Institute for Physical AI @ JBI · a demonstration

Why does a grip slip?

Squeezing is not the whole story, you have fumbled a jar lid with a grip that felt plenty tight. There is one geometric rule that decides whether a grasp holds or spins free, and it has nothing to do with how hard you press. Watch two grips on the board with the same squeeze: one catches, one twists out. The source runs the real force-closure test, so it cannot lie to you.

Provenance. A grasp holds iff its contact forces: each confined to its friction cone, can positively span every wrench the object might feel: force closure. The board computes the Ferrari–Canny quality Q, the radius of the largest wrench the grip can resist; Q > 0 means caught, Q ≤ 0 means it can be twisted out no matter the squeeze. The two grips shown carry the identical squeeze, only the geometry differs. All numbers computed live by the Institute's open grasp core. The 3D model is illustrative; the numbers are exact.