by Matt MasonThis is a somewhat cursory survey of work in robotic juggling. I interpret juggling broadly, to include pretty much any machine that controls the motions of flying objects by catching, throwing, or hitting. Thus running is a kind of self-juggling, and ping-pong is adversarial juggling.
The robot's planner incorporated a model of ball flight and impact, and used these models to plan a nominal trajectory for the paddle. This nominal trajectory was then refined by iterated simulations, with concurrent adjustment of goals as better estimates of the ball's motion became available.
Schaal, Atkeson, and Botros  built a special devil sticking robot. The problem is simplified by mounting the devil stick so that it has only three degrees of freedom, rather than the usual six. A long rod is attached perpendicular to the center of the devil stick. The other end of the long rod is attached to ground by a ball and socket joint. In effect the devil stick is confined to the surface of a sphere.
The machine has two `effector sticks' mounted by springy joints to a `torso'. The effector stick contacts the devil stick at its center of percussion, halting the effector stick and storing its energy momentarily at a springy joint. The collision is effectively inelastic, resulting in a catch. The energy is then transferred back to the devil stick, throwing it to the other effector stick.
The same paper describes other juggling machines, including a machine similar to the Shannon juggler, that bounce-juggles five balls.
Tad McGeer  built a walking machine with a gait resembling a human's, including the knees. The machines does not have motors, sensors, or computers. It was designed so that the intrinsic dynamic behavior produces stable walking patterns. Note the similarity to Shannon's juggler.
Sakaguchi, Masutani, and Miyazaki [10, 7] obtain robot juggling of one or two balls with a single robot hand. The hand makes an elliptical motion, modified by the perceived path of a ball. The hand is a simple funnel, and the balls appear to be very soft. They also describe a robot to play the ball-in-cup game.
Slotine  has programmed a robot to throw and catch balls. Using stereo vision to predict the ball's path, the arm very quickly matches velocities while the fingers close on the ball.
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