改进强化学习的更新机制,让智能体在变化环境中更灵活地切换行为。
Local Guidance, Global Impact: Gaussian-Reshaped Trust Region Unlocks Behavior Transitions

- 用高斯核重塑信任区域,实现局部稳定与动态放松的平衡
- 在连续环境和语言模型微调中显著提升适应能力,避免无效更新
- 适合需要长期适应的复杂非平稳任务,如机器人控制与开放世界探索
尽管近端策略优化(PPO)在静态环境下表现良好,但在持续性与非平稳环境中表现不佳。问题并非模型容量不足或裁剪过严,而是其持续进行方向低效的局部更新,缺乏对行为变化几何结构的引导,阻碍了新行为模式的过渡。尽管基于发散的正则化引入部分几何感知,但单调递增的惩罚会隐式抑制必要的大范围策略偏移。为此,我们提出高斯信任区域策略优化(GTR),通过高斯核重塑信任区域,使约束具有界且非单调,既保障局部稳定性,又在持续高优势更新下逐步放松。为进一步增强鲁棒性,引入混合高斯锚点,自适应近期策略轨迹,降低由陈旧参考引发的方差。GTR不依赖特定架构,在游戏、模拟机器人控制、开放世界探索及语言模型后训练中均表现优异。结果表明,具备几何感知的信任区域设计是复杂非平稳环境中强化学习的可行方向。代码已公开于 https://anonymous.4open.science/r/GTR_demo/README.md。
原文摘要 · Abstract (English)
While Proximal Policy Optimization (PPO) demonstrates strong performance in stationary settings, we show that its standard optimization paradigm struggles in continual and non-stationary environments. The failure does not stem from insufficient model capacity or overly restrictive clipping. Instead, PPO performs persistent, directionally inefficient local updates, which indicates a lack of geometry-aware guidance for accumulating meaningful behavioral change and ultimately hindering transitions toward new behavior patterns. Although divergence-based regularization introduces partial geometric awareness, its monotonically increasing penalties implicitly discourage large policy deviations, even when such shifts are necessary for effective adaptation. To address this limitation, we propose Gaussian Trust Region Policy Optimization (GTR), which reshapes the trust region using a Gaussian kernel. The resulting constraint is bounded and non-monotonic, providing strong local stability while progressively relaxing under sustained high-advantage updates. To further improve robustness, we introduce a Mixture Gaussian Anchor that adapts to recent policy trajectories, reducing variance induced by stale references. GTR is architecture-agnostic and achieves strong performance across games, simulated robotic control, open-world exploration, and language model post-training. These results demonstrate that geometry-aware trust-region design can be a promising direction for robust reinforcement learning in complex non-stationary environments. Our code is available at https://anonymous.4open.science/r/GTR_demo/README.md.
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