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arXiv · 2606.22303

FlowDPG: Deterministic Policy Gradient on Flow Matching Policies for Real-World Manipulation

Kexin Shi·Junyao Shi·Poorvi Hebbar·Zhuolun Zhao·Tarun Amarnath·Yifan Su·Shikhar Bahl·Deepak Pathak
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Abstract

Real-world reinforcement learning for robotic manipulation remains challenging, and this difficulty is amplified for flow matching policies: applying policy gradient methods to these policies is fundamentally limited by the need to backpropagate through time(BPTT) along the multi-step ODE that maps noise to actions, which is computationally prohibitive and numerically fragile. We propose FlowDPG, a DDPG-style method specifically designed for flow matching policies that distills the critic gradient into the velocity field at training time, bypassing BPTT entirely. Intuitively, FlowDPG combines two complementary vectors: the demonstration-driven velocity that keeps the action feasible, and the critic-driven correction that steers it toward higher value. Our contributions are threefold: (1) a BPTT-free distillation framework that enables stable DDPG-style policy improvement on flow matching policies, (2) a formal connection between the FlowDPG update direction and vanilla Deterministic Policy Gradient via three explicit approximations, and (3) real-world validation on a long-horizon, multi-stage, dual-arm AirPods assembly task, where FlowDPG attains a 92% end-to-end success rate, substantially outperforming recent RL methods spanning value-conditioning, auxiliary-module adaptation, and adjoint-based critic-gradient approaches. Videos and more results are provided on the project page https://flowdpg.github.io.

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Kexin Shi, Junyao Shi, Poorvi Hebbar, Zhuolun Zhao, Tarun Amarnath, Yifan Su, Shikhar Bahl, Deepak Pathak. 2026-06-21. FlowDPG: Deterministic Policy Gradient on Flow Matching Policies for Real-World Manipulation. https://arxiv.org/abs/2606.22303

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