Rolling Based Manipulation for Multiple Objects

1 I n t r o d u c t i o n Multifingered robot hands have potential advantages in performing various tasks with the dexterity of human hands. While much research has been done on multifingered robot hands, most of works have implicitly assumed that a multifingered hand manipulates only one object. Under such a condition, severn grasping issues have been studied. Let us now consider the case where a multi-fingered hand approaches and envelopes two cylindrical objects with significant friction[9] as shown in Fig.1. For two objects satisfying the rolling contact each other, we can expect that a multifingered hand can easily achieve an enveloping grasp by simply pushing two links contacting with the objects. During the lifting phase, links and two objects behave as if they were just connected by mechanical gears. Due to this mechanical properties, achieving an enveloping grasp for two objects seems to be even easier than for a single object under significant friction. This is a potential advantage for manipulating two objects, simultaneously. We can find another advantage for manipulating multiple objects. Let us consider the case where a human picks up and transfers small objects such as coins, beans or such like from a table. In such a case, a human often grasps more than one object and manipulate them case by case. Generally, we can expect that treating multiple objects simultaneously makes it possible to achieve a handling task efficiently. These 0 -7803 -5886 -4 /00 /$ 10 .00© 2000 IEEE 3888 z///i/////i//// t/Z/Z/Z/Z//////