Model Description
SOLE-R1 predicts robot task progress from visual observations. Given a video and a task description, the model outputs a reasoning trace and a scalar progress estimate.
Expected output format:
<think>reasoning about task progress</think><answer>progress%</answer>
The progress estimate is intended to serve as a dense reward signal for robotic reinforcement learning, especially when manually engineered rewards are unavailable.
Quick Start
The recommended interface for inference is RewardGen:
# pip install -U rewardgen from rewardgen import generate, video_plot # test_videos provided at the github repo: https://github.com/Philip-MIT/rewardgenvideo_paths = [ "test_videos/robosuite/lift/unsuccessful/robosuite_lift_episode_12_unsuccessful_max_reward_38.mp4"] task_description = "Pick up the cube from the table." rewards, reasoning_traces = generate( model="SOLE-R1", task_description=task_description, video_paths=video_paths, view_type_per_video=["external and wrist"], verbose=False,)print(rewards)print(reasoning_traces) # Plotting with show_reasoning_traces=Trueoutput_sole = {"model": "SOLE-R1", "rewards": rewards[0], "reasoning_traces": reasoning_traces[0]}video_plot( outputs=[output_sole], plot_save_path='model_outputs/sole-r1/robosuite/lift/unsuccessful/robosuite_lift_episode_12_unsuccessful_max_reward_38.mp4', video_path=video_paths[0], show_reasoning_traces=True, task_description=task_description, verbose=False)
Optional pre-download:
from rewardgen.utils.model_utils import get_model_dirget_model_dir("sole-r1")
The model is trained to reason over robot task progress using prompts that include:
- A robot task description
- The first timestep progress, typically
0%
- The previous timestep progress
- Visual observations from the first, previous, and current timesteps
- Multiple camera views when available, such as external and wrist cameras
Example task description:
Pick up the cube from the table.
The expected output format is:
<think>[reasoning about visual task progress]</think><answer>[current task progress]%</answer>
Example:
<think>The gripper has moved closer to the cube but has not yet grasped or lifted it. This indicates incremental progress from the previous timestep.</think><answer>22%</answer>
Downstream systems should parse the numeric value inside <answer>...</answer> as the reward/progress estimate.
Training Data
The model was trained on the SOLE-R1-8B training dataset.
The dataset contains robot task progress examples with images, prompts, reasoning completions, and progress labels.
It also includes a diverse collection of general spatial and multi-frame temporal reasoning data (e.g., from SSR-CoT, SpatialVLM, Spot-the-diff, Embodied CoT, RoboVQA, Robo2VLM-Reasoning) to serve as a foundational layer of our training mixture.
The full dataset is approximately 2TB.
Streaming example:
from datasets import load_dataset ds = load_dataset( "Philip-MIT/sole_training_data", split="train", streaming=True,) for row in ds: print(row) break
Citation
BibTeX:
@misc{schroeder2026soler1, title={SOLE-R1: Video-Language Reasoning as the Sole Reward for On-Robot RL}, author={Philip Schroeder and Thomas Weng and Karl Schmeckpeper and Eric Rosen and Stephen Hart and Ondrej Biza}, year={2026}, eprint={2603.28730}, archivePrefix={arXiv}, primaryClass={cs.RO}}
License
This repository is released under the MIT License.