Entertainment robots in theme park environments typically do not allow
for physical interaction and contact with guests. However, catching and
throwing back objects is one form of physical engagement that still
maintains a safe distance between the robot and participants. Using a
theme park type animatronic humanoid robot, we developed a test bed for a
throwing and catching game scenario. We use an external camera system
(ASUS Xtion PRO LIVE) to locate balls and a Kalman filter to predict ball
destination and timing. The robot's hand and joint-space are
calibrated to the vision coordinate system using a least-squares
technique, such that the hand can be positioned to the predicted
location. Successful catches are thrown back two and a half meters
forward to the participant, and missed catches are detected to trigger
suitable animations that indicate failure. Human to robot partner
juggling (three ball cascade pattern, one hand for each partner) is also
achieved by speeding up the catching/throwing cycle. We tested the
throwing/catching system on six participants (one child and five adults,
including one elderly), and the juggling system on three skilled
jugglers.