A three-fingered hand grips an object using force closure — each fingertip presses with enough friction that the combined contact forces resist gravity and disturbance from every direction. To rotate the object past the small angle the wrist alone can reach, the hand uses finger gaiting: one finger at a time releases its contact, swings to a new position further around the object, and re-presses. While one finger is mid-transfer, only two contacts hold the object, so the stability metric dips; once the third finger re-lands, force closure is restored and the object has advanced a few degrees.
stability ~ f(activeContacts)
if activeContacts < 3: stability drops sharply
gaitCycle: release(finger_k) -> reposition -> reclose -> verify closure
- Target rotation — total angle the object should be reoriented through; larger targets require more finger-gaiting cycles.
- Gait speed — how fast each finger's release-move-reclose transfer plays out.
- Grasp stability — live estimate of whether current finger contacts can resist the object's weight; it dips whenever a finger is mid-transfer and only two contacts remain.
Real-world relevance: in-hand manipulation via finger gaiting lets dexterous robot hands reorient parts, tools and packages without repeatedly setting them down and re-grasping.