Dynamic finite-element analysis of a planar high-speed, high-precision parallel manipulator with flexible links

Piras, G.; Cleghorn, W.L.; Mills, James K.

doi:10.1016/j.mechmachtheory.2004.12.007

Cited by 187 publications

(100 citation statements)

References 18 publications

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“…A simplified FEM based on the CMS is used to deal with the dynamic modeling problem of 6-RPR spatial parallel manipulators by modeling the limbs using spatial beam elements [17]. Piras et al [18] established an elastodynamic model of a 3-PRR flexible-link planar parallel platform in similar manner, including the mapping of the first-order natural frequency with respect to the robot configuration. On the assumption that the deformations of the intermediate links are small relative to the length of the links, Zhang et al [19] presented a structural dynamic model for the 3-PRR flexible parallel manipulator using the CMS.…”

Section: Advances In Mechanical Engineeringmentioning

confidence: 99%

Rapid Evaluation for Position-Dependent Dynamics of a 3-DOF PKM Module

Luo

Wang

Zhang

et al. 2014

Advances in Mechanical Engineering

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Based on the substructure synthesis and modal reduction technique, a computationally efficient elastodynamic model for a fully flexible 3-RPS parallel kinematic machine (PKM) tool is proposed, in which the frequency response function (FRF) at the end of the tool can be obtained at any given position throughout its workspace. In the proposed elastodynamic model, the whole system is divided into a moving platform subsystem and three identical RPS limb subsystems, in which all joint compliances are included. The spherical joint and the revolute joint are treated as lumped virtual springs with equal stiffness; the platform is treated as a rigid body and the RPS limbs are modelled with modal reduction techniques. With the compatibility conditions at interfaces between the limbs and the platform, an analytical system governing differential equation is derived. Based on the derived model, the position-dependent dynamic characteristics such as natural frequencies, mode shapes, and FRFs of the 3-RPS PKM are simulated. The simulation results indicate that the distributions of natural frequencies throughout the workspace are strongly dependant on mechanism's configurations and demonstrate an axial-symmetric tendency. The following finite element analysis and modal tests both validate the analytical results of natural frequencies, mode shapes, and the FRFs.

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Section: Advances In Mechanical Engineeringmentioning

confidence: 99%

Rapid Evaluation for Position-Dependent Dynamics of a 3-DOF PKM Module

Luo

Wang

Zhang

et al. 2014

Advances in Mechanical Engineering

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“…The term describes all other effects (e.g., friction of the actuators). For our robot, we decided to neglect Coriolis torques and damping torques due to the relatively slow movements used in arm therapy and their small influence on the dynamics of a robot [20][21]. Therefore, we get a simplified equation of motion out of Equation (6): where G r (q) = the gravitation of the exoskeleton.…”

Section: Inverse Dynamic Robot Modelmentioning

confidence: 99%

Estimating the patient�s contribution during robot-assisted therapy

Guidali¹,

Keller²,

Klamroth-Marganska³

et al. 2013

JRRD

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Abstract-Robot-assisted therapy has become increasingly common in neurorehabilitation. Sophisticated controllers have been developed for robots to assist and cooperate with the patient. It is difficult for the patient to judge to what extent the robot contributes to the execution of a movement. Therefore, methods to comprehensively quantify the patient's contribution and provide feedback are of key importance. We developed a method comprehensively to estimate the patient's contribution by combining kinematic measures and the motor assistance applied. Inverse dynamic models of the robot and the passive human arm calculate the required torques to move the robot and the arm and build, together with the recorded motor torque, a metric (in percentage) that represents the patient's contribution to the movement. To evaluate the developed metric, 12 nondisabled subjects and 7 patients with neurological problems simulated instructed movement contributions. The results are compared with a common performance metric. The estimation shows very satisfying results for both groups, even though the arm model used was strongly simplified. Displaying this metric to patients during therapy can potentially motivate them to actively participate in the training.

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“…degrees of freedom (DOFs). However, the choice of which joint variables to 1 In this paper, R and P denote a revolute and prismatic joint, respectively, whereas U denotes a universal joint. …”

Section: Kinematic Equationsmentioning

confidence: 99%

“…In the literature, the methods of calculating stiffness can be classified as follows: a) finite element analysis (FEA) b) matrix structural analysis (MSA) and c) the virtual joint method (VJM). a) The FEA method, extensively used in structural mechanics, is reliable and accurate as the numerical model can duplicate the entire mechanism faithfully [1,2]. Its accuracy is limited by the intrinsic parameters of the discretization mesh.…”

Section: Introductionmentioning

confidence: 99%

Cartesian Stiffness Matrix Mapping of a Translational Parallel Mechanism with Elastic Joints

Ruggiu

2012

International Journal of Advanced Robotic Systems

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This paper is devoted to calculating the Cartesian stiffness matrix of a translational parallel manipulator with elastic joints. The calculation takes into account the contribution of the Jacobian variation because of the change of manipulator configuration due to the elasticity and it covers the entire theoretical workspace of the manipulator. Three kineto-static adimensional indices are proposed to measure the response of the manipulator in terms of stiffness.

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Dynamic finite-element analysis of a planar high-speed, high-precision parallel manipulator with flexible links

Cited by 187 publications

References 18 publications

Rapid Evaluation for Position-Dependent Dynamics of a 3-DOF PKM Module

Rapid Evaluation for Position-Dependent Dynamics of a 3-DOF PKM Module

Estimating the patient�s contribution during robot-assisted therapy

Cartesian Stiffness Matrix Mapping of a Translational Parallel Mechanism with Elastic Joints

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