Cited by 831Reinforcement Learning in RoboticsMotor Control and AdaptationAdaptive Dynamic Programming Control

Reinforcement learning of motor skills with policy gradients

Peters, Jan, Schaal, Stefan·2008·Neural Networks

Abstract

Autonomous learning is one of the hallmarks of human and animal behavior, and understanding the principles of learning will be crucial in order to achieve true autonomy in advanced machines like humanoid robots. In this paper, we examine learning of complex motor skills with human-like limbs. While supervised learning can offer useful tools for bootstrapping behavior, e.g., by learning from demonstration, it is only reinforcement learning that offers a general approach to the final trial-and-error improvement that is needed by each individual acquiring a skill. Neither neurobiological nor machine learning studies have, so far, offered compelling results on how reinforcement learning can be scaled to the high-dimensional continuous state and action spaces of humans or humanoids. Here, we combine two recent research developments on learning motor control in order to achieve this scaling. First, we interpret the idea of modular motor control by means of motor primitives as a suitable way to generate parameterized control policies for reinforcement learning. Second, we combine motor primitives with the theory of stochastic policy gradient learning, which currently seems to be the only feasible framework for reinforcement learning for humanoids. We evaluate different policy gradient methods with a focus on their applicability to parameterized motor primitives. We compare these algorithms in the context of motor primitive learning, and show that our most modern algorithm, the Episodic Natural Actor-Critic outperforms previous algorithms by at least an order of magnitude. We demonstrate the efficiency of this reinforcement learning method in the application of learning to hit a baseball with an anthropomorphic robot arm.

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Crossref · 10.1016/j.neunet.2008.02.003

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  • Comparator models are agnostic regarding the specific mathematical computation underlying their function, which can be explained by a variety of Bayesian or non-Bayesian mechanisms.

    “Crucially, comparator models are agnostic regarding the specific mathematical computation underlying their function, which can be explained by a variety of Bayesian (e.g., variational Bayes, Kalman filtering) or non-Bayesian mechanisms (e.g., reinforcement learning) (Friston 2011; Peters and Schaal 2008; Wolpert et al. 1995).”

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Authors
Peters, J., & Schaal, S.
Affiliations
University of Southern California (US)
Corresponding author
Peters, Jan
Venue
Neural Networks
Publisher
Elsevier BV
Published
2008-05
Volume
21
Issue
4
Pages
682-697
ISSN
0893-6080 (ISSN-L)
OpenAlex
W2125612430
Cited by
831
References
77
Citations by year
2026: 19 · 2025: 27 · 2024: 43 · 2023: 50 · 2022: 49 · 2021: 62 · 2020: 75 · 2019: 77 · 2018: 80 · 2017: 71 · 2016: 39 · 2015: 31 · 2014: 45 · 2013: 43 · 2012: 44
FWCI
39.57
Type
journal article
Language
en
Open access
closed
Locations
  • Neural Networks (publishedVersion)
  • PubMed (publishedVersion)
  • TUbilio (Technical University of Darmstadt) (acceptedVersion)
  • Max Planck Institute for Plasma Physics (submittedVersion)
  • MPG.PuRe (Max Planck Society) (submittedVersion)
Topics
  • Physical Sciences › Computer Science › Artificial Intelligence › Reinforcement Learning in Robotics
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Motor Control and Adaptation
  • Physical Sciences › Computer Science › Computational Theory and Mathematics › Adaptive Dynamic Programming Control
Keywords
reinforcement learning, motor skill learning, policy gradient, motor primitives, humanoid robots, anthropomorphic robot arm
MeSH terms
Algorithms, Animals, Artificial Intelligence, Computer Simulation, Extremities, Feedback, Forelimb, Humans, Locomotion, Motor Skills, Movement, Reinforcement, Psychology, Robotics, Stochastic Processes

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