scholarly journals On the Stiffness Analysis and Elastodynamics of Parallel Kinematic Machines

10.5772/31891 ◽  
2012 ◽  
Author(s):  
Alessandro Cammarata
Keyword(s):  
Stiffness Analysis ◽  
Parallel Kinematic Machines ◽  
Parallel Kinematic

scholarly journals Conceptual design and comparative stiffness analysis of an Exechon-like parallel kinematic machine with lockable spherical joints

2017 ◽  
Vol 14 (4) ◽  
pp. 172988141772413
Author(s):  
Teng-fei Tang ◽  
Jun Zhang
Keyword(s):  
Conceptual Design ◽  
Prediction Accuracy ◽  
Parallel Kinematic Machine ◽  
Stiffness Analysis ◽  
Parallel Kinematic Machines ◽  
Stiffness Model ◽  
Dynamic Analyses ◽  
Parallel Kinematic ◽  
Kinetostatic Model ◽  
Limb Structure

This article proposes two types of lockable spherical joints which can perform three different motion patters by locking or unlocking corresponding rotational axes. Based on the proposed lockable spherical joints, a general reconfigurable limb structure with two passive joints is designed with which the conceptual designs of two types of Exechon-like parallel kinematic machines are completed. To evaluate the stiffness of the proposed Exechon-like parallel kinematic machines, an expanded kinetostatic model is established by including the compliances of all joints and limb structures. The prediction accuracy of the expanded stiffness model is validated by numerical simulations. The comparative stiffness analyses prove that the Exe-Variant parallel kinematic machine claims competitive rigidity performance to the Exechon parallel kinematic machine. The present work can provide useful information for further investigations on structural enhancement, rigidity improvement, and dynamic analyses of other Exechon-like parallel kinematic machines.

Error Sensitivity Analysis for Optimal Calibration of Parallel Kinematic Machines

2002 ◽  
Author(s):  
Fengfeng Xi ◽  
Marcel Verner ◽  
Chris Mechefske
Keyword(s):  
Sensitivity Analysis ◽  
Error Model ◽  
Condition Numbers ◽  
Geometric Errors ◽  
Error Sensitivity ◽  
Parallel Kinematic Machines ◽  
Parallel Kinematic ◽  
Error Sensitivity Analysis ◽  
Jacobian Inverse ◽  
Optimal Calibration

In this paper, error sensitivity analysis is discussed for the purpose of optimal calibration of parallel kinematic machines (PKMs). The idea is to find a less error sensitive area in the workspace for calibration. To do so, an error model is developed that takes into consideration all the geometric errors due to imprecision in manufacturing and assembly. Based on this error model, it is shown that the error mapping from the geometric errors to the pose error of the PKM depends on the Jacobian inverse. The Jacobian inverse would introduce spurious errors that would affect the calibration results, if used without proper care. Hence, it is suggested to select the areas in the workspace with smaller condition numbers for calibration. A case study is presented to illustrate the proposed method.

Stiffness Analysis of a Tripod With a Passive Link

2005 ◽  
Author(s):  
Z. M. Bi ◽  
S. Y. T. Lang ◽  
D. Zhang
Keyword(s):  
Constrained Motion ◽  
Motion Platform ◽  
Stiffness Analysis ◽  
Stiffness Model ◽  
Parallel Kinematic Mechanism ◽  
Parallel Kinematic ◽  
Linear Actuators ◽  
Main Components ◽  
Kinematic Mechanism

The system stiffness of a tripod parallel kinematic mechanism (PKM) with 3-DOF is investigated in this paper. The tripod PKM has rotations of a motion platform about the x and y axes and translation along the z axis. The motion on the other axes is constrained by a passive link. The stiffness model considers the compliances of three main components: the fixed-length links, the passive link, and the linear actuators. The modeling procedure for the kinetostatic stiffness model is introduced. A case study is provided to demonstrate evaluation of the stiffness of our prototype tripod machine. The developed model differs from the others in the sense that the stiffness on the motion axes is determined by both the active links and the passive link; but the stiffness on the constrained motion axes depends merely on the passive link.

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