CACTO-SL: Using Sobolev Learning to improve Continuous Actor-Critic with Trajectory Optimization

Fuente: arXiv
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Main Authors: Alboni, Elisa, Grandesso, Gianluigi, Papini, Gastone Pietro Rosati, Carpentier, Justin, Del Prete, Andrea
Format: Preprint
Published: 2023
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author Alboni, Elisa
Grandesso, Gianluigi
Papini, Gastone Pietro Rosati
Carpentier, Justin
Del Prete, Andrea
author_facet Alboni, Elisa
Grandesso, Gianluigi
Papini, Gastone Pietro Rosati
Carpentier, Justin
Del Prete, Andrea
contents Trajectory Optimization (TO) and Reinforcement Learning (RL) are powerful and complementary tools to solve optimal control problems. On the one hand, TO can efficiently compute locally-optimal solutions, but it tends to get stuck in local minima if the problem is not convex. On the other hand, RL is typically less sensitive to non-convexity, but it requires a much higher computational effort. Recently, we have proposed CACTO (Continuous Actor-Critic with Trajectory Optimization), an algorithm that uses TO to guide the exploration of an actor-critic RL algorithm. In turns, the policy encoded by the actor is used to warm-start TO, closing the loop between TO and RL. In this work, we present an extension of CACTO exploiting the idea of Sobolev learning. To make the training of the critic network faster and more data efficient, we enrich it with the gradient of the Value function, computed via a backward pass of the differential dynamic programming algorithm. Our results show that the new algorithm is more efficient than the original CACTO, reducing the number of TO episodes by a factor ranging from 3 to 10, and consequently the computation time. Moreover, we show that CACTO-SL helps TO to find better minima and to produce more consistent results.
format Preprint
id arxiv_https___arxiv_org_abs_2312_10666
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle CACTO-SL: Using Sobolev Learning to improve Continuous Actor-Critic with Trajectory Optimization
Alboni, Elisa
Grandesso, Gianluigi
Papini, Gastone Pietro Rosati
Carpentier, Justin
Del Prete, Andrea
Robotics
Machine Learning
Optimization and Control
Trajectory Optimization (TO) and Reinforcement Learning (RL) are powerful and complementary tools to solve optimal control problems. On the one hand, TO can efficiently compute locally-optimal solutions, but it tends to get stuck in local minima if the problem is not convex. On the other hand, RL is typically less sensitive to non-convexity, but it requires a much higher computational effort. Recently, we have proposed CACTO (Continuous Actor-Critic with Trajectory Optimization), an algorithm that uses TO to guide the exploration of an actor-critic RL algorithm. In turns, the policy encoded by the actor is used to warm-start TO, closing the loop between TO and RL. In this work, we present an extension of CACTO exploiting the idea of Sobolev learning. To make the training of the critic network faster and more data efficient, we enrich it with the gradient of the Value function, computed via a backward pass of the differential dynamic programming algorithm. Our results show that the new algorithm is more efficient than the original CACTO, reducing the number of TO episodes by a factor ranging from 3 to 10, and consequently the computation time. Moreover, we show that CACTO-SL helps TO to find better minima and to produce more consistent results.
title CACTO-SL: Using Sobolev Learning to improve Continuous Actor-Critic with Trajectory Optimization
topic Robotics
Machine Learning
Optimization and Control
url https://arxiv.org/abs/2312.10666