Kinematic and stiffness analysis of the Orthoglide, a PKM with simple, regular workspace and homogeneous performances

TL;DR

This paper introduces a new method for analyzing the stiffness of the Orthoglide, a Delta-type PKM, and benchmarks its geometric, kinematic, and stiffness performance criteria to demonstrate its regular workspace and uniform performance.

Contribution

A novel stiffness analysis method for overconstrained Delta-type PKMs like the Orthoglide is proposed and its performance is benchmarked against key criteria.

Findings

Orthoglide has a regular Cartesian workspace shape.

It exhibits uniform performances in all directions.

The stiffness and workspace efficiency are validated through benchmarking.

Abstract

The Orthoglide is a Delta-type PKM dedicated to 3-axis rapid machining applications that was originally developed at IRCCyN in 2000-2001 to meet the advantages of both serial 3-axis machines (regular workspace and homogeneous performances) and parallel kinematic architectures (good dynamic performances and stiffness). This machine has three fixed parallel linear joints that are mounted orthogonally. The geometric parameters of the Orthoglide were defined as function of the size of a prescribed cubic Cartesian workspace that is free of singularities and internal collision. The interesting features of the Orthoglide are a regular Cartesian workspace shape, uniform performances in all directions and good compactness. In this paper, a new method is proposed to analyze the stiffness of overconstrained Delta-type manipulators, such as the Orthoglide. The Orthoglide is then benchmarked according to geometric, kinematic and stiffness criteria: workspace to footprint ratio, velocity and force transmission factors, sensitivity to geometric errors, torsional stiffness and translational stiffness.