Optimal Reconfiguration of a Parallel Robot for Forward Singularities Avoidance in Rehabilitation Therapies. A Comparison via Different Optimization Methods

Llopis-Albert, Carlos; Valero, Francisco; Mata, Vicente; Pulloquinga, José L.; Zamora-Ortiz, Pau; Escarabajal, Rafael J.

doi:10.3390/su12145803

Open AccessArticle

Optimal Reconfiguration of a Parallel Robot for Forward Singularities Avoidance in Rehabilitation Therapies. A Comparison via Different Optimization Methods

by

Carlos Llopis-Albert

^*

,

Francisco Valero

,

Vicente Mata

,

José L. Pulloquinga

,

Pau Zamora-Ortiz

and

Rafael J. Escarabajal

Centro de Investigación en Ingeniería Mecánica (CIIM), Universitat Politècnica de València–Camino de Vera s/n, 46022 Valencia, Spain

^*

Author to whom correspondence should be addressed.

Sustainability 2020, 12(14), 5803; https://doi.org/10.3390/su12145803

Submission received: 13 May 2020 / Revised: 9 July 2020 / Accepted: 16 July 2020 / Published: 19 July 2020

(This article belongs to the Special Issue Machine Learning and Robots for Sustainability)

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Abstract

This paper presents an efficient algorithm for the reconfiguration of a parallel kinematic manipulator with four degrees of freedom. The reconfiguration of the parallel manipulator is posed as a nonlinear optimization problem where the design variables correspond to the anchoring points of the limbs of the robot on the fixed platform. The penalty function minimizes the forces applied by the actuators during a specific trajectory. Some constraints are imposed to avoid forward singularities and guarantee the feasibility of the active generalized coordinates for a certain trajectory. The results are compared with different optimization approaches with the aim of avoiding getting trapped into a local minimum and undergoing forward singularities. The comparison covers evolutionary algorithms, heuristics optimizers, multistrategy algorithms, and gradient-based optimizers. The proposed methodology has been successfully tested on an actual parallel robot for different trajectories.

Keywords: parallel robot; rehabilitation; reconfiguration; optimization; trajectory planning; direct singularities

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MDPI and ACS Style

Llopis-Albert, C.; Valero, F.; Mata, V.; Pulloquinga, J.L.; Zamora-Ortiz, P.; Escarabajal, R.J. Optimal Reconfiguration of a Parallel Robot for Forward Singularities Avoidance in Rehabilitation Therapies. A Comparison via Different Optimization Methods. Sustainability 2020, 12, 5803. https://doi.org/10.3390/su12145803

AMA Style

Llopis-Albert C, Valero F, Mata V, Pulloquinga JL, Zamora-Ortiz P, Escarabajal RJ. Optimal Reconfiguration of a Parallel Robot for Forward Singularities Avoidance in Rehabilitation Therapies. A Comparison via Different Optimization Methods. Sustainability. 2020; 12(14):5803. https://doi.org/10.3390/su12145803

Chicago/Turabian Style

Llopis-Albert, Carlos, Francisco Valero, Vicente Mata, José L. Pulloquinga, Pau Zamora-Ortiz, and Rafael J. Escarabajal. 2020. "Optimal Reconfiguration of a Parallel Robot for Forward Singularities Avoidance in Rehabilitation Therapies. A Comparison via Different Optimization Methods" Sustainability 12, no. 14: 5803. https://doi.org/10.3390/su12145803

APA Style

Llopis-Albert, C., Valero, F., Mata, V., Pulloquinga, J. L., Zamora-Ortiz, P., & Escarabajal, R. J. (2020). Optimal Reconfiguration of a Parallel Robot for Forward Singularities Avoidance in Rehabilitation Therapies. A Comparison via Different Optimization Methods. Sustainability, 12(14), 5803. https://doi.org/10.3390/su12145803

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Optimal Reconfiguration of a Parallel Robot for Forward Singularities Avoidance in Rehabilitation Therapies. A Comparison via Different Optimization Methods

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