imagewam-ur3-3task

ImageWAM-FLUX.2-4B — real-world UR3, three tasks jointly

Real-world fine-tune of ImageWAM (FLUX.2 [klein] base 4B editing DiT + ActionDiT action expert) on a bimanual dual-arm UR3, trained jointly on three tasks:

300 episodes / 99,677 frames total, 15 fps. Initialized from yuyangalin/ImageWAM-FLUX.2-4B-InternData-A1-EE (InternData-A1 pretrain, step 60k) — loaded with 0 missing / 0 unexpected keys.

Files

Each .pt holds only the trained parts (mot ≈ 8.2 B params + proprio_encoder), ~9.0 GB. FLUX.2 klein-base-4B base weights and autoencoder must be prepared separately.

Recipe

lr 2.5e-5 cosine w/ 5% warmup, AdamW(0.9, 0.95), wd 1e-2, grad-clip 1.0, bf16, DeepSpeed ZeRO-1, global batch 192 (8/GPU × 6 GPUs × 4 grad-accum), 10,000 steps (~19 epochs), ~9.6 h on 6×H100. num_frames=17, action_video_freq_ratio=1 → 16-step action horizon, endpoint_frames_only=true. 14-dim UR3 joint action/state is padded to the pretrain's 16D space at dims 7 and 15 (ee16); nothing is converted to end-effector poses.

Inference — three things that will bite you

1. Mosaic is 288×256 (compact_288x256): camera_top 192×256 on top, the two wrists 96×128 side-by-side below, order fixed [top, left, right], pixels normalized to (−1, 1).
2. Actions come back 16D. Un-pad to 14D — concat(x[..., 0:7], x[..., 8:15]) — before sending to the controller.
3. Use ur3_3task_ee16_dataset_stats.json for denormalization; these stats are computed on this dataset, not the pretrain's.

Checkpoint selection — read this before picking one

Train loss_action fell 21× over the run (0.0917 → 0.0043), but held-out action_l1 barely moved: by thirds of training 0.0344 → 0.0325 → 0.0306, with a regression slope of only −0.00053 per 1k steps (t = −2.14) across 20 evals. Per-eval noise (sd 0.0034 over 32 clips) is larger than the gap between any two of the checkpoints above, so these five are statistically indistinguishable and the ranking should not be trusted. Step 4,000's 0.0281 sits between 0.0323 and 0.0362 at the adjacent evals.

Checkpoints exist only at multiples of 1,000 (save_every: 1000); evals ran every 500, so some of the best-scoring evals (e.g. 0.0248 at step 7,500) have no corresponding checkpoint.

Offline action_l1 has not been validated against real-robot success rate on this setup. Select by real-robot success, not by this metric.

Note also that the last 3,000 steps bought nothing measurable — 7k would have sufficed.

Citation

Built on ImageWAM:

@misc{zhang2026imagewam,
      title={ImageWAM: Do World Action Models Really Need Video Generation, or Just Image Editing?},
      author={Yuyang Zhang and Wenyao Zhang and Zekun Qi and He Zhang and Haitao Lin and Jingbo Zhang and Yao Mu and Xiaokang Yang and Wenjun Zeng and Xin Jin},
      year={2026},
      eprint={2606.19531},
      archivePrefix={arXiv},
      url={https://arxiv.org/abs/2606.19531},
}