GhostTrial — Scorpion spear throw into an uppercut, on a Unitree G1
A fine-tune of NVIDIA's SONIC whole-body controller that performs a two-part
combat phrase the stock controller cannot: a spear throw, a pull back, and a
crouch into a rising uppercut, as one continuous motion under full physics.
Entered in
Ghost Trial 03 (Ultimate Bots hackathon, Martial Arts track).
Code, data and the full pipeline:
https://github.com/SpiRaiL/GhostTrial-publicFiles
| file | what it is |
|---|
model_step_003750_g1.onnx | the encoder trained on G1-space motion — the one this pipeline drives |
model_step_003750_encoder.onnx | motion encoder |
model_step_003750_decoder.onnx | policy decoder |
config.yaml | the training run exactly as it ran |
model_config.yaml | model dimensions, written by the exporter |
How it was trained
Fine-tuned from the SONIC release checkpoint — not trained from scratch — on one
motion: our own capture, retargeted to the G1 and rebuilt twelve times.
| |
|---|
| Base | SONIC release checkpoint (GR00T-WholeBodyControl) |
| Environments | 4096 parallel, Isaac Lab 2.3.2, one H100 on Nebius |
| Checkpoint | step 3750 |
| Actor / critic LR | 2e-5 / 1e-3, gamma 0.99, seed 0 |
| Motion | data/motion_lib_capture/robot/t12 in the GitHub repo |
| Export | tools/export_onnx.sh <checkpoint> /gt/data/motion_lib_capture/robot/t12 |
Data
A movement phrase written as a brief and filmed by a commissioned performer,
lifted to 3D pose from monocular video, retargeted to the G1's 29 DoF, then
corrected across eleven revisions for self-collision, foot contact and joint
limits before any GPU time was spent. The motion data is in the GitHub repo; the
performer's video is not published.
The 1992 Mortal Kombat behind-the-scenes footage that inspired the move is style
reference only. It never entered training and is not distributed.
Before and after
Same reference motion, stock SONIC against this fine-tune, both under full
physics in Isaac Lab:
| stock | this model |
|---|
| Pelvis height range over the phrase | 74.3–78.7 cm (4 cm) | 46.3–79.3 cm (33 cm) |
| The crouch the move is built on | never happens | performed |
| Drift from start over 14 s | 0 cm | 4 cm |
The stock controller stays upright and marks time. This one drives into the
stance, drops into the crouch and carries the arm through.
Limitations
- It holds 97% double support where the target asks for 58%: it plants where
the reference leaves the floor, so the airborne part of the uppercut is damped.
- Trained on one phrase with standing, idle and walking control takes alongside
it. Walking and turning were not separately evaluated against this checkpoint.
- Simulation only. It has never run on a physical G1.
Licence
Derived from SONIC model weights, which are under the NVIDIA Open Model
License — that licence governs this derivative too. The pipeline code in the
GitHub repo is ours.
