Passive Dynamic Object Locomotion by Rocking and Walking Manipulation

This paper presents a novel robotic manipulation technique for transporting objects on the ground in a passive dynamic, nonprehensile manner. The object is manipulated to rock from side to side repeatedly; in the meantime, the force of gravity enables the object to roll along a zigzag path that is eventually heading forward. We call it rock-and-walk object locomotion. First, we examine the kinematics and dynamics of the rocking motion to understand how the states of the object evolve. We then discuss how to control the robot to connect individual rocking motions into a stable gait of the object. Our rock-and-walk object transportation technique is implemented using a conventional manipulator arm and a simple endeffector, interacting with the object in a nonprehensile manner in favor of the passive dynamics of the object. A set of experiments demonstrates successful object locomotion.