Throwing, Catching, and Balancing of a Disk With a Disk-Shaped End Effector on a Two-Link Manipulator

In this paper, nonprehensile throwing, catching, and balancing of a disk-shaped object by a two-link planar manipulator mounted with a disk-shaped end effector are presented. Given a goal position, which is out of the robot's reachable space, the required release position and velocity for throwing are first determined. The throwing manipulation is proposed in a way that the arm follows a planned trajectory between the ready and the release position to achieve the required velocity at the release position. Catching is performed in a way that it reduces impact when making contact. Balancing control is then applied to the disk-shaped end effector to prevent the object from falling after catching. The proposed approach was implemented on an experimental setup built for verification and the results are provided.