Progress in spatial robot juggling

Abstract

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.