Object pose rotation by pulling up the edge of object under a constraint of ground contact

An object pose manipulation method is proposed to change the posture in a cluttered space. In this paper, graspless manipulation is focused to rotate the object without hard grasping. In the proposed method, the object is pinched with fingers at the parallel surfaces whose contact points make rotation axis since it is assumed the point contact, and the object posture is controlled by only pulling up the pinching points. The object pose is defined by the height of the pinching position and the contact point of the object with the ground. To make smooth rotation by the gravity force, the pinching position is defined to the point away from the center of gravity of the object. First, the proposed method is simulated in the dynamic simulator GAZEBO, and the relationship between the point of pinching height and the force for pulling up is revealed. From the simulation result, in the case of an artificially shaped object such as a triangle or a rectangle, the height at which the direction of the lifting force is reversed can be found. When the direction of the force is reversed, by releaseing the object from the finger, the object rotates by the gravity force and the grounding surface can be changed to another desired surface. Thus, rotation to adjacent surfaces can be easily achieved simply by observing the pulling force. Finally, experimental result using a hand with force sensor show the feasibly of the proposed object pose manipulation.