A Primer on SO(3) Action Representations in Deep Reinforcement Learning

Fuente: arXiv
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Hauptverfasser: Schuck, Martin, Samy, Sherif, Schoellig, Angela P.
Format: Preprint
Veröffentlicht: 2025
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author Schuck, Martin
Samy, Sherif
Schoellig, Angela P.
author_facet Schuck, Martin
Samy, Sherif
Schoellig, Angela P.
contents Many robotic control tasks require policies to act on orientations, yet the geometry of SO(3) makes this nontrivial. Because SO(3) admits no global, smooth, minimal parameterization, common representations such as Euler angles, quaternions, rotation matrices, and Lie algebra coordinates introduce distinct constraints and failure modes. While these trade-offs are well studied for supervised learning, their implications for actions in reinforcement learning remain unclear. We systematically evaluate SO(3) action representations across three standard continuous control algorithms, PPO, SAC, and TD3, under dense and sparse rewards. We compare how representations shape exploration, interact with entropy regularization, and affect training stability through empirical studies and analyze the implications of different projections for obtaining valid rotations from Euclidean network outputs. Across a suite of robotics benchmarks, we quantify the practical impact of these choices and distill simple, implementation-ready guidelines for selecting and using rotation actions. Our results highlight that representation-induced geometry strongly influences exploration and optimization and show that representing actions as tangent vectors in the local frame yields the most reliable results across algorithms. The project webpage and code are available at amacati.github.io/so3 primer.
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id arxiv_https___arxiv_org_abs_2510_11103
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Primer on SO(3) Action Representations in Deep Reinforcement Learning
Schuck, Martin
Samy, Sherif
Schoellig, Angela P.
Robotics
Artificial Intelligence
Many robotic control tasks require policies to act on orientations, yet the geometry of SO(3) makes this nontrivial. Because SO(3) admits no global, smooth, minimal parameterization, common representations such as Euler angles, quaternions, rotation matrices, and Lie algebra coordinates introduce distinct constraints and failure modes. While these trade-offs are well studied for supervised learning, their implications for actions in reinforcement learning remain unclear. We systematically evaluate SO(3) action representations across three standard continuous control algorithms, PPO, SAC, and TD3, under dense and sparse rewards. We compare how representations shape exploration, interact with entropy regularization, and affect training stability through empirical studies and analyze the implications of different projections for obtaining valid rotations from Euclidean network outputs. Across a suite of robotics benchmarks, we quantify the practical impact of these choices and distill simple, implementation-ready guidelines for selecting and using rotation actions. Our results highlight that representation-induced geometry strongly influences exploration and optimization and show that representing actions as tangent vectors in the local frame yields the most reliable results across algorithms. The project webpage and code are available at amacati.github.io/so3 primer.
title A Primer on SO(3) Action Representations in Deep Reinforcement Learning
topic Robotics
Artificial Intelligence
url https://arxiv.org/abs/2510.11103