feat(policies): add VLA-JEPA (#3568)

* first commit

* feat(policies): add VLA-JEPA

* feat(policies): add VLA-JEPA

* support vla_jepa

* (feat)policies: add VLA-JEPA

* linting

* adding deps to pyproject.toml

* updating uv lock

* adding guards to avoid needing transformers and diffusers for type checking and basic tests

* fixing action and state dim

* fix warnings with qwen processor kwargs

* fixing wm_loss not propagating

* adjusting obs steps, tublets size to match original implementation

* some more fixes to be closer to the original implem

* adding more tests to ensure good coverage

* align VLA-JEPA architecture with original checkpoint

- Remove stale `action_num_heads` / `action_attention_head_dim` config fields;
  DiT head dimensions are now always derived from the preset (DiT-B/L/test).
- Add `num_target_vision_tokens` and `action_max_seq_len` config fields required
  by the action head's future-token embedding and positional embedding tables.
- Fix default `qwen_model_name` to 2B (matches all released checkpoints).
- Rename `ActionEncoder` attrs w1/w2/w3 → layer1/layer2/layer3 to match
  checkpoint key names; replace `nn.Sequential` decoder/state-encoder with
  `_MLP2` (layer1/layer2 naming).
- Fix `VLAJEPAActionHead` to size ActionEncoder and StateEncoder at `inner_dim`
  (DiT input width) rather than `action_hidden_size` (DiT output width).
- Rename `DiT.blocks` → `transformer_blocks` and `attn` → `attn1` to match
  checkpoint; add alternating cross/self attention (even blocks cross-attend to
  Qwen context, odd blocks self-attend).
- Add `DiT-test` preset for unit tests.
- Rewrite `ActionConditionedVideoPredictor` with explicit ViT-style blocks
  (`_PredictorBlock` with fused qkv) to match checkpoint structure; rename
  `encoder`/`norm`/`proj` → `predictor_blocks`/`predictor_norm`/`predictor_proj`.

* propagate action_is_pad masking through VLA-JEPA policy pipeline

Pass the `action_is_pad` tensor from the batch through to the action head
so padded timesteps are excluded from the flow-matching loss.

* update VLA-JEPA tests for arch changes and action_is_pad

- Switch conftest to use `action_model_type="DiT-test"` now that
  `action_num_heads` / `action_attention_head_dim` have been removed.
- Add action_head tests covering fully-padded loss (zero) and equivalence
  of action_is_pad=None vs all-zeros mask.
- Remove obsolete `test_native_to_lerobot_wm_only` test.

* add VLA-JEPA documentation

Covers architecture overview, pretrained checkpoints, config reference,
training/eval commands for LIBERO-10, and guidance on fine-tuning for
single-camera datasets.

* add one-shot script to convert ginwind/VLA-JEPA checkpoints to safetensors (will remove once migrated)

* make default params more aligned with paper and pretrained models
- adding possibility of freezing qwen backbone and world model
- added tests for weight loading

* trying out to re-init the action head to avoid pretraining dimension mismatch

* allow different state dim and action dim

* removing missleading future_action_window_size to just use chunk_size

* lots of changes to make existing weights work, need to massively refactor the pre and post processing

* refactoring into using pre and post processor

* pre-commit cleanup

* fixing doc defaults args

Signed-off-by: Maxime Ellerbach <maxime@ellerbach.net>

* adressing dtype zeros issue

* adding guard for diffusers

* fixing training and exal examples

* trying to close success rate gap

* fix qwen norm layer output libero eval is now as expected

* adding instructions for different embodiement + fixing some tests

* smol fix to avoid having default CPU device when training

* fixing misconception about multiview / singleview handling

* removing conversion script

* adding licences

* adding .mdx docs and shortening polivy_vla_jepa_README.md

* removing useless pre-processor

* cleanup

* removing swish in favor of silu

* adding configuration gripper index and threshold

* fixing simlink

---------

Signed-off-by: Maxime Ellerbach <maxime@ellerbach.net>
Co-authored-by: ginwind <ginwind@mail.ustc.edu.cn>
This commit is contained in:
Maxime Ellerbach
2026-06-04 19:22:51 +02:00
committed by GitHub
parent d1b1c5c8cf
commit 2e9cd87bbd
19 changed files with 3283 additions and 1 deletions

