EVA: Aligning Video World Models with Executable Robot Actions via Inverse Dynamics Rewards

Table of Contents

• Overview
• Release Progress
• Model Download
• Installation
• Inference
• Training
  • Supervised Fine-Tuning on Robotwin
  • Inverse Dynamics Model Training
  • GRPO-Based Post-Training
• Acknowledgments
• Citation

💫 Overview

EVA is a post-training framework for aligning video world models with physically executable robot actions.

Recent work explores video generative models as visual planners for robotic manipulation. However, these models often produce rollouts that violate rigid-body and kinematic consistency, producing unstable or infeasible control commands when decoded by an inverse dynamics model. We refer to this mismatch between visual generation and physically executable control as the executability gap.

We introduce Executable Video Alignment (EVA), a reinforcement-learning post-training framework for aligning video world models. EVA trains an inverse dynamics model on real robot trajectories and repurposes it as a reward model that evaluates generated videos through the action sequences they induce, encouraging smooth motions measured by velocity, acceleration, and jerk while penalizing actions that violate embodiment constraints.

Release Progress

• Inference code
• Video world model checkpoint
• Supervised fine-tuning code
• RL post-training code

---

Model Download

EVA Checkpoint

You can download the EVA checkpoint fine-tuned on RoboTwin with:

huggingface-cli download RobbinWang123/EVA \
  --include "eva_i2v_14B.ckpt" \
  --local-dir ./data/ckpts

You can also download the IDM checkpoint used for inverse-dynamics reward modeling with:

huggingface-cli download RobbinWang123/EVA \
  --include "IDM_singleview.pt" \
  --local-dir ./data/ckpts

Wan 2.1 Pretrained Checkpoint

This codebase uses the Wan 2.1 Image-to-Video 14B model as the base model.

Please follow the official Wan release for the latest instructions:

• https://github.com/Wan-Video/Wan2.1

Example download command:

huggingface-cli download Wan-AI/Wan2.1-I2V-14B-480P \
  --local-dir ./data/ckpts/Wan2.1-I2V-14B-480P

The downloaded directory should include the diffusion model, VAE, text encoder, and CLIP encoder.

Installation

# Clone the repository
git clone https://github.com/RobbinW/EVA.git
cd EVA

# Create conda environment
conda create -n eva python=3.10
conda activate eva

# Install dependencies
pip install -r requirements.txt

# Install Flash Attention
# This may take several minutes to compile
pip install flash-attn --no-build-isolation

Inference

Example Inference Command

CUDA_VISIBLE_DEVICES=0 python -m main \
  +name=demo_infer \
  experiment=exp_inference \
  algorithm=wan_i2v \
  dataset=image_csv \
  dataset.data_root=data/test_images \
  dataset.metadata_path=metadata.csv \
  dataset.height=480 \
  dataset.width=640 \
  algorithm.model.tuned_ckpt_path=/path/to/EVA/data/ckpts/eva_i2v_14B.ckpt \
  algorithm.hist_guidance=1.5 \
  algorithm.lang_guidance=2.5 \
  algorithm.logging.video_type=single

Generated videos will be saved to:

outputs/<date>/<time>/videos/

Notes

• algorithm.model.tuned_ckpt_path should point to the EVA fine-tuned checkpoint.
• The Wan base checkpoint paths can be set in configurations/algorithm/wan_i2v.yaml.
• algorithm.hist_guidance and algorithm.lang_guidance control the classifier-free guidance (CFG) scales for image (history) and language conditioning during inference.

Training

Supervised Fine-Tuning on Robotwin

We recommend placing RoboTwin and EVA under the same workspace:

$WORKSPACE
├── RoboTwin
│   └── data
└── EVA
    └── data/ckpts

Before SFT, first prepare RoboTwin data by following the official RoboTwin installation and data collection documentation:

• RoboTwin installation doc: https://robotwin-platform.github.io/doc/usage/robotwin-install.html
• RoboTwin usage doc: https://robotwin-platform.github.io/doc/usage/index.html

In our setting, we move the camera backward to obtain a wider view of the workspace. You may refer to https://github.com/thu-ml/vidar-robotwin for an example of modifying the embodiment camera position.

After collection, your dataset should live under:

$WORKSPACE/RoboTwin/data

Then switch back to $WORKSPACE/EVA. The commands below assume your current directory is this repository root.

