Progress in spatial robot juggling

We review our progress to date in eliciting dynamically dexterous behaviors from a three degree of freedom direct drive robot manipulator whose real-time stereo cameras provide 60 Hz sampled images of multiple freely falling bodies in highly structured lighting conditions. At present, the robot is capable of forcing a single ping-pong ball into a specified steady state (near) periodic vertical motion by repeated controlled impacts with a rigid paddle. The robot sustains the steady state behavior over long periods (typically thousands and thousands of impacts) and is capable of recovering from significant unexpected adversarial perturbations of the ball's flight phase. Gain tuning experiments corroborate our contention that the stability mechanism underlying the robot's reliability can be attributed to the same nonlinear dynamics responsible for analogous behavior in a one degree of freedom forebear. We are presently extending an algorithm for simultaneously juggling two bodies developed in that earlier work to the three dimensional case.