Curriculum Reinforcement Learning for Complex Reward Functions

Fuente: arXiv
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Autori principali: Freitag, Kilian, Ceder, Kristian, Laezza, Rita, Åkesson, Knut, Chehreghani, Morteza Haghir
Natura: Preprint
Pubblicazione: 2024
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author Freitag, Kilian
Ceder, Kristian
Laezza, Rita
Åkesson, Knut
Chehreghani, Morteza Haghir
author_facet Freitag, Kilian
Ceder, Kristian
Laezza, Rita
Åkesson, Knut
Chehreghani, Morteza Haghir
contents Reinforcement learning (RL) has emerged as a powerful tool for tackling control problems, but its practical application is often hindered by the complexity arising from intricate reward functions with multiple terms. The reward hypothesis posits that any objective can be encapsulated in a scalar reward function, yet balancing individual, potentially adversarial, reward terms without exploitation remains challenging. To overcome the limitations of traditional RL methods, which often require precise balancing of competing reward terms, we propose a two-stage reward curriculum that first maximizes a simple reward function and then transitions to the full, complex reward. We provide a method based on how well an actor fits a critic to automatically determine the transition point between the two stages. Additionally, we introduce a flexible replay buffer that enables efficient phase transfer by reusing samples from one stage in the next. We evaluate our method on the DeepMind control suite, modified to include an additional constraint term in the reward definitions. We further evaluate our method in a mobile robot scenario with even more competing reward terms. In both settings, our two-stage reward curriculum achieves a substantial improvement in performance compared to a baseline trained without curriculum. Instead of exploiting the constraint term in the reward, it is able to learn policies that balance task completion and constraint satisfaction. Our results demonstrate the potential of two-stage reward curricula for efficient and stable RL in environments with complex rewards, paving the way for more robust and adaptable robotic systems in real-world applications.
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id arxiv_https___arxiv_org_abs_2410_16790
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Curriculum Reinforcement Learning for Complex Reward Functions
Freitag, Kilian
Ceder, Kristian
Laezza, Rita
Åkesson, Knut
Chehreghani, Morteza Haghir
Machine Learning
Robotics
Reinforcement learning (RL) has emerged as a powerful tool for tackling control problems, but its practical application is often hindered by the complexity arising from intricate reward functions with multiple terms. The reward hypothesis posits that any objective can be encapsulated in a scalar reward function, yet balancing individual, potentially adversarial, reward terms without exploitation remains challenging. To overcome the limitations of traditional RL methods, which often require precise balancing of competing reward terms, we propose a two-stage reward curriculum that first maximizes a simple reward function and then transitions to the full, complex reward. We provide a method based on how well an actor fits a critic to automatically determine the transition point between the two stages. Additionally, we introduce a flexible replay buffer that enables efficient phase transfer by reusing samples from one stage in the next. We evaluate our method on the DeepMind control suite, modified to include an additional constraint term in the reward definitions. We further evaluate our method in a mobile robot scenario with even more competing reward terms. In both settings, our two-stage reward curriculum achieves a substantial improvement in performance compared to a baseline trained without curriculum. Instead of exploiting the constraint term in the reward, it is able to learn policies that balance task completion and constraint satisfaction. Our results demonstrate the potential of two-stage reward curricula for efficient and stable RL in environments with complex rewards, paving the way for more robust and adaptable robotic systems in real-world applications.
title Curriculum Reinforcement Learning for Complex Reward Functions
topic Machine Learning
Robotics
url https://arxiv.org/abs/2410.16790