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Flow Matching Policy Gradients

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arxiv 2507.21053 v2 pith:XTWI2FWN submitted 2025-07-28 cs.LG cs.RO

classification cs.LGcs.RO
keywords flowmodelspolicyflow-basedmatchingcontinuousdiffusiondistributions
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Flow-based generative models, including diffusion models, excel at modeling continuous distributions in high-dimensional spaces. In this work, we introduce Flow Policy Optimization (FPO), a simple on-policy reinforcement learning algorithm that brings flow matching into the policy gradient framework. FPO casts policy optimization as maximizing an advantage-weighted ratio computed from the conditional flow matching loss, in a manner compatible with the popular PPO-clip framework. It sidesteps the need for exact likelihood computation while preserving the generative capabilities of flow-based models. Unlike prior approaches for diffusion-based reinforcement learning that bind training to a specific sampling method, FPO is agnostic to the choice of diffusion or flow integration at both training and inference time. We show that FPO can train diffusion-style policies from scratch in a variety of continuous control tasks. We find that flow-based models can capture multimodal action distributions and achieve higher performance than Gaussian policies, particularly in under-conditioned settings.

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Cited by 37 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Test-Time Gradient Guidance of Flow Policies in Reinforcement Learning

    cs.LG 2026-06 unverdicted novelty 7.0 of 10

    QGF performs test-time policy optimization for flow models in RL by guiding a behavior-cloned reference policy with value-function gradients, achieving strong results on high-dimensional offline RL benchmarks without ...

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  3. Explicit Critic Guidance for Aligning Diffusion Models

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    Introduces a state-aligned latent actor-critic framework that lets diffusion models act as their own timestep-conditioned value functions for trajectory-level RL post-training and inference steering.

  4. DISA: Offline Importance Sampling for Distribution-Matching LLM-RL

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  5. Preserving Foundational Capabilities in Flow-Matching VLAs through Conservative SFT

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    ConSFT prevents catastrophic forgetting in fine-tuning flow-matching VLAs by dynamically scaling gradients based on model confidence, retaining over 20% more pre-trained capability than standard SFT without prior data...

  6. Generative Actor-Critic with Soft Bridge Policies

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  7. Genuine pair density wave order on the kagome lattice

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  8. Support-Constrained RL Enables Real-World Policy Improvement without Real-World Experience

    cs.RO 2026-06 unverdicted novelty 6.0 of 10

    SCORE constrains sim RL to the support of a real-data policy via flow steering, raising average success on eight dexterous tasks from 37.8% to 89.9%.

  9. Transferring Contact, Not Just Motion: Compliant Grasping Across Dexterous Hands

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  10. DiPOD: Diffusion Policy Optimization without Drifting Apart

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  11. GenPO++: Generative Policy Optimization with Jacobian-free Likelihood Ratios

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    GenPO++ achieves exact Jacobian-free likelihood ratio computation for generative flow policies by embedding history states as auxiliary memory in a high-order reversible ODE solver.

  12. GDSD: Reinforcement Learning as Guided Denoiser Self-Distillation for Diffusion Language Models

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    GDSD reduces RL for dLLMs to likelihood-free self-distillation via a normalization-free logit-matching objective, outperforming ELBO methods with more stable training on LLaDA-8B and Dream-7B.

  13. Adversarial Dual On-Policy Distillation from Expressive Teacher

    cs.LG 2026-05 unverdicted novelty 6.0 of 10

    FA-OPD co-trains a flow-matching teacher and MLP student via adversarial dual on-policy distillation, improving robustness over baselines on six robot benchmarks with noisy or limited demonstrations.

  14. DEFLECT: Delay-Robust Execution via Flow-matching Likelihood-Estimated Counterfactual Tuning for VLA Policies

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    DEFLECT is an offline post-training method that improves async VLA policy success rates under high inference delays by using flow-matching likelihood ratios on counterfactual fresh/stale action pairs from a frozen ref...

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  17. Discrete Flow Matching for Offline-to-Online Reinforcement Learning

    cs.LG 2026-05 unverdicted novelty 6.0 of 10

    DRIFT enables stable offline-to-online fine-tuning of CTMC policies in discrete RL via advantage-weighted discrete flow matching, path-space regularization, and candidate-set approximation.

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    UniSteer unifies human corrective actions and noise-space RL for VLA adaptation by inverting actions to noise targets, raising success rates from 20% to 90% in 66 minutes across four real-world manipulation tasks.

  19. UniSteer: Unified Noise Steering for Efficient Human-Guided VLA Adaptation

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  20. OGPO: Sample Efficient Full-Finetuning of Generative Control Policies

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  21. OGPO: Sample Efficient Full-Finetuning of Generative Control Policies

    cs.LG 2026-05 unverdicted novelty 6.0 of 10

    OGPO is a sample-efficient off-policy method for full finetuning of generative control policies that reaches SOTA on robotic manipulation tasks and can recover from poor behavior-cloning initializations without expert data.

