grasping-concave-contour
From the author
Grasp an awkward rigid part by the waists in its own silhouette — take the alpha shape of its point cloud from above, find where that boundary turns inward, and close the jaws across a pair of those inward runs. Use when a part has no graspable long axis and no pair of parallel walls an OBB would find — pliers and scissors gripped at the joint, a spool at its neck, a gear between two teeth, a bulb socket at its skirt. Use grasping-linear-feature instead for handles, rods and shafts, and grasping-short-axis when an upright box is enough.
Install
npx skills add graph-robots/open-robot-skills --skill grasping-concave-contour -a claude-code
Installs to .claude/skills/grasping-concave-contour/ · Each command fetches the skill straight from GitHub with the open skills CLI.
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Similar skills
Closest to this one by what they do and when they are used.
- grasping-linear-featuregraph-robots/open-robot-skillsFit the full 3D axis of an elongated segmented feature and grasp it with a perpendicular, inclination-aware parallel-jaw pose. Use for handles, rods, shafts, tools, utensils, and other linear parts whose pitch or roll matters; use grasping-short-axis instead when an upright OBB and vertical approach are sufficient.Other★ 58
- grasping-short-axisgraph-robots/open-robot-skillsDeterministic short-axis-aligned grasp with CuRobo. The grasp pose is computed geometrically (NOT sampled/scored) — the gripper approaches straight down with its finger-opening axis locked to the OBB's SHORTER horizontal axis, so the jaws close ACROSS the narrow dimension of an elongated target. Use for pan/pot handles, bottles, tools, utensils — anywhere the OBB centroid is graspable but orientation is the thing that matters. An optional offset_from_base node slides the grasp outward along the handle, clear of the heavier object body, when a second OBB of that body is wired in. A scored/sampled pose often holds at close but shears out under the lift; the short-axis pose grips the bar squarely so it survives lift + transport.Documents★ 58
- proposing-side-graspsgraph-robots/open-robot-skillsPropose horizontal (side-entry) grasps swept around an object's oriented box — twelve azimuths ranked by jaw margin. Use when top-down access is blocked by an overhead shelf, a lid or a bin wall, or when the object's vertical dimension is the only one the hand can span. Declines when the object is wider than the jaws from every azimuth.Other★ 58
- proposing-short-axis-graspsgraph-robots/open-robot-skillsPropose top-down grasps whose jaws close ACROSS an elongated object's short axis, derived from its oriented box. Use when the object is longer than it is wide, as the first grasp-proposal rung — a handle, a spanner, a screwdriver, a bar, a laid-down bottle — where closing along the length would put the fingers down the object and meet them on each other. Declines when the short axis is wider than the hand opens, which is the signal to try `proposing-side-grasps` rather than to re-tune this one.Other★ 58
- tipping-over-a-surface-edgegraph-robots/open-robot-skillsTurn a body over on the surface it rests on instead of carrying it — pinch two opposite walls LOOSELY and off centre so the pads act as a pin joint, lift so the surface and gravity stand the body up on its own edge, then press it onto the surface and pull the pins toward you about whichever edge is grounded until it is just past balance, and let go. Use when a rigid grasp cannot transmit the torque a full roll needs (a parallel jaw rolling about its own closing axis), when the body is too big to turn over in hand, or when the arm's envelope cannot follow a held body through the roll.Other★ 58
- anchoring-a-free-endgraph-robots/open-robot-skillsPins one end of a cable with the support hand before any crossing is attempted — asks the support-hand planner for the anchor grasp as joint-space legs, refuses it when its worst IK error is past the limit, streams the legs, closes the jaws to the plan's own width and dwells for the fingers' travel, and carries the solved chain and grasp orientation out on the exit so later pay-outs seed from them. Use when a deformable linear object must be held at one end so a sideways pull bends it instead of dragging the whole thing.Planning★ 58
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