# t000__ep016__blocks

- **suite / variant:** `` / ``
- **instruction:** Stack the yellow block on the wooden block
- **success:** False
- **control steps:** 932  (18.5s at 50 Hz)
- **policy inferences:** 162  (replan_steps=6)
- **video:** `blocks/ep016/rollout.mp4`
- **features:** `162` prefix tensors (`prefix`; model=``)

## Semantic timeline

| seconds | control_step | policy_step | phrase |
|---|---|---|---|
| 0.0–3.0 | 0–151 | 0–25 | approaching yellow block |
| 3.0–6.0 | 152–303 | 25–50 | closing gripper and missing yellow block |
| 6.0–9.0 | 304–455 | 50–75 | re-descending and attempting grasp |
| 9.0–12.0 | 456–607 | 76–101 | pinching yellow block and slipping |
| 12.0–15.0 | 608–759 | 101–126 | repeated grasp attempts on block |
| 15.0–18.1 | 760–911 | 126–151 | oscillating over yellow block |
| 18.1–18.5 | 912–931 | 152–155 | remaining stationary over yellow block |

## Failure

- **yes**
- **onset type:** obvious_mistake
- **onset:** 3.504950495049505 s (00:03.5)
- **frame / control_step:** 177 (policy_step=29, chunk_index=3)
- **coarse onset:** 3.5 s (refined=False)
- **mode:** grasp_failure
- **reason:** The robot attempted to grasp the yellow block but failed to establish a secure grip, resulting in repeated failed grasp attempts and slipping without picking up the block.
  Summary: failed grasp on yellow block; unable to lift block
- **recovery:** Re-open the gripper, center the end-effector directly over the yellow block, lower to surround the block, and close the gripper securely before lifting.
  Summary: re-open gripper; center over yellow block; grasp securely
- **prevention:** Align the gripper accurately with the center and orientation of the yellow block before closing the fingers to guarantee a firm grasp on the first try.
  Summary: align gripper centered over block; grasp firmly
- **justification:** At approximately 3.5 seconds into the rollout, the robot closes its gripper on the yellow block but fails to secure it. The block slips out, leading to continuous failed grasping attempts throughout the remainder of the video.