Progress in spatial robot juggling

The authors review their progress to date in eliciting dynamically dexterous behaviors from a 3-d.o.f. 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 many thousands of impacts) and is capable of recovering from significant unexpected adversarial perturbations of the ball´s flight phase. Gain tuning experiments corroborate the authors´ contention that the stability mechanism underlying the robot´s reliability can be attributed to the same nonlinear dynamics responsible for analogous behavior in a previous 1-d.o.f. robot