Imma Perfetto
Cosmos science journalist
The latest in ping-pong playing robots has outperformed its predecessors and may soon surpass the strike speeds of top human players, according to its creators from the Massachusetts Institute of Technology’s (MIT) Biomimetic Robotics Laboratory.
The team designed the multijointed robotic arm to wield a standard ping-pong paddle and hit an incoming ball towards a precise location on a table. They report that initial tests show the robot has a return hit rate of about 88%, and an average strike speed of 11 metres per second.
The results of the experiments will be presented in a paper at the IEEE International Conference on Robotics and Automation (ICRA) in Atlanta, USA, later this month. The paper has not yet been peer reviewed.
According to the researchers, further tweaks to the system have since resulted in recordings of up to 19m/s, which is faster than existing ping-pong-playing systems and approaches the capabilities of advanced human players, who can return balls at speeds of 21-25m/s.
“The problems that we’re solving, specifically related to intercepting objects really quickly and precisely, could potentially be useful in scenarios where a robot has to carry out dynamic manoeuvres and plan where its end effector will meet an object, in real-time,” says study co-author and MIT graduate student, David Nguyen.
“If you think of the spectrum of control problems in robotics, we have on one end manipulation, which is usually slow and very precise, such as picking up an object and making sure you’re grasping it well.
“On the other end, you have locomotion, which is about being dynamic and adapting to perturbations in your system.
“Ping-pong sits in between those. You’re still doing manipulation, in that you have to be precise in hitting the ball, but you have to hit it within 300 milliseconds.”
The robotic arm is fixed to one end of a standard ping-pong table and surrounded by several high-speed motion capture cameras to track balls bounced towards it. An algorithm uses this to predict what speed and paddle orientation the arm should execute to hit an incoming ball with a particular type of swing: loop (or topspin), drive (straight-on), or chop (backspin).
“A big thing about table tennis is predicting the spin and trajectory of the ball, given how your opponent hit it, which is information that an automatic ball launcher won’t give you,” says study co-author and MIT graduate student, Kendrick Cancio.
“A robot like this could mimic the manoeuvres that an opponent would do in a game environment, in a way that helps humans play and improve.”
In its current form, the robot has limited mobility and reach and can mostly return balls that arrive within a crescent-shaped area around the midline of the table. In the future, the engineers plan to rig the bot on a wheeled platform to enable it to cover more of the table and return a wider variety of shots.
“We are exploring how the techniques used in playing ping-pong could translate to a more generalised system, like a humanoid or anthropomorphic robot that can do many different, useful things,” adds Cancio.
