docs: update X-VLA training strategies/commands (#2611)

This commit is contained in:
Jade Choghari
2025-12-09 19:08:09 +01:00
committed by GitHub
parent 7f40b3bf82
commit cb920235c4
+40 -82
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@@ -24,7 +24,7 @@ Built from pure Transformer encoders, X-VLA scales naturally with model size and
<img
src="https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/lerobot/xvla-architecture2.png"
alt="XVLA Architecture 2"
style="width: 32%; max-width: 450px; height: auto;"
style="width: 60%; height: auto;"
/>
</p>
@@ -120,7 +120,7 @@ Adapted for Google Robot platforms.
### Recommended Training Configuration
When fine-tuning X-VLA for a new embodiment or task, we recommend the following freezing strategy:
When fine-tuning X-VLA for a new embodiment or task, we recommend not freezing the VLM, and also setting the `policy.dtype=bfloat16` to not hit OOM errors.
```bash
lerobot-train \
@@ -129,25 +129,26 @@ lerobot-train \
--job_name=xvla_training \
--policy.path="lerobot/xvla-base" \
--policy.repo_id="HF_USER/xvla-your-robot" \
--policy.dtype=bfloat16 \
--steps=3000 \
--policy.device=cuda \
--policy.freeze_vision_encoder=True \
--policy.freeze_language_encoder=True \
--policy.train_policy_transformer=True \
--policy.train_soft_prompts=True \
--policy.freeze_vision_encoder=false \
--policy.freeze_language_encoder=false \
--policy.train_policy_transformer=true \
--policy.train_soft_prompts=true \
--policy.action_mode=YOUR_ACTION_MODE
```
### Training Parameters Explained
| Parameter | Default | Description |
| -------------------------- | ------- | ---------------------------------------- |
| `freeze_vision_encoder` | `True` | Freeze the VLM vision encoder weights |
| `freeze_language_encoder` | `True` | Freeze the VLM language encoder weights |
| `train_policy_transformer` | `True` | Allow policy transformer layers to train |
| `train_soft_prompts` | `True` | Allow soft prompts to train |
| Parameter | Default | Description |
| -------------------------- | ------- | ---------------------------------------------- |
| `freeze_vision_encoder` | `false` | Do not freeze the VLM vision encoder weights |
| `freeze_language_encoder` | `false` | Do not freeze the VLM language encoder weights |
| `train_policy_transformer` | `true` | Allow policy transformer layers to train |
| `train_soft_prompts` | `true` | Allow soft prompts to train |
**💡 Best Practice**: For Phase II adaptation to new embodiments, freeze the VLM encoders and only train the policy transformer and soft prompts. This provides excellent sample efficiency with minimal compute.
**💡 Best Practice**: For Phase II adaptation to new embodiments, do not freeze the VLM encoders and also train the policy transformer and soft prompts.
### Example: Training on Bimanual Robot
@@ -157,14 +158,15 @@ lerobot-train \
--output_dir=./outputs/xvla_bimanual \
--job_name=xvla_so101_training \
--policy.path="lerobot/xvla-base" \
--policy.dtype=bfloat16 \
--policy.repo_id="YOUR_USERNAME/xvla-biso101" \
--steps=3000 \
--policy.device=cuda \
--policy.action_mode=so101_bimanual \
--policy.freeze_vision_encoder=True \
--policy.freeze_language_encoder=True \
--policy.train_policy_transformer=True \
--policy.train_soft_prompts=True
--policy.freeze_vision_encoder=false \
--policy.freeze_language_encoder=false \
--policy.train_policy_transformer=true \
--policy.train_soft_prompts=true
```
💡 **Best Performance:** If you have sufficient computational resources and want to achieve best X-VLA finetuning performance, you should follow the official finetuning strategy:
@@ -172,71 +174,7 @@ lerobot-train \
**🔥 Full-finetune all components with a custom learning-rate scheme**
To ensure stable optimization, the Vision-Language Model (VLM) must be trained with only 1/10 of the base learning rate, while all other components use the full LR.
This LR ratio is crucial for achieving strong and stable finetuning performance.
To enable this behavior, you must:
1. Implement a custom optimizer and register it in your training config
```
from dataclasses import dataclass, asdict
from lerobot.optim.optimizers import OptimizerConfig
import torch
@OptimizerConfig.register_subclass("xvla-adamw")
@dataclass
class XVLAAdamW(OptimizerConfig):
lr: float = 1e-4
betas: tuple[float, float] = (0.9, 0.99)
eps: float = 1e-8
weight_decay: float = 0.0
grad_clip_norm: float = 10.0
def build(self, params: dict) -> torch.optim.Optimizer:
"""
Expect `named_parameters()` as input.
Apply lr = lr / 10 for all VLM-related parameters.
"""
assert isinstance(params, dict), \
"Custom LR optimizer requires `named_parameters()` as inputs."
kwargs = asdict(self)
kwargs.pop("grad_clip_norm")
vlm_group, other_group = [], []
for name, p in params.items():
if not p.requires_grad:
continue
if "vlm" in name.lower():
vlm_group.append(p)
else:
other_group.append(p)
param_groups = [
{"params": vlm_group, "lr": self.lr * 0.1, "weight_decay": self.weight_decay * 0.1},
{"params": other_group, "lr": self.lr, "weight_decay": self.weight_decay},
]
return torch.optim.AdamW(param_groups, **kwargs)
```
2. Modify X-VLAs get_optim_params to return named parameters
Replace:
```
def get_optim_params(self) -> dict:
"""Return only trainable parameters for optimization."""
return filter(lambda p: p.requires_grad, self.parameters())
```
with:
```
def get_optim_params(self):
"""Return trainable named parameters."""
return filter(lambda kv: kv[1].requires_grad, self.named_parameters())
```
This ensures the optimizer receives a dict of named parameters, allowing it to correctly detect VLM modules and apply the 1/10 LR rule.
This LR ratio is crucial for achieving strong and stable finetuning performance. This is already done for you by default.
❕Note
Completely matching the official reported performance may require an additional warm-up LR schedule for soft-prompts, which can bring minor improvements.
@@ -326,6 +264,26 @@ domain_id = 3
The domain_id is automatically added to observations by the `XVLAAddDomainIdProcessorStep` in the preprocessing pipeline.
The `lerobot/xvla-base` model has been trained on the following domain IDs. It is recommended to choose one that most resembles your robot/configuration:
#### Fine-tuning Datasets
| Dataset Name | Domain ID |
| ---------------- | --------- |
| Bridge | 0 |
| RT1 | 1 |
| Calvin | 2 |
| libero | 3 |
| widowx-air | 4 |
| AIR-AGILEX-HQ | 5 |
| robotwin2_abs_ee | 6 |
| robotwin2_clean | 6 |
| robocasa-human | 7 |
| VLABench | 8 |
| AGIBOT-challenge | 9 |
| AIR-AGILEX | 10 |
| AIRBOT | 18 |
### 3. Processor Steps
X-VLA requires specific preprocessing and postprocessing steps for proper operation.