KFCPO让强化学习更安全高效,自动调节奖励与约束的平衡。
KFCPO: Kronecker-Factored Approximated Constrained Policy Optimization
- 用分层闭式近似加速策略优化,避免迭代开销。
- 在安全环境测试中,平均收益比基线高10.3%至50.2%。
- 适合需要高安全性与稳定性的实际强化学习场景。
我们提出KFCPO,一种新型安全强化学习算法,结合可扩展的克罗内克积近似曲率(K-FAC)二阶策略优化与安全感知梯度调控。KFCPO通过分层闭式方式近似费雪信息矩阵(FIM),实现高效稳定的自然梯度更新,避免迭代逼近的开销。为解决奖励最大化与约束满足之间的权衡,引入基于裕度感知的梯度调控机制,根据智能体靠近安全边界程度自适应调整奖励与代价梯度的影响。该方法采用方向敏感投影融合梯度,消除有害干扰,并避免固定硬阈值带来的突变。此外,采用小批量层级的KL回滚策略,确保信任区域合规,防止策略剧烈波动。在Safety Gymnasium上使用OmniSafe进行实验,KFCPO在各类环境中相比最优安全基线,平均回报提升10.3%至50.2%,展现出优异的安全性与性能平衡。
原文摘要 · Abstract (English)
We propose KFCPO, a novel Safe Reinforcement Learning (Safe RL) algorithm that combines scalable Kronecker-Factored Approximate Curvature (K-FAC) based second-order policy optimization with safety-aware gradient manipulation. KFCPO leverages K-FAC to perform efficient and stable natural gradient updates by approximating the Fisher Information Matrix (FIM) in a layerwise, closed form manner, avoiding iterative approximation overheads. To address the tradeoff between reward maximization and constraint satisfaction, we introduce a margin aware gradient manipulation mechanism that adaptively adjusts the influence of reward and cost gradients based on the agent's proximity to safety boundaries. This method blends gradients using a direction sensitive projection, eliminating harmful interference and avoiding abrupt changes caused by fixed hard thresholds. Additionally, a minibatch level KL rollback strategy is adopted to ensure trust region compliance and to prevent destabilizing policy shifts. Experiments on Safety Gymnasium using OmniSafe show that KFCPO achieves 10.3% to 50.2% higher average return across environments compared to the best baseline that respected the safety constraint, demonstrating superior balance of safety and performance.
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