Riemannian Formulation of Pontryagin’s Maximum Principle for the Optimal Control of Robotic Manipulators

In this work, we consider robotic systems for which the mass tensor is identified to be the metric in a Riemannian manifold. Cost functional invariance is achieved by constructing it with the identified metric. Optimal control evolution is revealed in the form of a covariant second-order ordinary di...

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Main Authors: Juan Antonio Rojas-Quintero, François Dubois, Hedy César Ramírez-de-Ávila
Format: Article
Language:English
Published: MDPI AG 2022-03-01
Series:Mathematics
Subjects:
Online Access:https://www.mdpi.com/2227-7390/10/7/1117
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author Juan Antonio Rojas-Quintero
François Dubois
Hedy César Ramírez-de-Ávila
author_facet Juan Antonio Rojas-Quintero
François Dubois
Hedy César Ramírez-de-Ávila
author_sort Juan Antonio Rojas-Quintero
collection DOAJ
description In this work, we consider robotic systems for which the mass tensor is identified to be the metric in a Riemannian manifold. Cost functional invariance is achieved by constructing it with the identified metric. Optimal control evolution is revealed in the form of a covariant second-order ordinary differential equation featuring the Riemann curvature tensor that constrains the control variable. In Pontryagin’s framework of the maximum principle, the cost functional has a direct impact on the system Hamiltonian. It is regarded as the performance index, and optimal control variables are affected by this fundamental choice. In the present context of cost functional invariance, we show that the adjoint variables are the first-order representation of the second-order control variable evolution equation. It is also shown that adding supplementary invariant terms to the cost functional does not modify the basic structure of the optimal control covariant evolution equation. Numerical trials show that the proposed invariant cost functionals, as compared to their non-invariant versions, lead to lower joint power consumption and narrower joint angular amplitudes during motion. With our formulation, the differential equations solver gains stability and operates dramatically faster when compared to examples where cost functional invariance is not considered.
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spelling doaj.art-c607221741064d3280a2c033ca303f902023-11-30T23:37:25ZengMDPI AGMathematics2227-73902022-03-01107111710.3390/math10071117Riemannian Formulation of Pontryagin’s Maximum Principle for the Optimal Control of Robotic ManipulatorsJuan Antonio Rojas-Quintero0François Dubois1Hedy César Ramírez-de-Ávila2CONACYT/Tecnológico Nacional de México/I.T. Ensenada, Ensenada 22780, BC, MexicoLaboratoire de Mathématiques d’Orsay, Université Paris-Saclay, Conservatoire National des Arts et Métiers, Structural Mechanics and Coupled Systems Laboratory, 75141 Paris, FranceTecnológico Nacional de México/I.T. Tijuana, Tijuana 22414, BC, MexicoIn this work, we consider robotic systems for which the mass tensor is identified to be the metric in a Riemannian manifold. Cost functional invariance is achieved by constructing it with the identified metric. Optimal control evolution is revealed in the form of a covariant second-order ordinary differential equation featuring the Riemann curvature tensor that constrains the control variable. In Pontryagin’s framework of the maximum principle, the cost functional has a direct impact on the system Hamiltonian. It is regarded as the performance index, and optimal control variables are affected by this fundamental choice. In the present context of cost functional invariance, we show that the adjoint variables are the first-order representation of the second-order control variable evolution equation. It is also shown that adding supplementary invariant terms to the cost functional does not modify the basic structure of the optimal control covariant evolution equation. Numerical trials show that the proposed invariant cost functionals, as compared to their non-invariant versions, lead to lower joint power consumption and narrower joint angular amplitudes during motion. With our formulation, the differential equations solver gains stability and operates dramatically faster when compared to examples where cost functional invariance is not considered.https://www.mdpi.com/2227-7390/10/7/1117optimal controlroboticsRiemannian geometryRiemann curvature tensorinvariancemultibody dynamics
spellingShingle Juan Antonio Rojas-Quintero
François Dubois
Hedy César Ramírez-de-Ávila
Riemannian Formulation of Pontryagin’s Maximum Principle for the Optimal Control of Robotic Manipulators
Mathematics
optimal control
robotics
Riemannian geometry
Riemann curvature tensor
invariance
multibody dynamics
title Riemannian Formulation of Pontryagin’s Maximum Principle for the Optimal Control of Robotic Manipulators
title_full Riemannian Formulation of Pontryagin’s Maximum Principle for the Optimal Control of Robotic Manipulators
title_fullStr Riemannian Formulation of Pontryagin’s Maximum Principle for the Optimal Control of Robotic Manipulators
title_full_unstemmed Riemannian Formulation of Pontryagin’s Maximum Principle for the Optimal Control of Robotic Manipulators
title_short Riemannian Formulation of Pontryagin’s Maximum Principle for the Optimal Control of Robotic Manipulators
title_sort riemannian formulation of pontryagin s maximum principle for the optimal control of robotic manipulators
topic optimal control
robotics
Riemannian geometry
Riemann curvature tensor
invariance
multibody dynamics
url https://www.mdpi.com/2227-7390/10/7/1117
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