Return-Aligned Decision Transformer (2402.03923v4)

Abstract: Traditional approaches in offline reinforcement learning aim to learn the optimal policy that maximizes the cumulative reward, also known as return. However, as applications broaden, it becomes increasingly crucial to train agents that not only maximize the returns, but align the actual return with a specified target return, giving control over the agent's performance. Decision Transformer (DT) optimizes a policy that generates actions conditioned on the target return through supervised learning and is equipped with a mechanism to control the agent using the target return. However, the action generation is hardly influenced by the target return because DT's self-attention allocates scarce attention scores to the return tokens. In this paper, we propose Return-Aligned Decision Transformer (RADT), designed to effectively align the actual return with the target return. RADT utilizes features extracted by paying attention solely to the return, enabling the action generation to consistently depend on the target return. Extensive experiments show that RADT reduces the discrepancies between the actual return and the target return of DT-based methods.