Study of the friction effect on the stability of a three-rigid link object manipulated by two cooperative robot arms

This work presents a study of the frictional effect on the stability of a three-rigid link object manipulated by two cooperative robot arms in a plane. It is supposed that the three-rigid link object interacts with the two robot arms at multi contact points to perform the nonprehensile manipulation of the object. The object is figured out in a way such that one of the arms is in contact with two links of the object, while the other arm is free to slide along the third link. The effect of changing frictional forces at the contact points as well as their directions on the stability of the manipulated object is to be explored by defining the system constraints. A definition of what is called the “Stability Margin” is obtained. For the same orientation of the object links, the Stability Margin is a region of equilibrium contact points between the sliding arm and the corresponding object link where the robot arm could be placed in without dropping the object. Later, an experimental system consisting of a three-rigid link object and a two planar robot arms manipulation system is equipped to verify the concept.