Reading Bingo Balls with Microcontrollers

Every once in a while a project comes along with that magical power to consume your time and attention for many months. When you finally complete it, you feel sorry that you don’t have to do anything more.

What is so special about this Bingo ball reader? It may seem like an ordinary OCR project at first glance; a camera captures the image and OCR software recognizes the number. Simple as that. And it works without problems, like every simple gadget should.

But then again, maybe it’s not that simple. Numbers are scattered all over the ball, so they have to be located first, and the best candidate for reading must be selected. Then, numbers are painted onto a sphere rather than a flat surface, sometimes making them deformed to the point where their shape has to be recovered first. Also, the angle of reading is not fixed but somewhere on a 360° scale. And then we have the glare problem to boot, as Bingo balls are so shiny that every light source reflects as a saturated bright spot.

So, is that all of it? Well, almost. The task is supposed to be performed by an embedded microcontroller, with limited speed and memory, yet the recognition process for one ball has to be fast — 500 ms at worst. But that’s just one part of the process. The project includes the pipelined mechanism which accepts the ball, transports it to be scanned by the OCR and then shot by the public broadcast camera before it gets dumped. And finally, if the reading was not reliable enough, the ball has to be subtly rotated so that the numbers would be repositioned for another reading attempt.

Despite these challenges I did manage to build this system. It’s fast and reliable, and I discovered some very interesting tricks along the way. Take a look at the quick demo video below to get a feel for the speed, and what the system “sees”. Then join me after the break to dive into the details of this interesting embedded build.

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Circular Saw Cuts Balls… Wooden Balls, Don’t Worry

Ever wonder how wood spheres are made? Normally they are made on a wood lathe with some fancy jigs and fixtures. [Izzy Swan] set out to bring wood sphere manufacturing to the masses by designing an inexpensive machine that uses a standard circular saw to carve a block of wood into a sphere.

Here’s how it works: a piece of wood is held in a wood fixture and spun using a hand drill. The fixture and drill are mounted to a wooden ring that rotates about a perpendicular axis. The user manually moves the entire assembly back and forth about that second axis while spinning the drill. Meanwhile, a circular saw is moved closer and closer to the soon-to-be-sphere, nibbling away little by little. After most of the material has been cut from the block of wood, it is removed from the fixture and spun 90 degrees to cut the two remaining nubs. The end result is a pretty nice looking sphere.

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CNC ping pong printer uses simple construction

spherebot

This is one of the simplest CNC builds we’ve seen but it still functions quite well. It’s a clone of the EggBot, but is aimed at printing on spherical Ping Pong balls rather than oblong eggs. [Chad] calls it the Spherebot, but you should be careful not to confuse it with the morphing sphere robot which can walk around like a hexapod.

The project is both mechanically and electronically simple. The body of the printer is made up of three acrylic plates, which we’re sure were clamped together when drilling holes to guarantee proper alignment. Threaded rod and nuts are used to mount the plates to one another, as well as to hold the sphere in place while printing. One stepper motor turns the ball while the other pivots the pen mount. A servo motor is responsible for lifting the pen. The entire thing is driven by an Arduino along with two stepper motor driver boards. Don’t miss [Chad’s] presentation embedded after the break.

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Dyson engineers’ hacks traverse robot obstacle course

2012-dyson-challenge

These guys are all engineers who are employed by Dyson. They’re holding remote control creations made from Dyson parts. This time around the object of the challenge was to build a bot based on a the Dyson ball and race it through an obstacle course.

This sort of thing is right up our alley, but unlike the last time Dyson engineers shrugged off the daily grind to hack their own hardware, this doesn’t show off nearly enough of the festivities. Sure the pair of videos embedded after the break make a great trailer for the event, but we would love to have seen 90 seconds devoted to each of the entries. Alas, you do get to see most of the winning unit’s obstacle course run which includes a distance route, navigating through rough terrain, and negotiating a high path where falling off the edge is a real threat.

Maybe the engineers themselves will post details about their own builds like the contestants in Sparkfun’s autonomous vehicle contest do.

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360 degree photography uses very easy post-processing

[Pixel_Outlaw] has been working on a method to capture 360 images with his camera. He’s using a shiny Christmas ball ornament to reflect the entire room into the lens of the camera. In the unwrapped image you can make out the three legs of his tripod. In that snapshot he laid the ornament on the floor and pointed the camera straight down from above.

What catches our attention is the post processing he used to unwrap the image. He loaded up The Gimp, an open source image manipulation program, and used just three steps to unwrap the image. First he cropped the picture so that it was square and the spherical ornament was perfectly centered. Then he ran the polar coordinates filter. Finally he scaled the image, setting the width to be Pi times the height. Works pretty darned well for something that doesn’t take much fiddling.

The ornament wasn’t perfectly smooth (or maybe it was a bit dirty) but you can get a much better starting image if you use a bulb with a silver reflector like we saw in this older hack.

Spherical multitouch rig

We all love a little bit of multitouch, but we’ve seen so many setups that it is getting a bit less exciting. This one will get your attention with its unique shape. It is a spherical multitouch using all open source software. Well, since the poles are unusable, it might just be toroidal, or cylindrical, but it is still impressive. They are using a convex mirror mounted to the upper most point of the frosted sphere to reflect a projector mounted at the bottom of the base. A web cam pointed at that same mirror picks up reflected IR light from a few emitters. You can catch a video of it after the break.

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Robots in space

SPHERES (Synchronized Position Hold, Engage, Reorient Experimental Satellites) are experimental robots made at MIT for the purpose of testing robot locomotion in space. As you can see in the video above, they are capable of maneuvering pretty well. They seem to hold formation fairly tightly. They are using compressed CO2, through 12 different thrusters for positioning. They should be capable of autonomously navigating around each other as well as docking to one another.