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title: π₀.₅ (Pi05)
- local: molmoact2
title: MolmoAct2
- local: vla_jepa
title: VLA-JEPA
- local: eo1
title: EO-1
- local: groot

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# VLA-JEPA
This repository contains the LeRobot port of **VLA-JEPA**, a Vision-Language-Action model that combines a Qwen3-VL language backbone with a self-supervised video world model (V-JEPA2) and a flow-matching DiT action head.
Converted from [ginwind/VLA-JEPA](https://huggingface.co/ginwind/VLA-JEPA).
---
## Architecture Overview
| Component | Module | Role |
| ----------------------- | --------------------------------- | ------------------------------------------------------- |
| **Qwen3-VL backbone** | `Qwen3VLInterface` | Fuses images + language instruction into context tokens |
| **DiT-B action head** | `VLAJEPAActionHead` | Flow-matching diffusion over the action chunk |
| **V-JEPA2 world model** | `ActionConditionedVideoPredictor` | Self-supervised video prediction loss (training only) |
At inference time only the Qwen backbone and action head are used; the world model is not needed.
---
## Citation
```bibtex
@misc{sun2026vlajepaenhancingvisionlanguageactionmodel,
title = {VLA-JEPA: Enhancing Vision-Language-Action Model with Latent World Model},
author = {Jingwen Sun and Wenyao Zhang and Zekun Qi and Shaojie Ren and Zezhi Liu and Hanxin Zhu and Guangzhong Sun and Xin Jin and Zhibo Chen},
year = {2026},
eprint = {2602.10098},
archivePrefix = {arXiv},
primaryClass = {cs.RO},
url = {https://arxiv.org/abs/2602.10098},
}
```
---
## License
Weights are distributed under the license terms of the original [ginwind/VLA-JEPA](https://huggingface.co/ginwind/VLA-JEPA) repository (**Apache 2.0 License**). The LeRobot integration code follows the **Apache 2.0 License**.

