Keywords: reinforcement learning, constraint optimization, underestimation, intrinsic cost
Abstract: Constrained Reinforcement Learning (CRL) aims to maximize cumulative rewards while satisfying constraints. However, most existing CRL algorithms encounter significant constraint violations during training, limiting their applicability in safety-critical scenarios. In this paper, we identify the underestimation of the cost value function as a key factor contributing to these violations. To address this issue, we propose the Memory-driven Intrinsic Cost Estimation (MICE) method, which introduces intrinsic costs to enhance the cost estimate of unsafe behaviors, thus mitigating the underestimation bias. Our method draws inspiration from human cognitive processes, specifically the concept of flashbulb memory, where vivid memories of dangerous events are retained to prevent potential risks. MICE constructs a memory module to store unsafe trajectories explored by the agent. The intrinsic cost is formulated as the similarity between the current trajectory and the unsafe trajectories stored in memory, assessed by an intrinsic generator. We propose an extrinsic-intrinsic cost value function and optimization objective based on intrinsic cost, along with the corresponding optimization method. Theoretically, we provide convergence guarantees for the new cost value function and establish the worst-case constraint violation for the MICE update, ensuring fewer constraint violations compared to baselines. Extensive experiments validate the effectiveness of our approach, demonstrating a substantial reduction in constraint violations while maintaining policy performance comparable to baselines.
Primary Area: reinforcement learning
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Submission Number: 6568
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