Rethinking Value Function Learning for Generalization in Reinforcement Learning
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We focus on the problem of training RL agents on multiple training environments to improve observational generalization performance. In prior methods, policy and value networks are separately optimized using a disjoint network architecture to avoid interference and obtain a more accurate value function. We identify that the value network in the multiple-environment setting is more challenging to optimize and prone to overfitting training data than in the conventional single-environment setting. In addition, we find that appropriate regularization of the value network is required for better training and test performance. To this end, we propose Delayed-Critic Policy Gradient (DCPG), which implicitly penalizes the value estimates by optimizing the value network less frequently with more training data than the policy network, which can be implemented using a shared network architecture. Furthermore, we introduce a simple self-supervised task that learns the forward and inverse dynamics of environments using a single discriminator, which can be jointly optimized with the value network. Our proposed algorithms significantly improve observational generalization performance and sample efficiency in the Procgen Benchmark.
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