Ultra-fast robotic arm can play catch

Swiss scientists have developed a robotic arm that can play sports -- or at least can field objects thrown its way. The arm measures a little more than three feet long and features three joints, as well as a highly flexible hand with four fingers. Motionless and open-palmed, the robotic arm looks rather underwhelming at first glance. But toss a ball, racket or a bottle its way and it springs to action, able to react and retrieve the flying object. Designed and built by scientists at Swiss Federal Institute of Technology in Lausanne, Switzerland (EPFL), the robotic arm features a reaction time of less than five hundredths of a second. The mechanized arm isn't so much trained to perform or execute a series of predetermined movements as it is trained to learn and react on the fly. "Today's machines are often pre-programmed and cannot quickly assimilate data changes," explained Aude Billard, head researcher at EPFL's Learning Algorithms and Systems Laboratory. "Consequently, their only choice is to recalculate the trajectories, which requires too much time from them in situations in which every fraction of a second can be decisive." Instead, the new robotic arm is programmed to learn via trial and error; it doesn't get specific directions but examples of possible object trajectories. It's trained to predict through repetition to properly predict where the target object will end up. The robot is fed trajectory information through several cameras set up in the lab. As it practices catching, the robot continues to build a more and more accurate model for the objects' path based on their measured trajectories, speeds and rotational movement. Billard predicts that this new technology will continue to improve. "Increasingly present in our daily lives and used to perform various tasks," she said, "robots will be able to either catch or dodge complex objects in full-motion." The work of Billard and her colleagues at EPFL was detailed this week in the journal IEEE Transactions on Robotics.