| --- |
| tags: |
| - mujoco |
| - reinforcement-learning |
| - robotics |
| - humanoid |
| - bipedal-locomotion |
| --- |
| |
| # TwoLeg: a biped learning to walk in MuJoCo |
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| Work in progress. The robot does not walk yet. This repo holds the training code, the eval gate, and the audit trail of every attempt. |
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| ## Latest rollout |
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| <video width="480" height="360" controls> |
| <source src="https://huggingface.co/kenpeter123/twoleg/resolve/main/walk_latest.mp4" type="video/mp4"> |
| Your browser does not support the video tag. |
| </video> |
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| 8 s rollout from run `2026-10-18_21-53-55`, training step 94,208,000 (checkpoint `step_94208000.pt`), held command 0.3 m/s forward. The clip stays upright (torso 0.263-0.286 m) but advances only about 0.03 m, so it still does not walk. |
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|  |
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| Leg assembly this policy drives: hip, knee, and ankle servos per leg, generated from the reference CAD by `training/scripts/generate_twoleg_model.py`. |
|
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| ## What counts as walking |
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| `training/scripts/verify_metrics.py` returns WALKS only when one rollout satisfies all six, per environment: |
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| - torso upright across the final 50-step window |
| - each foot loaded more than half the steps |
| - signed forward speed above 0.05 m/s |
| - stance transfers above 0.4 Hz |
| - knee bends more than 0.35 rad peak-to-peak |
| - hip swings more than 0.20 rad peak-to-peak |
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| Speed is signed travel along each environment's own heading, so walking backwards fails. A missing or stale measurement file fails the loop instead of reading defaults. |
|
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| ## What is here |
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| - `training/src/twoleg_training/` — the mjlab velocity task, rewards, curriculum, and robot constants |
| - `training/scripts/` — `verify_metrics.py` (the gate), `eval_walk.py` (long-horizon signed travel), `walk_loop.py` (train-and-gate loop) |
| - `training/tests/` — gate unit tests, including three failure shapes the old gate accepted |
| - `training/assets/twoleg.xml` — the generated model |
| - `robot_item/`, `twoleg_mjcf/` — reference CAD, renders, and assembly clips |
| - `.audit/` — the decision trail |
|
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| ## Reproduce the gate |
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|
| ```bash |
| uv run python training/scripts/verify_metrics.py \ |
| --checkpoint <path/to/model.pt> --command 0.1 \ |
| --steps 250 --envs 4 --device cuda:0 |
| ``` |
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| Exit 0 is WALKS, 1 is NO-WALK. The sidecar lands next to the checkpoint as `verify_metrics_cmd0.10.json`. |
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| ## Source |
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| Development happens at [kenpeter/twoleg](https://github.com/kenpeter/twoleg) on GitHub. This repo is a snapshot. |
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