1. Generate robotwin_videos.csv from RoboTwin videos and instruction files:

python datasets/generate_robotwin_csv.py \
  --root-dir $WORKSPACE/RoboTwin/data \
  --output-csv $WORKSPACE/RoboTwin/data/robotwin_videos.csv

2. Cache the prompt embeddings referenced by robotwin_videos.csv:

CUDA_VISIBLE_DEVICES=0 python main.py \
  +name=process_robotwin_embeds \
  experiment=process_data \
  dataset=robotwin \
  dataset.data_root=$WORKSPACE/RoboTwin/data \
  dataset.metadata_path=robotwin_videos.csv \
  algorithm=wan_i2v \
  algorithm.text_encoder.ckpt_path=./data/ckpts/Wan2.1-I2V-14B-480P/models_t5_umt5-xxl-enc-bf16.pth \
  experiment.tasks=[cache_prompt_embed] \
  experiment.new_data_root=$WORKSPACE/RoboTwin/data \
  experiment.cache_prompt_embed.batch_size=16

This command saves prompt embeddings as *.pt files alongside each RoboTwin video, and updates robotwin_videos.csv in place with the prompt_embed_path column used by training.

3. Download the released Large Video Planner backbone checkpoint:

mkdir -p ./data/ckpts

aria2c -x 16 -s 16 -c -k 1M \
  -d ./data/ckpts \
  -o lvp_14B.ckpt \
  https://hf-mirror.com/KempnerInstituteAI/LVP/resolve/main/checkpoints/lvp_14B.ckpt

This produces:

./data/ckpts/lvp_14B.ckpt

4. Start SFT:

accelerate launch main.py \
  +name=final_i2v \
  experiment=exp_video \
  algorithm=wan_i2v \
  dataset=robotwin \
  dataset.data_root=$WORKSPACE/RoboTwin/data \
  dataset.metadata_path=robotwin_videos.csv \
  experiment.num_nodes=1 \
  algorithm.lang_guidance=0 \
  algorithm.hist_guidance=0 \
  experiment.training.batch_size=1 \
  algorithm.gradient_checkpointing_rate=1.0 \
  algorithm.model.tuned_ckpt_path=./data/ckpts/lvp_14B.ckpt

Checkpoints will be saved under:

outputs/<date>/<time>/checkpoints/

Inverse Dynamics Model Training

EVA includes IDM training. The IDM dataset reads raw RoboTwin HDF5 trajectories from the configured RoboTwin task variant:

$WORKSPACE/RoboTwin/data/<task>/<task_config>/data/*.hdf5

IDM training uses the head camera view (observation/head_camera/rgb). The default config is at configurations/dataset/robotwin_idm.yaml.

Example command:

CUDA_VISIBLE_DEVICES=0 accelerate launch main.py \
  +name=idm_train \
  experiment=exp_idm \
  algorithm=idm_resnet_plus \
  dataset=robotwin_idm \
  dataset.data_root=$WORKSPACE/RoboTwin/data

IDM checkpoints are saved to:

outputs/<date>/<time>/checkpoints/

Each checkpoint keeps the legacy-compatible structure:

• model_state_dict
• optimizer_state_dict
• step

GRPO-Based Post-Training

EVA also includes the Flow-GRPO post-training path used for executable video alignment.

The RL experiment is configured by:

• configurations/experiment/exp_flow_grpo.yaml

RL post-training uses the inverse-dynamics smoothness reward and requires an explicit IDM checkpoint:

• experiment.training.reward_model_path=./outputs/<date>/<time>/checkpoints/best.pt

Example command:

accelerate launch main.py \
  +name=rl_debug_test \
  experiment=exp_flow_grpo \
  algorithm=wan_i2v \
  dataset=robotwin \
  dataset.data_root=$WORKSPACE/RoboTwin/data \
  dataset.metadata_path=robotwin_videos.csv \
  experiment.num_nodes=1 \
  experiment.training.batch_size=1 \
  experiment.training.reward_model_path=./outputs/<date>/<time>/checkpoints/best.pt \
  algorithm.model.use_lora=True \
  algorithm.model.lora_rank=32 \
  algorithm.lang_guidance=0 \
  algorithm.hist_guidance=0 \
  algorithm.gradient_checkpointing_rate=1.0

The RL experiment saves:

• Accelerate training state under outputs/<date>/<time>/checkpoints/
• LoRA adapters under outputs/<date>/<time>/checkpoints/<epoch-step>/lora_adapter/
• Reward visualization plots under outputs/<date>/<time>/idm_plots/

---

🧩 Acknowledgments

We thank the authors of the following open-source projects for their valuable contributions:

• large-video-planner
• Wan2.1
• flow-grpo

📚 Citation

If you find our work helpful, please cite:

@misc{wang2026evaaligningvideoworld,
  title={EVA: Aligning Video World Models with Executable Robot Actions via Inverse Dynamics Rewards},
  author={Ruixiang Wang and Qingming Liu and Yueci Deng and Guiliang Liu and Zhen Liu and Kui Jia},
  year={2026},
  eprint={2603.17808},
  archivePrefix={arXiv},
  primaryClass={cs.RO},
  url={https://arxiv.org/abs/2603.17808}
}