# t000__ep003__blocks

- **suite / variant:** `` / ``
- **instruction:** Stack the yellow block on the wooden block
- **success:** False
- **control steps:** 1955  (38.8s at 50 Hz)
- **policy inferences:** 337  (replan_steps=6)
- **video:** `blocks/ep003/rollout.mp4`
- **features:** `337` prefix tensors (`prefix`; model=``)

## Semantic timeline

| seconds | control_step | policy_step | phrase |
|---|---|---|---|
| 0.0–3.0 | 0–150 | 0–25 | reaching toward yellow block |
| 3.0–6.0 | 151–301 | 25–50 | grasping yellow block |
| 6.0–9.0 | 302–452 | 50–75 | lifting yellow block |
| 9.0–12.0 | 453–603 | 75–100 | moving yellow block near target |
| 12.0–15.0 | 604–754 | 100–125 | lowering yellow block onto target |
| 15.0–18.0 | 755–905 | 125–150 | placing yellow block on wooden block |
| 18.0–21.0 | 906–1056 | 151–176 | resting gripper on tilted block |
| 21.0–24.0 | 1057–1207 | 176–201 | remaining stationary on block |
| 24.0–27.0 | 1208–1358 | 201–226 | idle with end-effector over block |
| 27.0–30.0 | 1359–1509 | 226–251 | holding position near block |
| 30.0–33.0 | 1510–1660 | 251–276 | motionless gripper over wooden block |
| 33.0–36.0 | 1661–1811 | 276–301 | remaining stationary near block |
| 36.0–38.8 | 1812–1954 | 302–325 | idle / no progress |

## Failure

- **yes**
- **onset type:** obvious_mistake
- **onset:** 15.0 s (00:15.0)
- **frame / control_step:** 756 (policy_step=126, chunk_index=0)
- **coarse onset:** 18.0 s (refined=True)
- **mode:** placement_or_insertion_failure
- **reason:** The robot brought the yellow block to the wooden block but misaligned it during placement, leaving the yellow block tilted sideways on top of the wooden block with the gripper stuck against it.
  Summary: misaligned block placement; block left tilted on wooden block
- **recovery:** Re-grasp the yellow block, raise it above the wooden block, align its orientation horizontally, and place it squarely on top of the wooden block.
  Summary: re-grasp yellow block; align and stack on wooden block
- **prevention:** Center the yellow block directly over the top face of the wooden block in a level orientation before lowering and releasing the gripper.
  Summary: align yellow block centered over wooden block; release smoothly
- **justification:** Around 18.0 seconds, the robot attempts to place the yellow block on the wooden block, but releases it at a skewed angle, leaving it tilted unsteadily on top of the wooden block while the gripper remains wedged over it.