Controllability of grasps and manipulations in multi-fingered hands

Manipulation of objects utilizing gravity and using general equilibrium grasps, which are not necessarily force-closure, is discussed. Examining the controllability of the object's dynamics, in the presence of gravity, leads to the conclusion that almost all equilibrium grasps are locally controllable. This fact is used to show that manipulation from any one equilibrium point, to any other, is possible if there is a continuity of equilibrium points between them. In addition, the equilibrium grasps can be used for changing grasps with walking finger manipulation. The system controllability matrix is also used to test grasp quality, depending not only on kinematic values but also on object orientation and dynamic properties.