Proposing Side Grasps

proposing-side-grasps

One strategy for the propose stage: horizontal entry, swept around the object.

Why this is its own skill

It is the alternative that exists so a top-down refusal has somewhere to go. proposing-short-axis-grasps declines by measuring a width; it cannot offer a side entry, because approaching horizontally is a different strategy, not a different number. A policy with only one propose rung answers a structural refusal by re-tuning parameters that cannot help.

When to use

• Overhead access is blocked — a shelf plate, a lid, a bin rim above the target.
• The object is flat and wide on top but narrow in profile.
• The top-down rung declined.

When NOT to use

• The object stands against a wall or in a corner and only one azimuth is open. This skill will happily rank a blocked side first; the clearance gate in selecting-reachable-grasp is what makes that safe, so do not use this rung without a selector.
• The graspable feature is a concave interior — a box's silhouette says nothing about concavity.

Recommended subgraph state flow

describe → get_obb → propose → select → END

1. describe — tool: robot.describe_gripper.
2. get_obb — tool: sim.get_object_obb (or geometry.filter_and_compute_obb on the vision body).
3. propose — script: scripts/<sg>/propose_side_grasps.py, inputs target_obb, gripper. Router on route.
4. select — build a pose per candidate with robot.grasp_frame(approach=…, close_heading_deg=…) and walk them with selecting-reachable-grasp. Its clearance gate is what turns "ranked by margin" into "reachable in this scene".

Required end states