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# VLA-JEPA
This is the LeRobot port of **VLA-JEPA**, a Vision-Language-Action model that combines a Qwen3-VL language backbone with a self-supervised video world model (V-JEPA2) and a flow-matching DiT action head.
---
## Architecture Overview
VLA-JEPA has three main components:
| Component | Module | Role |
| ----------------------- | --------------------------------- | ------------------------------------------------------- |
| **Qwen3-VL backbone** | `Qwen3VLInterface` | Fuses images + language instruction into context tokens |
| **DiT-B action head** | `VLAJEPAActionHead` | Flow-matching diffusion over the action chunk |
| **V-JEPA2 world model** | `ActionConditionedVideoPredictor` | Self-supervised video prediction loss (training only) |
### Data flow
**Training:**
1. A video clip of `num_video_frames` frames is encoded by V-JEPA2 into per-frame patch tokens.
2. The Qwen3-VL backbone processes multi-view images + the task instruction and produces a sequence of context tokens that includes special action tokens (for world model conditioning) and embodied tokens.
3. The action head receives those context tokens as cross-attention keys/values and predicts a denoised action chunk via flow matching.
4. The world model predictor uses the action tokens extracted from Qwen to predict future V-JEPA2 frame embeddings; a regression loss on those predictions is added to the action loss.
**Inference:**
Only Qwen + the action head are used. The world model is not needed at inference time.
### Action head details
Available presets via `action_model_type`:
| Preset | Hidden dim | Heads | Head dim |
| ------- | ---------- | ----- | -------- |
| `DiT-B` | 768 | 12 | 64 |
| `DiT-L` | 1536 | 32 | 48 |
### World model details
The video predictor is a ViT-style transformer (`ActionConditionedVideoPredictor`) that takes:
- **Frame tokens**: V-JEPA2 patch embeddings projected to `predictor_embed_dim`
- **Action tokens**: Qwen action token embeddings projected to `predictor_embed_dim`
It uses block-causal attention so each temporal step can attend to all previous steps. The predictor's input `embed_dim` equals `num_views × video_encoder_hidden_size` (e.g. 2 views × 1024 = 2048 for the pretrained checkpoints).
---
## Pretrained Checkpoints
Three checkpoints are available directly inside the LeRobot org here: [`lerobot/VLA-JEPA`](https://huggingface.co/collections/lerobot/vla-jepa), converted from [ginwind/VLA-JEPA](https://huggingface.co/ginwind/VLA-JEPA):
| Checkpoint | Dataset | Cameras | World model | Action dim |
| ----------------------------- | ----------------- | ----------------------- | ----------- | ---------- |
| `lerobot/VLA-JEPA-LIBERO` | LIBERO-10 | 2 (agentview + wrist) | Enabled | 7 |
| `lerobot/VLA-JEPA-Pretrain` | DROID 1.0.1 | 2 (exterior left views) | Enabled | 7 |
| `lerobot/VLA-JEPA-SimplerEnv` | OXE Bridge / RT-1 | 1 (view duplicated ×2) | Enabled | 7 |
All checkpoints use `Qwen/Qwen3-VL-2B-Instruct` as the language backbone.
---
## Configuration
Key parameters in `VLAJEPAConfig`:
| Parameter | Default | Description |
| ------------------------- | ------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `chunk_size` | 7 | Number of actions predicted per inference call |
| `n_action_steps` | 7 | Steps executed from the predicted chunk before re-planning |
| `num_video_frames` | 8 | Video clip length fed to the world model |
| `enable_world_model` | `True` | Whether to load and train the V-JEPA2 predictor |
| `world_model_loss_weight` | 0.1 | Weight of the JEPA prediction loss relative to the action loss |
| `num_inference_timesteps` | 4 | Euler integration steps for action denoising |
| `freeze_qwen` | `False` | Freeze the Qwen3-VL backbone and only train the action head |
| `reinit_modules` | `None` | Key prefixes allowed to be randomly re-initialised on load (for cross-embodiment transfer, see [Fine-tuning on a different embodiment](#fine-tuning-on-a-different-embodiment)) |
| `gripper_dim` | 6 | Index of the gripper dimension in the action vector (e.g. 6 for a 7-DoF arm with gripper as the last joint) |
| `gripper_threshold` | 0.5 | Threshold used by `pre_snap_gripper_action` and `binarize_gripper_action` to binarize the gripper dimension |
| `pre_snap_gripper_action` | `True` | Snap the gripper dim to {0, 1} before unnormalization. Set to `False` for robots without a binary gripper |
| `binarize_gripper_action` | `True` | Binarize the gripper dim to {-1, 1} after unnormalization. Set to `False` for robots without a binary gripper |
---
## Training
Number of training steps may vary based on dataset size and compute budget. The original paper pretrained for 50k on ssv2 + droid jointly, then additional 30k steps for LIBERO, but fewer steps may still yield good performance when fine-tuning from the provided pretrained checkpoints.
### Full training from scratch
```bash
lerobot-train \
policy.type=vla_jepa \
policy.repo_id=your_org/your_repo \
dataset.repo_id=your_org/your_dataset
```
### Fine-tuning from a pretrained checkpoint
```bash
lerobot-train \
--policy.path=lerobot/VLA-JEPA-Pretrain \
--policy.repo_id=your_org/your_repo \
