Ping Pong Ball-Juggling Robot

There aren’t too many sports named for the sound that is produced during the game. Even though it’s properly referred to as “table tennis” by serious practitioners, ping pong is probably the most obvious. To that end, [Nekojiru] built a ping pong ball juggling robot that used those very acoustics to pinpoint the location of the ball in relation to the robot. Not satisfied with his efforts there, he moved onto a visual solution and built a new juggling rig that uses computer vision instead of sound to keep a ping pong ball aloft.

The main controller is a Raspberry Pi 2 with a Pi camera module attached. After some mishaps with the planned IR vision system, [Nekojiru] decided to use green light to illuminate the ball. He notes that OpenCV probably wouldn’t have worked for him because it’s not fast enough for the 90 fps that’s required to bounce the ping pong ball. After looking at the incoming data from this system, an algorithm extracts 3D information about the ball and directs the paddle to strike the ball in a particular way.

If you’ve ever wanted to get into real-time object tracking, this is a great project to look over. The control system is well polished and the robot itself looks almost professionally made. Maybe it’s possible to build something similar to test [Nekojiru]’s hypothesis that OpenCV isn’t fast enough for this. If you want to get started in that realm of object tracking, there are some great projects that make use of that piece of software as well.

Ping Pong Spectrum Analyzer

A spectrum analyzer is a pretty useful tool for working with signals where the size of the frequency components matter. Usually, the display is a screen. Sometimes, you see it done with LEDs. [Mag Laboratories] did it with ping pong balls.

The device uses a processor to calculate a Fourier transform, cutting an audio signal into 16 frequency bands. The processor converts each of these values to a PWM output that drives small fans. The fans blow the ping pong ball up the tube proportional to the fan speed. You can see the result in the video below.

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FPGAs Keep Track of your Ping Pong Game

It’s graduation time, and you know what that means! Another great round of senior design projects doing things that are usually pretty unique. [Bruce Land] sent in a great one from Cornell where the students have been working on a project that uses FPGAs and a few video cameras to keep score of a ping-pong game.

The system works by processing a live NTSC feed of a ping pong game. The ball is painted a particular color to aid in detection, and the FPGAs that process the video can keep track of where the net is, how many times the ball bounces, and if the ball has been hit by a player. With all of this information, the system can keep track of the score of the game, which is displayed on a monitor near the table. Now, the players are free to concentrate on their game and don’t have to worry about keeping score!

This is a pretty impressive demonstration of FPGAs and video processing that has applications beyond just ping pong. What would you use it for? It’s always interesting to see what students are working on; core concepts from these experiments tend to make their way into their professional lives later on. Maybe they’ll even take this project to the next level and build an actual real, working ping pong robot to work with their scoring system!

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Cannon Sucks Balls at 600 mph

Every day we humans hang out and think nothing of the air that is all around us. It is easy to forget that the air has mass and is pulled down to the earth by gravity creating an ambient pressure of about 14.7 psi. This ambient pressure is the force that crushes a plastic bottle when you lower the internal pressure by sucking out the air. [Prof Stokes] from Brigham Young University has used this powerful ambient air pressure as the power source of his ping pong ball cannon.

Instead of filling a reservoir tank with compressed air and using that to fire a projectile, this canon has the air removed from the barrel to create the pressure differential that propels the ping pong ball. The ball is put in one end of a 10 ft long tube. That end of the tube is then covered by a sheet of Mylar. The other end is covered with the bottom of a disposable plastic cup. A vacuum pump is then used to remove the air inside the tube and it is this pressure differential that keeps the plastic cup secured to the end of the tube. When it’s firing time, a knife is used to cut the Mylar at the ping-pong-ball-end of the tube. Air rushes in to fill the vacuum and in doing so accelerates the ping pong ball towards the other end. There is a large jar at the business-end of the cannon that catches the ping pong ball and contains the shrapnel created during the ball’s rapid deceleration!

Since this was a science experiment at a university, some math was in order. Based on the atmospheric pressure and ball cross sectional area, the calculated speed was 570 meters/second or about 1300 mph. The calculations didn’t take into account leakage between the ball and the tube or viscosity of the air so a couple of lasers were set up at the end of the cannon to measure the actual speed – 600 mph. Not too bad for just sucking the air out of a tube!

Ping Pong For The IT Office

The office environment over at [Adam]’s place of employment has recently become one of the many IT-related offices with a ping pong table, a cliché that he readily points out. However, [Adam] and the other folks at the office decided to step up their game a little bit by making this automated ping pong table.

The table first keeps track of the players with specialized RFID tags that are placed in the handle of the paddles. The paddles are unique to each player, and when they are swiped past a reader on the table the scoring system registers the players at the table.

Small capacitive touch sensors on the underside of the table allow the players to increment their score when a point is made. The scoreboard is a simple but a very well-polished interface that has audio cues for each point. The system is also able to keep track of the winners and the overall records are tracked, allowing for office-wide rankings.

This is the best table-related game hack since the internet-connected foosball table, and should be welcome in any office for some extra break room fun at work! All of the code is available on the project site.

The Amazing Ping-Pong Robot was Fake

Well — you guys were right. As it turns out, it was actually a pair of animators who fooled the internet.

Not sure what we’re talking about? Last month, the [Kuka Robot Group] put out a highly polished video showing an industrial robot playing table tennis against the apparent world champion of the sport — it was extremely well done and entertaining to watch, but unfortunately… also fake. Weeks after the first [Kuka] video came out, someone named [Ulf Hoffmann] released another video, a small table tennis playing robot that looked almost feasible.

As some of our readers pointed out:

The movements seemed unnatural for the size of the servos and arm structure. ~ James

CGI. As others have pointed out, the shadow of the arm disappears when the robot is show from the side, even though they were added in the other shots. ~ Brandon

My cgi tip off was the cable under the table. It stretches instead of sliding around. ~ Aj

Notice it’s running Outlook Express and Internet Explorer – no self respecting hacker/maker would run those apps – lol. ~ vonskippy

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Real or Fake? The Amazing Ping-Pong Robot

Would you like to play a robot in ping pong (translated)? We sure would. Inspired by an upcoming face-off between man and machine, [Jakob] wrote in to tell us about [Ulf Hoffmann’s] ping-pong playing robot. If you ever wanted to play ping-pong when no one else was around or are just sick and tired of playing against the same opponents this project is for you. Boy is this thing amazing; you simply must see the robot in action in the video after the break.

While the robot’s build is not documented all in one post, [Ulf Hoffmann’s] blog has many videos and mini posts about how he went about building the paddle wielding wonder. The build runs the range from first ideas, to hand-drawn sketches, to the technical drawings seen above. From these the parts of the arm were built, but the mechanical assembly is only one portion of the project. It also required software to track the ball and calculate how to properly return it. Be sure to browse through his past posts, there is a wealth of information there.

Also be sure to check in on March 11th to see who wins the epic face-off between man and machine. See the trailer (the second embedded video) after the break.

UPDATE: Many commentators are calling this one a fake. It’s so sad to think that, because this is a really cool project. But we’ve changed the title and are asking you to weigh in on whether you think it is real or fake. We’ve also contacted [Ulf] and asked if it is real hardware, or a CGI enhanced video. We’ll let you know if/when we hear back from him.

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