Structural dynamic analysis of low-mobility parallel manipulators

Abstract

This paper focuses on the study of static and dynamic stiffness (normal modes and natural frequencies) by a method which enables to evaluate the vibration behaviour of low mobility parallel manipulators, i.e., less than 6 degrees-of-freedom. The purpose of this study is to improve the structural behaviour of this type of manipulators under the effect of static and dynamic external loads. As a starting point, we use a previously developed methodology for static rigidity obtaining for the aforementioned manipulators characteristics, using as case study DAEDALUS I parallel robot. The method is applied to a simplified model to analyze the evolution of the static stiffness, the frequencies and normal modes in the whole workspace. The method involves the use of one analytical model, other numerical, based on finite elements and a comparison with an experimental campaign on a prototype. From this study, the results of the natural frequencies trends of the manipulator are represented in tridimensional maps. © Springer Science+Business Media B.V. 2010.