Researchers at Zhejiang University in Eastern China have unveiled a pair of table-tennis-playing humanoid robots that have been in development for 4 years. The bipedal twins stand 160cm (5’3″) tall, weigh 55kg (121 lbs) and possess approximately 30 degrees of freedom (7 in each arm). The right hand holds the tennis racket, while the left hands are equipped with three fingers that can grasp and serve the ball. They are able to automatically track the speed, direction, and position of the ping-pong ball using an overhead camera that captures the action at 120 frames per second. With a reaction time between 0.05 and 0.1 seconds and an accuracy to within 2.5cm, the robots were able to successfully rally against each other as well as human opponents.