arXiv AI
Oct 5

Multi-Fidelity Policy Gradients Stabilize Data-Scarce Reinforcement Learning

The paper introduces Multi‑Fidelity Policy Gradient (MFPG) methods that combine scarce, high‑fidelity (HF) reinforcement‑learning data with abundant, low‑fidelity (LF) data to stabilize training. Unlike prior approaches that directly optimize biased LF objectives, MFPG uses LF data only to construct a control variate that reduces variance without biasing the policy gradient. The authors extend MFPG to modern actor‑critic algorithms, notably a budget‑aware MFPG‑PPO that preserves cross‑fidelity correlation, monitors estimator uncertainty, and allocates a fixed sampling budget between HF and LF sources. Experiments on simulated robot locomotion and a physical Franka arm show that MFPG‑PPO consistently outperforms standard PPO trained on HF data alone and matches performance achieved with 16× more HF data on the hardest tasks, while enabling stable learning with as few as four real‑robot episodes per update.

By Xinjie Liu, Ruihan Zhao, Anirban Chaudhuri, Cyrus Neary, Ufuk Topcu, David Fridovich-Keil
arXiv Machine Learning
Jun 11

OGPO: Sample Efficient Full-Finetuning of Generative Control Policies

arXiv:2605. 03065v2 Announce Type: replace Abstract: Generative control policies (GCPs), such as diffusion- and flow-based control policies, have emerged as effective parameterizations for robot learning.

By Sarvesh Patil, Mitsuhiko Nakamoto, Manan Agarwal, Shashwat Saxena, Jesse Zhang, Giri Anantharaman, Cleah Winston, Chaoyi Pan, Douglas Chen, Nai-Chieh Huang, Zeynep Temel, Oliver Kroemer, Sergey Levine, Abhishek Gupta, Hongkai Dai, Paarth Shah, Max Simchowitz
arXiv Machine Learning
3d ago

Best Policy Tracking in Reinforcement Learning

The paper investigates how non‑monotonic performance dynamics in single‑task reinforcement learning affect policy selection. By introducing post‑hoc diagnostic metrics, the authors evaluate common selection strategies on continuous‑control benchmarks and find that typical practices often miss the best policy, leading to suboptimal performance and wasted computation. They propose a validation‑based selection method that better approximates the best visited policy while improving efficiency.

By Judith Echevarrieta, Etor Arza, Aritz P\'erez, Josu Ceberio
arXiv AI
Jun 6

Retry Policy Gradients in Continuous Action Spaces

arXiv:2606. 05888v1 Announce Type: new Abstract: Retry-based objectives such as pass@K and max@K optimize the best return obtained from multiple sampled trajectories, and recent work has shown that they can promote exploration without explicit exploration bonuses.

By Soichiro Nishimori, Paavo Parmas