Institute for Physical AI @ BMI · a demonstration
A hand, taken apart three ways: the fingers that hold, the rule that decides if a grip will slip, and the brain that chooses where to grab. This is the body — drag to turn the hand over, then take it apart. You expect a robot to need a crushing grip; the truth is the opposite, and it is set by something other than strength. The source on the right runs the real contact mechanics, so it cannot lie to you.
Provenance. Holding is a contact problem, not a strength problem. For an antipodal pinch, friction supplies at most μ·F of grip per finger, so to carry a weight W the squeeze must only satisfy 2·μ·F ≥ W — that is, F ≥ W/(2μ). With ordinary friction that is about the object's own weight, and squeezing any harder buys nothing. What the grip cannot do without geometry is resist a twist — that is the next lesson. All numbers are computed live by the Institute's open grasp core. The 3D model is illustrative; the numbers are exact.