DIFFUSION-POLICYCURRENT2026-05-28

Sample-Efficient Diffusion-based Reinforcement Learning with Critic Guidance

Shutong Ding, Zejia Zhong, Zhongyi Wang, Ke Hu, Bikang Pan, Jingya Wang, Ye Shi

CGPO combines diffusion policies with critic-guided Core ConceptsActionA command the robot sends to its motors, controller, or low-level system. generation to balance Imitation & Reinforcement LearningExplorationTrying different actions to discover useful behavior. and Imitation & Reinforcement LearningExploitationUsing the best-known behavior to get good results. in Imitation & Reinforcement LearningReinforcement Learning (RL)Teaching a robot through trial and error using rewards., achieving faster Core ConceptsPolicyThe rule or model that maps observations or states to actions. convergence and better final performance. This is the first diffusion-based Imitation & Reinforcement LearningReinforcement Learning (RL)Teaching a robot through trial and error using rewards. method demonstrated on real Core ConceptsRobotA physical system with sensors and actuators that can observe the world and take actions. Manipulation & TasksGraspingTaking hold of an object., showing diffusion policies can work in physical Core ConceptsRobotA physical system with sensors and actuators that can observe the world and take actions. tasks with improved Robot LearningSample efficiencyHow quickly a method learns from each example or interaction..

THE PROBLEM

This paper focuses on Modern Robot LearningDiffusion policyA robot policy that generates actions using diffusion-model techniques.. CGPO combines diffusion policies with critic-guided Core ConceptsActionA command the robot sends to its motors, controller, or low-level system. generation to balance Imitation & Reinforcement LearningExplorationTrying different actions to discover useful behavior. and Imitation & Reinforcement LearningExploitationUsing the best-known behavior to get good results. in Imitation & Reinforcement LearningReinforcement Learning (RL)Teaching a robot through trial and error using rewards., achieving faster Core ConceptsPolicyThe rule or model that maps observations or states to actions. convergence and better final performance. This is the first diffusion-based Imitation & Reinforcement LearningReinforcement Learning (RL)Teaching a robot through trial and error using rewards. method demonstrated on real Core ConceptsRobotA physical system with sensors and actuators that can observe the world and take actions. Manipulation & TasksGraspingTaking hold of an object., showing diffusion policies can work in physical Core ConceptsRobotA physical system with sensors and actuators that can observe the world and take actions. tasks with improved Robot LearningSample efficiencyHow quickly a method learns from each example or interaction.. Read the paper by tracking the Core ConceptsTaskThe job the robot is supposed to complete, such as pick-and-place, navigation, or drawer opening. definition, the Core ConceptsRobotA physical system with sensors and actuators that can observe the world and take actions. or data assumptions, and the evidence that supports the claimed improvement.

HOW IT WORKS

1

Task framing

The paper frames the work as Modern Robot LearningDiffusion policyA robot policy that generates actions using diffusion-model techniques.. Start here because it defines what success means and which assumptions the rest of the method inherits.

2

Core method

CGPO combines diffusion policies with critic-guided Core ConceptsActionA command the robot sends to its motors, controller, or low-level system. generation to balance Imitation & Reinforcement LearningExplorationTrying different actions to discover useful behavior. and Imitation & Reinforcement LearningExploitationUsing the best-known behavior to get good results. in Imitation & Reinforcement LearningReinforcement Learning (RL)Teaching a robot through trial and error using rewards., achieving faster Core ConceptsPolicyThe rule or model that maps observations or states to actions. convergence and better final performance. This is the first diffusion-based Imitation & Reinforcement LearningReinforcement Learning (RL)Teaching a robot through trial and error using rewards. method demonstrated on real Core ConceptsRobotA physical system with sensors and actuators that can observe the world and take actions. Manipulation & TasksGraspingTaking hold of an object., showing diffusion policies can work in physical Core ConceptsRobotA physical system with sensors and actuators that can observe the world and take actions. tasks with improved Robot LearningSample efficiencyHow quickly a method learns from each example or interaction.. When reading the method section, identify the inputs, the learned or engineered representation, and the Core ConceptsActionA command the robot sends to its motors, controller, or low-level system. or prediction produced by the system.

