Experimental Analysis of Type II Singularities and Assembly Change Points in a 3UPS+RPU Parallel Robot

Fuente: arXiv
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Main Authors: Pulloquinga, Jose L., Mata, Vicente, Valera, Angel, Zamora-Ortiz, Pau, Diaz-Rodriguez, Miguel, Zambrano, Ivan
Format: Preprint
Published: 2024
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author Pulloquinga, Jose L.
Mata, Vicente
Valera, Angel
Zamora-Ortiz, Pau
Diaz-Rodriguez, Miguel
Zambrano, Ivan
author_facet Pulloquinga, Jose L.
Mata, Vicente
Valera, Angel
Zamora-Ortiz, Pau
Diaz-Rodriguez, Miguel
Zambrano, Ivan
contents Parallel robots (PRs) have singular configurations where the robot gains at least one degree of freedom and loses control. Theoretically, such singularity occurs when the Forward Jacobian-matrix determinant becomes zero (Type II). However, actual PRs could lose control owing to Type II singularities for determinant values near zero, but not zero, because manufacturing tolerances introduce errors that are complex to model due to their low repeatability. Thus, using an actual 3UPS+RPU PR, this paper presents three contributions: i) a proximity detection index for Type II singularities based on the angle between two Output Twist Screws. The index can identify which kinematic chains contribute to the singularity. ii) an experimental benchmark to study Type II singularities. iii) PR configurations where the proposed index is zero and the Forward Jacobian determinant is not. In this last configuration, the findings show that the actual robot is unable to handle external actions applied to the PR.
format Preprint
id arxiv_https___arxiv_org_abs_2401_08229
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Experimental Analysis of Type II Singularities and Assembly Change Points in a 3UPS+RPU Parallel Robot
Pulloquinga, Jose L.
Mata, Vicente
Valera, Angel
Zamora-Ortiz, Pau
Diaz-Rodriguez, Miguel
Zambrano, Ivan
Robotics
Systems and Control
Parallel robots (PRs) have singular configurations where the robot gains at least one degree of freedom and loses control. Theoretically, such singularity occurs when the Forward Jacobian-matrix determinant becomes zero (Type II). However, actual PRs could lose control owing to Type II singularities for determinant values near zero, but not zero, because manufacturing tolerances introduce errors that are complex to model due to their low repeatability. Thus, using an actual 3UPS+RPU PR, this paper presents three contributions: i) a proximity detection index for Type II singularities based on the angle between two Output Twist Screws. The index can identify which kinematic chains contribute to the singularity. ii) an experimental benchmark to study Type II singularities. iii) PR configurations where the proposed index is zero and the Forward Jacobian determinant is not. In this last configuration, the findings show that the actual robot is unable to handle external actions applied to the PR.
title Experimental Analysis of Type II Singularities and Assembly Change Points in a 3UPS+RPU Parallel Robot
topic Robotics
Systems and Control
url https://arxiv.org/abs/2401.08229