# t000__ep028__blocks

- **suite / variant:** `` / ``
- **instruction:** Stack the yellow block on the wooden block
- **success:** False
- **control steps:** 934  (18.5s at 50 Hz)
- **policy inferences:** 160  (replan_steps=6)
- **video:** `blocks/ep028/rollout.mp4`
- **features:** `160` prefix tensors (`prefix`; model=``)

## Semantic timeline

| seconds | control_step | policy_step | phrase |
|---|---|---|---|
| 0.0–3.0 | 0–150 | 0–25 | approaching yellow block |
| 3.0–6.0 | 151–301 | 25–50 | grasping yellow block |
| 6.0–9.0 | 302–452 | 50–75 | moving yellow block toward wooden block |
| 9.0–12.0 | 453–603 | 75–100 | lowering yellow block onto wooden block |
| 12.0–15.0 | 604–754 | 100–125 | positioning yellow block on wooden block |
| 15.0–18.0 | 755–905 | 125–150 | releasing yellow block; block slipping off |
| 18.0–18.5 | 906–933 | 151–155 | retreating gripper |

## Failure

- **yes**
- **onset type:** obvious_mistake
- **onset:** 16.567460317460316 s (00:16.6)
- **frame / control_step:** 835 (policy_step=139, chunk_index=1)
- **coarse onset:** 15.5 s (refined=True)
- **mode:** placement_or_insertion_failure
- **reason:** The robot released the yellow block onto the wooden block without proper alignment, causing the yellow block to slide off and fall onto the table as the gripper opened.
  Summary: unstable placement; block sliding off
- **recovery:** Re-grasp the yellow block from the table surface, align it directly over the center of the wooden block, and place it gently.
  Summary: re-grasp yellow block; stack stably on wooden block
- **prevention:** Ensure the yellow block is centered and leveled over the wooden block prior to opening the gripper.
  Summary: center yellow block; release gently on target
- **justification:** The robot successfully picked up the yellow block and brought it to the wooden block, but upon releasing at ~15.5s, the placement was misaligned and unstable, causing the yellow block to fall off onto the table by 17.0s.