This paper presents a planner which explores an unknown polyhedral object with a multifingered hand in a systematic way by constructing the manipulation-model of the object. The manipulation-model of an
object we proposed previously is a database which consists of landmark orientations of the object, the applicability of manipulation primitives to them and intertransformations among them. In this paper,
two regrasping primitives, rotation and pivoting, are employed. A multifingered hand probes a given unknown object for pivot/rotation axes. If a new axis is found, the planner recursively
performs pivoting or rotation-test (which is similar to rotation but does not actually rotate the object) about the found axis and searches the object for more axes. The manipulation-model
of the object is constructed based on the found axes. An experiment for constructing a manipulation-model of a non-convex polyhedral object is conducted using a fourfingered hand. Force/torque sensors mounted
on the fingertips collect the data of the object. A geometrical model of the object is also constructed.