# t000__ep044__blocks

- **suite / variant:** `` / ``
- **instruction:** Stack the yellow block on the wooden block
- **success:** False
- **control steps:** 439  (8.6s at 51 Hz)
- **policy inferences:** 76  (replan_steps=6)
- **video:** `blocks/ep044/rollout.mp4`
- **features:** `76` prefix tensors (`prefix`; model=``)

## Semantic timeline

| seconds | control_step | policy_step | phrase |
|---|---|---|---|
| 0.0–3.0 | 0–151 | 0–25 | approaching and aligning with yellow block |
| 3.0–6.0 | 152–303 | 25–50 | grasping yellow block; block drops |
| 6.0–8.6 | 304–438 | 50–73 | moving empty gripper over wooden block |

## Failure

- **yes**
- **onset type:** obvious_mistake
- **onset:** 4.921259842519685 s (00:04.9)
- **frame / control_step:** 250 (policy_step=41, chunk_index=4)
- **coarse onset:** 4.8 s (refined=True)
- **mode:** object_displacement
- **reason:** The robot successfully grasps the yellow block but loses its grip and drops the block while moving toward the target location.
  Summary: dropping grasped object; losing grip during transfer
- **recovery:** Lower the gripper back over the dropped yellow block, establish a secure grasp, lift it, and place it on top of the wooden block.
  Summary: re-grasp yellow block; stack on wooden block
- **prevention:** Maintain a firm and centered grip on the yellow block while lifting and transporting it to prevent it from slipping out.
  Summary: maintain secure grip; transfer block smoothly
- **justification:** At around 4.8 seconds, the yellow block slips out of the robot's gripper and drops back onto the table. The robot then continues moving its empty gripper toward the wooden block, failing the stacking task.