A Type II Singularity Avoidance Algorithm for Parallel Manipulators using Output Twist Screws

Fuente: arXiv
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Main Authors: Pulloquinga, Jose L., Escarabajal, Rafael J., Valera, Angel, Valles, Marina, Mata, Vicente
Format: Preprint
Published: 2024
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author Pulloquinga, Jose L.
Escarabajal, Rafael J.
Valera, Angel
Valles, Marina
Mata, Vicente
author_facet Pulloquinga, Jose L.
Escarabajal, Rafael J.
Valera, Angel
Valles, Marina
Mata, Vicente
contents Parallel robots (PRs) are closed-chain manipulators with diverse applications due to their accuracy and high payload. However, there are configurations within the workspace named Type II singularities where the PRs lose control of the end-effector movements. Type II singularities are a problem for applications where complete control of the end-effector is essential. Trajectory planning produces accurate movements of a PR by avoiding Type II singularities. Generally, singularity avoidance is achieved by optimising a geometrical path with a velocity profile considering singular configurations as obstacles. This research presents an algorithm that avoids Type II singularities by modifying the trajectory of a subset of the actuators. The subset of actuators represents the limbs responsible for a Type II singularity, and they are identified by the angle between two Output Twist Screws. The proposed avoidance algorithm does not require optimisation procedures, which reduces the computational cost for offline trajectory planning and makes it suitable for online trajectory planning. The avoidance algorithm is implemented in offline trajectory planning for a pick and place planar PR and a spatial knee rehabilitation PR
format Preprint
id arxiv_https___arxiv_org_abs_2401_09115
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A Type II Singularity Avoidance Algorithm for Parallel Manipulators using Output Twist Screws
Pulloquinga, Jose L.
Escarabajal, Rafael J.
Valera, Angel
Valles, Marina
Mata, Vicente
Robotics
Systems and Control
Parallel robots (PRs) are closed-chain manipulators with diverse applications due to their accuracy and high payload. However, there are configurations within the workspace named Type II singularities where the PRs lose control of the end-effector movements. Type II singularities are a problem for applications where complete control of the end-effector is essential. Trajectory planning produces accurate movements of a PR by avoiding Type II singularities. Generally, singularity avoidance is achieved by optimising a geometrical path with a velocity profile considering singular configurations as obstacles. This research presents an algorithm that avoids Type II singularities by modifying the trajectory of a subset of the actuators. The subset of actuators represents the limbs responsible for a Type II singularity, and they are identified by the angle between two Output Twist Screws. The proposed avoidance algorithm does not require optimisation procedures, which reduces the computational cost for offline trajectory planning and makes it suitable for online trajectory planning. The avoidance algorithm is implemented in offline trajectory planning for a pick and place planar PR and a spatial knee rehabilitation PR
title A Type II Singularity Avoidance Algorithm for Parallel Manipulators using Output Twist Screws
topic Robotics
Systems and Control
url https://arxiv.org/abs/2401.09115