arXiv:2603.18326cs.LG2026-03

用向量场奖励引导智能体安全探索数据边界,避免僵化停驻。

Escaping Offline Pessimism: Vector-Field Reward Shaping for Safe Frontier Exploration

  • 基于离线数据构建不确定性原语,设计梯度对齐与旋转向量场双组件奖励
  • 在2D导航任务中实现持续边界探索,兼顾任务完成与安全数据收集
  • 适合部署非自适应策略的场景,解决离线强化学习的保守性问题

离线强化学习虽能提供可靠策略,但其固有的保守性严重限制了智能体在线探索与新数据收集能力。受安全强化学习启发,我们提出一种向量场奖励塑造方法,引导智能体在离线数据覆盖充分且仿真模型可靠的区域边界附近进行可控探索——既进入信息丰富但不确定性适中的状态,又保持足够接近熟悉区域以实现安全回溯。然而,简单奖励边界行为会导致智能体到达边界后停滞不动(即‘停车’退化)。为此,我们设计了一种新型向量场奖励机制:基于从离线数据训练的不确定性原语,结合梯度对齐项(吸引至目标不确定性水平)和旋转向量场项(沿不确定性流形局部切平面推动运动),理论上可自然诱导持续探索行为并避免退化解。实验中,将该奖励与Soft Actor-Critic结合,在2D连续导航任务上验证了智能体能够有效穿越不确定性边界,同时平衡主任务完成与安全、高信息量的数据采集。

原文摘要 · Abstract (English)

While offline reinforcement learning provides reliable policies for real-world deployment, its inherent pessimism severely restricts an agent's ability to explore and collect novel data online. Drawing inspiration from safe reinforcement learning, exploring near the boundary of regions well covered by the offline dataset and reliably modeled by the simulator allows an agent to take manageable risks--venturing into informative but moderate-uncertainty states while remaining close enough to familiar regions for safe recovery. However, naively rewarding this boundary-seeking behavior can lead to a degenerate parking behavior, where the agent simply stops once it reaches the frontier. To solve this, we propose a novel vector-field reward shaping paradigm designed to induce continuous, safe boundary exploration for non-adaptive deployed policies. Operating on an uncertainty oracle trained from offline data, our reward combines two complementary components: a gradient-alignment term that attracts the agent toward a target uncertainty level, and a rotational-flow term that promotes motion along the local tangent plane of the uncertainty manifold. Through theoretical analysis, we show that this reward structure naturally induces sustained exploratory behavior along the boundary while preventing degenerate solutions. Empirically, by integrating our proposed reward shaping with Soft Actor-Critic on a 2D continuous navigation task, we validate that agents successfully traverse uncertainty boundaries while balancing safe, informative data collection with primary task completion.

强化学习离线学习奖励塑形安全探索

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