3

Data and supervision

For robotics work, the data story is part of the method: check whether the system depends on Imitation & Reinforcement LearningTeleoperation (teleop)A human remotely controlling the robot, often to collect demonstrations., Simulation & Sim-to-RealSimulationA virtual environment where robots can be trained or tested., internet video, human labels, or Core ConceptsRobotA physical system with sensors and actuators that can observe the world and take actions. rollouts.

4

Evaluation evidence

The paper should be judged through its Simulation & Sim-to-RealEvaluationMeasuring how well a robot system performs. protocol: what data is used, what Core ConceptsRobotA physical system with sensors and actuators that can observe the world and take actions. or simulator is tested, and which Evaluation & ResearchBaselineA reference method used for comparison. comparisons support the claim. Look for the gap between the headline result and the Simulation & Sim-to-RealDeploymentPutting the trained system on a real robot. setting you would actually care about.

FIGURES

KEY RESULTS

Main contributionConceptual contribution

CGPO combines diffusion policies with critic-guided Core ConceptsActionA command the robot sends to its motors, controller, or low-level system. generation to balance Imitation & Reinforcement LearningExplorationTrying different actions to discover useful behavior. and Imitation & Reinforcement LearningExploitationUsing the best-known behavior to get good results. in Imitation & Reinforcement LearningReinforcement Learning (RL)Teaching a robot through trial and error using rewards., achieving faster Core ConceptsPolicyThe rule or model that maps observations or states to actions. convergence and better final performance. This is the first diffusion-based Imitation & Reinforcement LearningReinforcement Learning (RL)Teaching a robot through trial and error using rewards. method demonstrated on real Core ConceptsRobotA physical system with sensors and actuators that can observe the world and take actions. Manipulation & TasksGraspingTaking hold of an object., showing diffusion policies can work in physical Core ConceptsRobotA physical system with sensors and actuators that can observe the world and take actions. tasks with improved Robot LearningSample efficiencyHow quickly a method learns from each example or interaction..

WHY DEVELOPERS SHOULD CARE

CGPO combines diffusion policies with critic-guided Core ConceptsActionA command the robot sends to its motors, controller, or low-level system. generation to balance Imitation & Reinforcement LearningExplorationTrying different actions to discover useful behavior. and Imitation & Reinforcement LearningExploitationUsing the best-known behavior to get good results. in Imitation & Reinforcement LearningReinforcement Learning (RL)Teaching a robot through trial and error using rewards., achieving faster Core ConceptsPolicyThe rule or model that maps observations or states to actions. convergence and better final performance. This is the first diffusion-based Imitation & Reinforcement LearningReinforcement Learning (RL)Teaching a robot through trial and error using rewards. method demonstrated on real Core ConceptsRobotA physical system with sensors and actuators that can observe the world and take actions. Manipulation & TasksGraspingTaking hold of an object., showing diffusion policies can work in physical Core ConceptsRobotA physical system with sensors and actuators that can observe the world and take actions. tasks with improved Robot LearningSample efficiencyHow quickly a method learns from each example or interaction..

LIMITATIONS

The main limitation to check is whether the claimed behavior holds outside the paper's reported setup. That means testing across different Core ConceptsRobotA physical system with sensors and actuators that can observe the world and take actions. embodiments, scenes, objects, and data distributions.

WHAT COMES NEXT

The practical next step is independent reproduction with clear baselines, ablations, and stress tests. For a developer, the useful follow-up is to map the paper's Modern Robot LearningDiffusion policyA robot policy that generates actions using diffusion-model techniques. assumptions onto a concrete Core ConceptsRobotA physical system with sensors and actuators that can observe the world and take actions. stack, then test the smallest version of the method that could run end to end.

RELATED PAPERS