arXiv:2505.15514cs.LGcs.AI2025-05被引 2

通过动态调节优势信号,提升PPO算法的训练稳定性和效率。

AM-PPO: (Advantage) Alpha-Modulation with Proximal Policy Optimization

  • 用自适应非线性缩放机制动态调节优势值,减少噪声和方差。
  • 在连续控制任务中实现更优奖励曲线,降低优化器剪裁需求。
  • 适合需要稳定强化学习训练的研究者和工业应用。

近端策略优化(PPO)是一种广泛使用的强化学习算法,其性能高度依赖于准确的优势估计。然而,原始优势信号常存在显著方差、噪声和尺度问题,影响学习效果。为此,本文提出优势调制PPO(AM-PPO),引入一种基于动态非线性缩放机制的自适应优势调制方法。该机制通过一个α控制器,根据优势信号的范数、方差及预设饱和水平动态调整缩放因子,并结合tanh门控函数重塑优势信号,从而稳定梯度更新并改善策略梯度空间的条件性。关键的是,该调制还为价值函数训练提供一致且自适应的学习目标。在标准连续控制基准测试中的实证结果表明,AM-PPO实现了更优的奖励轨迹,展现出持续的学习进展,并显著减少了自适应优化器所需的剪裁量。这些发现凸显了优势调制作为通用强化学习优化技术的潜力。

原文摘要 · Abstract (English)

Proximal Policy Optimization (PPO) is a widely used reinforcement learning algorithm that heavily relies on accurate advantage estimates for stable and efficient training. However, raw advantage signals can exhibit significant variance, noise, and scale-related issues, impeding optimal learning performance. To address this challenge, we introduce Advantage Modulation PPO (AM-PPO), a novel enhancement of PPO that adaptively modulates advantage estimates using a dynamic, non-linear scaling mechanism. This adaptive modulation employs an alpha controller that dynamically adjusts the scaling factor based on evolving statistical properties of the advantage signals, such as their norm, variance, and a predefined target saturation level. By incorporating a tanh-based gating function driven by these adaptively scaled advantages, AM-PPO reshapes the advantage signals to stabilize gradient updates and improve the conditioning of the policy gradient landscape. Crucially, this modulation also influences value function training by providing consistent and adaptively conditioned learning targets. Empirical evaluations across standard continuous control benchmarks demonstrate that AM-PPO achieves superior reward trajectories, exhibits sustained learning progression, and significantly reduces the clipping required by adaptive optimizers. These findings underscore the potential of advantage modulation as a broadly applicable technique for enhancing reinforcement learning optimization.

强化学习PPO改进优势估计

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