提出新方法防范奖励欺骗,让智能体在奖励不完美时仍稳定表现。
Robust Optimization for Mitigating Reward Hacking with Correlated Proxies

- 构建对抗最坏相关代理奖励的鲁棒优化框架
- 实验显示在不同相关性下均优于ORPO, worst-case回报更高
- 可结合已知特征提升可解释性,适合奖励设计不确定的场景
在奖励信号不完善的情况下设计稳健的强化学习智能体仍是核心挑战。实践中,智能体常使用近似真实目标的代理奖励进行训练,易产生奖励欺骗——即通过非预期或投机行为获得高代理回报。现有工作用代理与真实奖励之间的r-相关性形式化该问题,但如占用正则化策略优化(ORPO)等方法仅针对固定代理优化,无法对更广泛的相关代理提供强保障。本文将奖励欺骗建模为所有r-相关代理奖励空间上的鲁棒策略优化问题,推导出可计算的极大极小公式:智能体在与相关性约束一致的最坏代理奖励下最大化性能。当奖励是已知特征的线性函数时,方法可融合先验知识,生成更优策略与可解释的最坏情况奖励。多个环境的实验表明,本方法在不同代理-真实奖励相关性水平下,始终优于ORPO,显著提升最坏情况回报、鲁棒性与稳定性。结果表明该方法在奖励设计固有不确定的场景中兼具鲁棒性与透明性。代码已开源。
原文摘要 · Abstract (English)
Designing robust reinforcement learning (RL) agents in the presence of imperfect reward signals remains a core challenge. In practice, agents are often trained with proxy rewards that only approximate the true objective, leaving them vulnerable to reward hacking, where high proxy returns arise from unintended or exploitative behaviors. Recent work formalizes this issue using r-correlation between proxy and true rewards, but existing methods like occupancy-regularized policy optimization (ORPO) optimize against a fixed proxy and do not provide strong guarantees against broader classes of correlated proxies. In this work, we formulate reward hacking as a robust policy optimization problem over the space of all r-correlated proxy rewards. We derive a tractable max-min formulation, where the agent maximizes performance under the worst-case proxy consistent with the correlation constraint. We further show that when the reward is a linear function of known features, our approach can be adapted to incorporate this prior knowledge, yielding both improved policies and interpretable worst-case rewards. Experiments across several environments show that our algorithms consistently outperform ORPO in worst-case returns, and offer improved robustness and stability across different levels of proxy-true reward correlation. These results show that our approach provides both robustness and transparency in settings where reward design is inherently uncertain. The code is available at https://github.com/ZixuanLiu4869/reward_hacking.
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