Pushing multiple objects using equivalent friction center

Discusses the manipulation of multiple objects by pushing. When manipulating ultiple objects, relative motion between two objects such as sliding and rotation may occur. We propose velocity based pushing where the region of the pusher´s velocity causing the desired relative motion at each contact point is obtained as a common space of regions causing the relative motion at one of the contact points. When obtaining the velocity region, we use the equivalent center of friction (ECOF) which is an extension of the conventional COF and which is same as COF when the object translate. Experimental results are also included to show the effectiveness of our idea