---
license: apache-2.0
library_name: openpi
tags:
- robotics
- tactile
- vla
- pi05
- openpi
- xarm
- ablation
---

# pi05 xArm tube - `binmarker9` (9 arrows/finger, contact bit only)

pi0.5 LoRA fine-tune for the xArm **tube** task (`"pick up the tube and put it in the nearest slot"`), trained on frames
with the **`binmarker9`** tactile overlay burned in.

## What the overlay encodes

**Only the per-finger binary contact bit.** Both force **direction** and force
**magnitude** are omitted:

| Signal | Present? |
|---|---|
| Binary contact bit | YES |
| Force direction | NO - fixed to the sensor-frame pad normal |
| Force magnitude | NO - fixed length (0.12 m) |

9 arrows per finger (one at each of the 9 forward-kinematics-projected sensor pad cells), drawn iff that finger's contact
state is ON (max-cell metric, hysteresis ON >= 0.25 / OFF < 0.18, 2-on/3-off
debounce, state reset per episode).

Verified tactile-independence: **0 max pixel change across 300 randomized force
readings at a fixed pose** - the pixels provably carry no force information.

## Ablation pair

| Task | 1 arrow | 9 arrows |
|---|---|---|
| tube | [`binmarker`](https://huggingface.co/EdwardoSunny/pi05_xarm_tube_binmarker_lora) | [`binmarker9`](https://huggingface.co/EdwardoSunny/pi05_xarm_tube_binmarker9_lora) |

Hyperparameters are identical across both arms (LoRA `gemma_2b_lora` +
`gemma_300m_lora`, batch size 8, cosine schedule warmup 500 / peak 1e-4 /
decay 20k to 1e-5, AdamW grad-clip 1.0, no EMA, 20k max steps with early
stopping), so differences are attributable to the overlay alone.
Trained 5800 steps.

## Contents

Orbax checkpoint (`params/`) plus `assets/` norm stats - inference-ready.
`train_state/` (optimizer state) is intentionally excluded.

## Inference

```bash
python examples/xarm/inference/run_xarm_inference.py \
  --checkpoint <local-path> \
  --overlay binmarker9_tube
```

The overlay **must** be redrawn at deployment exactly as in training, or the
policy is out of distribution. The inference renderer (`FixedMarkerOverlay`,
variant `binmarker9`) is verified **byte-exact** against the training renderer:
0 max pixel error over 3,566 camera images across all 4 tasks (cube 450,
tube 760, charger 1,122, dishwasher 1,234), 0 contact-state mismatches. The `--overlay` flag requires the per-task suffix
because the per-finger p99 scales differ up to ~6x across tasks.

Observation/action convention: state 8-dim
`[ee_pos_m(3), ee_axis_angle_rad(3), grasp, grasp]`, action 7-dim
`[dxyz_m, d_axis_angle_rad, grasp_pm1]`, 224x224 RGB uint8, 10 Hz, action
chunk 10 (consume 5).

## Paired dataset

[EdwardoSunny/xarm_tube_binmarker9](https://huggingface.co/datasets/EdwardoSunny/xarm_tube_binmarker9)