Institute for Physical AI @ BMI · a demonstration
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.