--dataset.repo_id=your_org/your_dataset
```
If you want to freeze the Qwen backbone and only train the action head, set `policy.freeze_qwen=True`:
```bash
lerobot-train \
--policy.path=lerobot/VLA-JEPA-Pretrain \
--policy.repo_id=your_org/your_repo \
--policy.freeze_qwen=true \
--dataset.repo_id=your_org/your_dataset
```
### Fine-tuning on a different embodiment
When the target robot has a different action or state dimensionality than the pretrained checkpoint, the input/output projection layers of the action head will have mismatched shapes and cannot be loaded directly. `reinit_modules` lets you list the key prefixes that are allowed to mismatch — those layers are randomly re-initialised while every other weight is reused from the checkpoint. Any shape mismatch outside the listed prefixes raises an error.
The layers that depend on `action_dim` and `state_dim` are:
| Layer | Key prefix |
| ----------------------------------------- | ----------------------------------- |
| Action encoder (action_dim → inner_dim) | `model.action_model.action_encoder` |
| Action decoder (hidden_size → action_dim) | `model.action_model.action_decoder` |
| State encoder (state_dim → inner_dim) | `model.action_model.state_encoder` |
```bash
lerobot-train \
--policy.path=lerobot/VLA-JEPA-Pretrain \
--policy.repo_id=your_org/your_repo \
--policy.freeze_qwen=true \
--policy.reinit_modules='["model.action_model.action_encoder", "model.action_model.action_decoder", "model.action_model.state_encoder"]' \
--dataset.repo_id=your_org/your_dataset
```
If your robot has no proprioceptive state, omit `model.action_model.state_encoder` from the list.
### Reproducing the LIBERO results
**Training on LIBERO:**
starts the training from the Pretrain checkpoint, trains for 30k steps on the LIBERO dataset.
Original paper mentions training across 8 GPUs with a batch size of 32, meaning global batch size of 256.
```bash
lerobot-train \
--policy.path=lerobot/VLA-JEPA-Pretrain \
--policy.repo_id=your_org/your_repo \
--dataset.repo_id=HuggingFaceVLA/libero \
--steps=30000
```
**Evaluating the pretrained LIBERO-10 checkpoint:**
```bash
lerobot-eval \
--policy.path=lerobot/VLA-JEPA-LIBERO \
--env.type=libero \
--env.task=libero_spatial,libero_object,libero_goal,libero_10 \
--eval.n_episodes=10 \
--eval.batch_size=5
```
To evaluate a subset of tasks only:
```bash
lerobot-eval \
--policy.path=lerobot/VLA-JEPA-LIBERO \
--env.type=libero \
--env.task=libero_10 \
--env.task_ids='[0,1,2]' \
--eval.n_episodes=10 \
--eval.batch_size=5
```
**Expected results:**
| Suite | Episodes | Successes | Success Rate |
| -------------- | -------- | --------- | ------------ |
| libero_spatial | 100 | 93 | **95.0%** |
| libero_object | 100 | 100 | **100.0%** |
| libero_goal | 100 | 98 | **98.0%** |
| libero_10 | 100 | 96 | **93.0%** |
| **Overall** | **400** | **387** | **96.5%** |
---
## Fine-tuning on datasets with a different number of cameras
The pretrained world model predictor was trained with `embed_dim = jepa_tubelet_size × 1024` (default `jepa_tubelet_size=2`).
**Default behaviour — view padding / trimming (no action required)**
When fine-tuning from `VLA-JEPA-Pretrain` the model automatically adjusts the number of views fed to the world model to match `jepa_tubelet_size`:
- **Single-view datasets (e.g. BridgeV2):** the single-view latent is duplicated to produce a two-view world-model input, preserving the JEPA self-supervised signal without any weight mismatch.
- **>2-view datasets (e.g. DROID with 3 views):** all views are passed to the Qwen backbone (for richer context), but only the first `jepa_tubelet_size` views (one wrist + one third-person, following the configured view order) are used for the world model.
**Option 1 — Disable the world model**
Set `enable_world_model=False` to skip the JEPA loss entirely. Only the Qwen backbone and action head are loaded and trained. This is sufficient for good action performance.
```bash
lerobot-train \
--policy.path=lerobot/VLA-JEPA-Pretrain \
--policy.enable_world_model=false \
--policy.repo_id=your_org/your_repo \
--dataset.repo_id=your_org/single_camera_dataset
```
**Option 2 — Reinitialize the predictor input projection**
If you want to change `jepa_tubelet_size` to a value other than 2, load the checkpoint with `strict=False` and reinitialize `model.video_predictor.predictor_embed` for the new `embed_dim`. All other predictor block weights (attention, MLP, norm, output projection) are camera-count-agnostic and can be reused from the pretrained checkpoint.
---
## Citation
```bibtex
@misc{sun2026vlajepaenhancingvisionlanguageactionmodel,
title = {VLA-JEPA: Enhancing Vision-Language-Action Model with Latent World Model},
author = {Jingwen Sun and Wenyao Zhang and Zekun Qi and Shaojie Ren and Zezhi Liu and Hanxin Zhu and Guangzhong Sun and Xin Jin and Zhibo Chen},
year = {2026},
eprint = {2602.10098},
archivePrefix = {arXiv},
primaryClass = {cs.RO},
url = {https://arxiv.org/abs/2602.10098},
}
```
---
## License
Weights are distributed under the license terms of the original [ginwind/VLA-JEPA](https://huggingface.co/ginwind/VLA-JEPA) repository (**Apache 2.0 License**). The LeRobot integration code follows the **Apache 2.0 License**.