# t000__ep024__blocks

- **suite / variant:** `` / ``
- **instruction:** Stack the yellow block on the wooden block
- **success:** False
- **control steps:** 481  (9.5s at 50 Hz)
- **policy inferences:** 82  (replan_steps=6)
- **video:** `blocks/ep024/rollout.mp4`
- **features:** `82` prefix tensors (`prefix`; model=``)

## Semantic timeline

| seconds | control_step | policy_step | phrase |
|---|---|---|---|
| 0.0–3.0 | 0–151 | 0–25 | lowering arm toward yellow block |
| 3.0–6.0 | 152–303 | 25–50 | attempting grasp on yellow block |
| 6.0–9.0 | 304–455 | 50–75 | lifting empty gripper |
| 9.0–9.5 | 456–480 | 76–80 | hovering above table |

## Failure

- **yes**
- **onset type:** obvious_mistake
- **onset:** 6.2772277227722775 s (00:06.3)
- **frame / control_step:** 317 (policy_step=52, chunk_index=5)
- **coarse onset:** 5.0 s (refined=True)
- **mode:** grasp_failure
- **reason:** The robot attempted to grasp the yellow block, but failed to secure a firm hold, causing the block to slip out of the gripper as it closed.
  Summary: failed grasp on yellow block; object slipped from gripper
- **recovery:** Re-align the end-effector over the yellow block, close the gripper to grasp it securely, and then place it onto the wooden block.
  Summary: re-align gripper; regrasp yellow block; stack on wooden block
- **prevention:** Position the gripper directly over the center of the yellow block before closing it to ensure a stable grasp prior to lifting.
  Summary: align gripper centered on yellow block; secure grasp before lifting
- **justification:** At 5.0 seconds, the robot closes its gripper on the yellow block, but fails to pinch it securely. By 6.0 seconds, the block slips out and remains on the table while the empty gripper lifts away, rendering the task uncompleted.