Velociraptor Model
A bipedal predator with distinctive sickle claws, trained for locomotion and predatory strike behavior.
Specifications
| Property | Value |
|---|---|
| Hip height | ~0.5m (simulated) |
| Total mass | ~15 kg (simulated, scaled) |
| Hinge joints | 24 |
| Actuators | 22 |
| Observation dim | 67 |
| Action dim | 22 |
Anatomy
- Torso - Elongated body with simplified head/neck
- Legs - Digitigrade hind limbs (hip pitch/roll, knee, ankle, 2 toe digits per leg)
- Sickle claws - Retractable claw on digit 2 of each foot (the weapon)
- Arms - Stub forelimbs with shoulder pitch/roll actuators
- Tail - 5-segment counterbalance (4 actuated segments)
Action Space (22 dims)
| Index | Actuator | Type |
|---|---|---|
| 0-5 | Right leg (hip pitch/roll, knee, ankle, toe d3/d4) | Position |
| 6 | Right sickle claw | Motor |
| 7-12 | Left leg (hip pitch/roll, knee, ankle, toe d3/d4) | Position |
| 13 | Left sickle claw | Motor |
| 14-17 | Tail (pitch 1, yaw 1, pitch 2, pitch 3) | Position |
| 18-19 | Right arm (shoulder pitch/roll) | Position |
| 20-21 | Left arm (shoulder pitch/roll) | Position |
Training Stages
- Balance - Learn to stand without falling
- Locomotion - Walk and run forward
- Strike - Sprint and attack prey with sickle claws
Diagnostic Metrics (Stage 3)
After each training stage the eval command reports:
| Metric | Description |
|---|---|
mean_forward_velocity | Average forward speed (m/s) |
gait_symmetry | Left/right stride symmetry ∈ [0, 1] |
stride_frequency | Step frequency (Hz) |
cost_of_transport | Energy efficiency (lower is better) |
mean_pelvis_height | Upright stability (m) |
mean_heading_alignment | cos θ toward prey ∈ [-1, 1] |
success_rate | Fraction of steps with sickle-claw strike |
min_prey_distance | Closest approach to prey (m) |
Training Results (PPO, 2026-03-15)
Full 3-stage curriculum training with seed 42, 4 parallel environments. Total training time: 11h 25m 15s.
| Stage | Description | Timesteps | Best Eval Reward | Final Eval Reward | Avg Fwd Vel | Avg Ep Length | Duration |
|---|---|---|---|---|---|---|---|
| 1 — Balance | Stand and balance without falling | 6,000,000 | 1964.43 +/- 27.39 | 1839.99 +/- 252.17 | 0.11 +/- 0.07 m/s | 969.5 steps (9.70s) | 2h 57m |
| 2 — Locomotion | Forward walking/running | 8,000,000 | 2678.68 +/- 4.07 | 2677.51 +/- 5.86 | 3.47 +/- 0.02 m/s | 1000.0 steps (10.00s) | 4h 36m |
| 3 — Strike | Sprint and strike prey with sickle claw | 8,000,000 | 1366.19 +/- 76.29 | 1258.93 +/- 305.56 | 2.02 +/- 0.30 m/s | 191.2 steps (1.91s) | 3h 52m |
Key observations:
- Stage 2 achieves perfect episode length (1000/1000 steps) with very low velocity variance (3.47 +/- 0.02 m/s), indicating extremely stable locomotion
- Stage 2 final and best rewards are nearly identical (2677.51 vs 2678.68), showing no overfitting or collapse
- Stage 3 achieves 93.3% strike success rate with short episodes (191.2 steps), demonstrating efficient prey pursuit
Training Videos
Velociraptor PPO training progression across each curriculum stage.
STAGE 1
Balance
Standing without falling
STAGE 2
Locomotion
Walking and running forward
STAGE 3
Strike
Sprinting and attacking with sickle claws
Usage
cd environments/velociraptor
# View the model
python scripts/view_model.py
# Train stage 1
python scripts/train_sb3.py train --stage 1 --timesteps 1000000