Research map / Reinforcement learning / Imitation learning
Diffusion Model-Augmented Behavioral Cloning
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Proposes Diffusion Model-Augmented Behavioral Cloning (DBC), which adds a diffusion-model loss on expert state-action pairs to the BC loss so the policy learns both conditional p(a|s) and joint p(s,a) signals without environment interaction.
Problem
Behavioral cloning models the conditional p(a|s) and generalizes poorly to unseen states, while joint-probability generative models generalize better but are slow at action retrieval and suffer from manifold overfitting, in environment-free imitation learning.
Approach
Train a DDPM on concatenated expert state-action pairs and use its noise-prediction loss (normalized by the expert diffusion loss, hinged at zero) on policy-predicted actions as an extra learning signal added to the BC loss, so the policy stays efficient at inference while benefiting from joint-distribution guidance.
Key results
- On Maze, DBC achieves 95.4% ± 1.7% success vs. 95.5% for Diffusion Policy and 92.1% for BC; on FetchPick DBC reaches 97.5% vs. 91.6% for BC.
- On AntReach DBC achieves 70.1% success vs. 61.8% for Diffusion Policy and 56.2% for BC.
- Inference speed on Maze: DBC 30.79 episodes/s vs. Diffusion Policy 1.38 episodes/s and Implicit BC 9.92 episodes/s.
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| combine BC loss with diffusion-model loss (ablation) | DBC · FetchPick | success rate: 91.6% ± 5.8% -> 97.5% ± 1.9% | Helped |
| combine BC loss with diffusion-model loss (ablation) | DBC · Maze | success rate: 79.6% ± 9.6% -> 95.4% ± 1.7% | Helped |
| use diffusion model instead of the second-best GAN guide (ablation) | DBC with BC · Maze | success rate: +2.4% | Helped |
| remove expert diffusion-loss normalization (ablation) | DBC · Maze | success rate: 95.4% ± 1.7% -> 94.7% ± 1.9% | Hurt |
| remove expert diffusion-loss normalization (ablation) | DBC · FetchPick | success rate: 96.9% ± 1.7% -> 96.6% ± 1.7% | Hurt |
| set diffusion-loss coefficient λ to 0 (BC only) (ablation) | DBC · FetchPick | success rate: 97.5% -> 91.7% | Hurt |
| set diffusion-loss coefficient λ to 10 (ablation) | DBC · FetchPick | success rate: 51.46% | Hurt |
| train the diffusion model with noise level 0.01 instead of 0 (ablation) | DM-guided policy · spiral maze | success rate: 12% -> 32% | Helped |
| use DM guidance rather than BC alone (ablation) | policy learning on spiral maze · spiral maze | success rate: 85% vs 32% | Hurt |
| use diffusion-model data augmentation for BC (ablation) | BC on Maze · Maze | performance: 2.06% | No clear effect |
| replace conditional policy with joint-probability DM-only policy (ablation) | policy learning on spiral maze · spiral maze | success rate | Hurt |
| use DBC rather than BC | imitation policy · CarRacing | return: 766.4 -> 791.5 | Helped |
Surprising findings
- Diffusion model loss alone (pi_DM) performs poorly on FetchPick (14.2% success), showing that joint-probability guidance alone is insufficient and BC is needed.
- Diffusion Policy underperforms BC on single-mode locomotion tasks (Cheetah, Walker), which the authors attribute to its multimodal design.
Limitations
- Cannot learn from agent (non-expert) trajectories, only expert demonstrations without environment interaction.
- Optimal lambda varies per task and must be tuned so BC and DM losses have similar magnitude.
- Gains on some tasks (Maze, HandRotate, AntReach normalization ablation) are within standard deviation of Diffusion Policy.
Experimental setup
Datasets: maze2d-medium-v2 expert demonstrations FetchPick demonstrations HandRotate expert demonstrations (SAC) Cheetah and Walker demonstrations AntReach demonstrations CarRacing PPO expert demonstrations
Benchmarks: maze2d-medium-v2 (Maze) FetchPick HandRotate Cheetah Walker AntReach CarRacing
Metrics: success rate return episodes per second
Baselines: BC Implicit BC Diffusion Policy
Builds on: behavioral cloning DDPM Implicit BC Diffusion Policy
Closest papers by meaning
- Diffusion Imitation from Observation (NeurIPS 2024 · similarity 0.90)
- Is Behavior Cloning All You Need? Understanding Horizon in Imitation Learning (NeurIPS 2024 · similarity 0.90)
- Imitation Learning from Purified Demonstrations (ICML 2024 · similarity 0.90)
- Latent Diffusion Planning for Imitation Learning (ICML 2025 · similarity 0.90)
- Improving Generative Behavior Cloning via Self-Guidance and Adaptive Chunking (NeurIPS 2025 · similarity 0.89)
- A Smooth Sea Never Made a Skilled SAILOR: Robust Imitation via Learning to Search (NeurIPS 2025 · similarity 0.89)
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