Stiffness Analysis of Overconstrained Parallel Manipulators

TL;DR

This paper introduces a novel stiffness modeling approach for overconstrained parallel manipulators using a multidimensional lumped-parameter model with FEA-based link stiffness evaluation, enabling accurate analysis even in singular configurations.

Contribution

It presents a new stiffness modeling method that combines FEA and a virtual spring approach for overconstrained manipulators, including singular postures.

Findings

Validated with comparative stiffness analysis of two manipulators

Accurate stiffness evaluation for Orthoglide manipulator

Effective in analyzing singular configurations

Abstract

The paper presents a new stiffness modeling method for overconstrained parallel manipulators with flexible links and compliant actuating joints. It is based on a multidimensional lumped-parameter model that replaces the link flexibility by localized 6-dof virtual springs that describe both translational/rotational compliance and the coupling between them. In contrast to other works, the method involves a FEA-based link stiffness evaluation and employs a new solution strategy of the kinetostatic equations for the unloaded manipulator configuration, which allows computing the stiffness matrix for the overconstrained architectures, including singular manipulator postures. The advantages of the developed technique are confirmed by application examples, which deal with comparative stiffness analysis of two translational parallel manipulators of 3-PUU and 3-PRPaR architectures. Accuracy of the proposed approach was evaluated for a case study, which focuses on stiffness analysis of Orthoglide parallel manipulator.