habib Esfandiar,Saeed Daneshmand 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.9
This work treats the problem of dynamic modeling and state space approximation for robotic manipulators with flexibility. Case studies are planar manipulators with a single flexible link together with clamped-free ends and tip mass conditions. In this paper, complete dynamic modeling of the flexible beam without premature linearization in the formulation of the dynamics equations is developed,whereby this model is capable of reproducing nonlinear dynamic effects, such as the beam stiffening due to the centrifugal and the Coriolis forces induced by rotation of the joints, giving it the capability to predict reliable dynamic behavior. On the other hand, in order to show the joint flexibility effects on the model dynamic behaviors, manipulator with structural and joint flexibility is considered. Thus, a reliable model for flexible beam is then presented. The model is founded on two basic assumptions: inextensibility of the neutral fiber and moderate rotations of the cross sections in order to account for the foreshortening of the beam due to bending. To achieve flexible manipulator control, the standard form of state space equations for a flexible manipulator system (flexible link and actuator) is very important. In this study, finite difference method for discretization of the dynamic equations is used and the state space equations of the flexible link with tip mass considering complete dynamic of the system are obtained. Simulation results indicated substantial improvements on dynamic behavior and it is shown that the joint flexibility has a considerable effect on the dynamic behavior of rotating flexible arm that should not be simply neglected. The effects of tip mass is proved to be increasing the elastic deformations' amplitudes and increasing stability.
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Habib Esfandiar,Habibnejad Korayem 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.9
In this study, the researchers try to examine nonlinear dynamic analysis and determine Dynamic load carrying capacity (DLCC) inflexible manipulators. Manipulator modeling is based on Timoshenko beam theory (TBT) considering the effects of shear and rotationalinertia. To get rid of the risk of shear locking, a new procedure is presented based on mixed finite element formulation. In the methodproposed, shear deformation is free from the risk of shear locking and independent of the number of integration points along the elementaxis. Dynamic modeling of manipulators will be done by taking into account small and large deformation models and using extendedHamilton method. System motion equations are obtained by using nonlinear relationship between displacements-strain and 2nd PiolaKirchoffstress tensor. In addition, a comprehensive formulation will be developed to calculate DLCC of the flexible manipulators during thepath determined considering the constraints end effector accuracy, maximum torque in motors and maximum stress in manipulators. Simulation studies are conducted to evaluate the efficiency of the method proposed taking two-link flexible and fixed base manipulatorsfor linear and circular paths into consideration. Experimental results are also provided to validate the theoretical model. The findingsrepresent the efficiency and appropriate performance of the method proposed.
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Closed loop control of the planar flexible manipulator via Youla-Kucera parameterization
Habib Esfandiar,Saeed Daneshmand 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.11
This work treats the problem of controlling a flexible robotic manipulator. The case study is a planar manipulator with a single flexible arm together with a clamped-free end and a tip lumped mass. To control the angular position of the flexible arm using an actuator, a controller method is developed which is based on Youla-Kucera parameterization. The main challenge in this approach is to obtain a Youla parameter with infinity dimensions. This parameter is approximated by a subspace with finite dimensions which makes the problem tractable. The developed approach exhibit advanced theoretical properties and good numerical convergence. In this paper, two sets of orthogonal bases such as FIR and Laguerre bases are used for system identification. The results of the present case study indicate that the proposed method is very efficient and robust for the time-continuous instances. The characteristics of an optimization problem are finally formulated for larger systems with hundreds of variables and solved with the interior point method.
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Large deformation modeling of flexible manipulators to determine allowable load
Habib Esfandiar,Moharam H. Korayem,Mohammad Haghpanahi 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.62 No.5
This paper focuses on the study of complete dynamic modeling and maximum dynamic load carrying capacity computation of N-flexible links and N-flexible joints mobile manipulator undergoing large deformation. Nonlinear dynamic analysis relies on the Timoshenko theory of beams. In order to model the system completely and precisely, structural and joint flexibility, nonlinear strain-displacement relationship, payload, and non-holonomic constraints will be considered to. A finite element solution method based on mixed method is applied to model the shear deformation. This procedure is considerably more involved than displacement based element and shear deformation can be readily included without inducing the shear locking in the element. Another goal of this paper is to present a computational procedure for determination of the maximum dynamic load of geometrically nonlinear manipulators with structural and joint flexibility. An effective measure named as Moment-Height Stability (MHS) measure is applied to consider the dynamic stability of a wheeled mobile manipulator. Simulations are performed for mobile base manipulator with two flexible links and joints. The results represent that dynamic stability constraint is sensitive when calculating the maximum carrying load. Furthermore, by changing the trajectory of end effector, allowable load also changes. The effect of torsional spring parameter on the joint deformation is investigated in a parametric sensitivity study. The findings show that, by the increase of torsional stiffness, the behavior of system approaches to a system with rigid joints and allowable load of robot is also enhanced. A comparison is also made between the results obtained from small and large deformation models. Fluctuation range in obtained figures for angular displacement of links and end effector path is bigger for large deformation model. Experimental results are also provided to validate the theoretical model and these have good agreement with the simulated results.
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