  22. V-GRPO: Online Reinforcement Learning for Denoising Generative Models Is Easier than You Think

    cs.LG 2026-04 unverdicted novelty 6.0 of 10

    V-GRPO makes ELBO surrogates stable and efficient for online RL alignment of denoising models, delivering SOTA text-to-image performance with 2-3x speedups over MixGRPO and DiffusionNFT.

  23. Positive-Only Drifting Policy Optimization

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  24. FP4 Explore, BF16 Train: Diffusion Reinforcement Learning via Efficient Rollout Scaling

    cs.LG 2026-04 unverdicted novelty 6.0 of 10

    Sol-RL decouples FP4-based candidate exploration from BF16 policy optimization in diffusion RL, delivering up to 4.64x faster convergence with maintained or superior alignment performance on models like FLUX.1 and SD3.5.

  25. From Prior to Pro: Efficient Skill Mastery via Distribution Contractive RL Finetuning

    cs.RO 2026-03 accept novelty 6.0 of 10

    Residual off-policy RL with selective BC regularization and value-guided sampling contracts a pretrained generative robot policy around successful actions, reaching high success on hard long-horizon tasks from pixels ...

  26. SERNF: Sample-Efficient Real-World Dexterous Policy Fine-Tuning via Action-Chunked Critics and Normalizing Flows

    cs.RO 2026-02 unverdicted novelty 6.0 of 10

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  27. SERNF: Sample-Efficient Real-World Dexterous Policy Fine-Tuning via Action-Chunked Critics and Normalizing Flows

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  28. Training Diffusion Policies via Prior-Mapping Co-Evolution

    cs.LG 2025-12 conditional novelty 6.0 of 10

    GoRL outperforms Gaussian and generative RL baselines on continuous control by optimizing a Gaussian latent policy while a separately trained diffusion or flow decoder maps fixed noise to actions.

  29. Reinforcement Fine-Tuning of Flow-Matching Policies for Vision-Language-Action Models

    cs.LG 2025-10 conditional novelty 6.0 of 10

    FPO fine-tunes flow-matching vision-language-action policies with a PPO-style objective that replaces intractable policy ratios with per-sample conditional flow-matching loss differences, reaching 87.2% average succes...

  30. FM-IRL: Flow-Matching for Reward Modeling and Policy Regularization in Reinforcement Learning

    cs.LG 2025-10 conditional novelty 6.0 of 10

    An online imitation-learning method uses a flow-matching teacher's class-conditional loss as a reward and a regularizer to train a simple MLP policy, beating cloning and adversarial-imitation baselines on five of six tasks.

  31. RLMM-Flow: A Flow-based Mobile Manipulation Framework with Latent-Space Reinforcement Learning

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    Steering a frozen flow-based whole-body motion policy in latent space with a warmed-up critic and coarse-to-fine residuals improves mobile manipulation success and safety.

  32. PAVXploreRL: Physical-Action-Visual World Model Reinforcement Learning with Action Exploration

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  33. NavCMPO: Critic-Guided MeanFlow Policy Optimization for Adaptive Navigation

    cs.RO 2026-07 conditional novelty 5.0 of 10

    A two-stage navigation policy using five-step MeanFlow generation, critic-guided trajectory refinement, and PPO fine-tuning reports higher success and lower latency than a matched NavDP baseline.

  34. Driving Intents Amplify Planning-Oriented Reinforcement Learning

    cs.RO 2026-05 unverdicted novelty 5.0 of 10

    DIAL expands continuous-action driving policies via intent-conditioned flow matching and multi-intent GRPO, lifting best-of-N preference scores above human demonstrations for the first time on WOD-E2E.

  35. Preserving Foundational Capabilities in Flow-Matching VLAs through Conservative SFT

    cs.RO 2026-05 unverdicted novelty 5.0 of 10

    ConSFT is a gradient-scaling fine-tuning objective for flow-matching VLAs that bounds parameter disruption via model-confidence weighting, yielding over 20% better capability retention than vanilla SFT on LIBERO and RoboTwin.

  36. FAIL: Flow Matching Adversarial Imitation Learning for Image Generation

    cs.CV 2026-02 conditional novelty 5.0 of 10

    Post-training of flow matching can be framed as adversarial imitation learning, and the proposed FAIL methods improve FLUX's generation quality using 13K expert images without preference pairs.

  37. ReFPO: Reflow Regularization for Flow Matching Policy Gradients

    cs.RO 2026-06 unverdicted novelty 4.0 of 10

    ReFPO adds explicit Reflow regularization to FPO, stabilizing PPO-style training and supporting high-fidelity one-step inference across GridWorld, MuJoCo, and Humanoid tasks.

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