Obstacle avoiding LEGO rover uses CDs for wheels


This rover built by [Sath02] is a great example that you don’t have to be a mechanical engineering wizard to get into robotics. He used LEGO pieces to help ease the difficulty of getting a rover up and running.

In this case the use of LEGO is strictly structural. The electronics are not the NXT parts you would expect to see when working with these popular toy blocks. Instead he’s put the Arduino Palm Plus into service. It’s an Arduino board that has rows of holes at either end to make it LEGO compatible. It also carries an LM293D motor controller and [Sath02] added an XBee module for wireless control.

At the top of the assembly is an IR distance sensor which is used for obstacle avoidance. You may not be interested in building and exact replica, but the techniques he uses for attaching the distance sensor, CD wheels,  and fabricating the rest of the rover are good examples if you take on a LEGO build in the future.

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Is a LEGO 3D printer by definition self-replicating?


LEGO parts are plastic. 3D printers make parts out of plastic. So the transitive property tells us that a LEGO 3D printer should be able to recreate itself. This one’s not quite there yet, mostly because it doesn’t use plastic filament as a printing medium. Look close and you’ll probably recognize that extruder as the tip of a hot glue gun. If all else fails you can use the machine as a precision hot glue applicator.

The instructions to make your own version include the design reference and a few ideas for getting the most out of the glue dispenser. For the design phase [Matstermind] used LEGO Digital Designer. It’s basically CAD with the entire library of LEGO parts available as building blocks. from there he assembled the machine which is controlled by an NXT brick. He goes on to link to a few different printing mediums. There’s instructions for using crayons to make colored glue sticks, as well as a method of printing in sugar using the hot glue extruder.

We remember seeing one other LEGO 3D printer. That one didn’t use an extruder either. It placed blocks based on the design to be printed.

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LegoDuino for kid-friendly microcontrollers


[J. Benschop] is teaching his nine-year-old son electronics by giving him a few wires, LEDs, and batteries. Eventually, the son looked over at his dad’s workbench and wondered what the little bug-shaped rectangles did. Microcontrollers and embedded programming are just a bit too advanced for someone who hasn’t hit a double-digit age, but [J] figured he could still have his son experience the awesomeness of programming electronics by building a custom electronic Lego microcontroller system.

This isn’t as complex as a Lego Mindstorms system. Really, it’s only an ATMega and a 2.4 GHz wireless transceiver. Still, that’s more than enough to add a few sensors and motor drivers, and an awesome introduction to electronics development. The enclosure for the LegoDuino is, of course, compatible with every Lego brick on the planet. It’s made from a 6×16 plate, three blocks high, with enough room for the electronics, three AA batteries, and the IO headers.

Programming an ATMega, even with the Arduino IDE, is a little beyond the capacity of [J. Benschop]’s nine-year-old son, so he made a few changes to the Minibloq programming environment to support the newly created LegoDuino. It’s a graphical programming language that kids of just about any age can pick up quickly, and with the included RF transceiver inside the ‘Duino, it can even be programmed wirelessly.

It’s an amazing piece of work, and much, much simpler than even the noob-friendly Lego Mindstorms. Not as powerful, though, but when you’re just teaching programming and electronics, you really don’t need much.


Prototyping a Maglev train using LEGO


Serious research using not-so-serious equipment? We don’t know about that. What’s wrong with using LEGO as a research platform for a Maglev? This team has been doing so for quite some time and with great results.

A Maglev is a vehicle based on the principles of magnetic levitation. Similar poles of magnets repel each other and this concept can be used to create a friction-less track system. But this raises the problems of braking and locomotion. The build log linked above covers the conception in what is the eighth iteration of the research project. But the video below offers the most concise explanation of their approach to these issues.

The researchers are using magnets positioned in trench of the track as a kind of magnetic gear to push against. A series of electromagnets on the Lego vehicle ride in that track. The can be energized, working as a linear motor to push against those permanent magnets. But how do you know which direction of travel this will cause? That problem was solved by adding a hall effect sensor between each electromagnet. Before switching on the coil the hall effect sensors are polled and a timing scheme is selected based on their value. This is used to push the train up to speed, as well as slow it down for braking.

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LEGO jukebox choses from different CDs


Music used to be delivered on round plastic sheets called Compact Discs. [Ralph] still has some of them lying around which he used in his latest project. It’s a CD changer built out of LEGO pieces. It reminds us of the mid-century jukeboxes that changed out 45s on a record player.

You can’t tell from this image, but the entire disc changer build is shaped to sit atop a computer case. The system is built in two parts. There is a transport arm which moves left and right along the rack of CDs. It uses that black and white strip as an encoder to track its movement. It can reach in, grab a disc, and take it all the way down to the right where it drops it off in a staging area. The second part of the build now takes over, grabbing the disc from the staging holder and rotating it down into the CD tray of the PC. All of this is demonstrated after the jump.

If you’re like us you prefer digital delivery for your music. We haven’t crossed that watershed with video games yet and that’s why we still love this Xbox 360 disc changer hack.

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Hackaday Links: Sunday, April 21st, 2013


Regular reader and master hacker [Bill Porter] got married. Congratulations [Bill] and [Mara]! The two of them just couldn’t leave their soldering irons at home. The actually swore their vows by soldering together a circuit during the ceremony (blinky wedding dress, el wire tuxedo, and all).

[Kevin] sent in a link to [Red Fathom’s] hacked Wacom tablet. It’s the screen from a Wacom-enabled laptop brought back to life with a Teensy and an LVDS interface module.

The Neato XV-11 is able to find its charging station when the batteries run low. [Derek] figured out that you can make a second station using some reflective tape.

If you use your drill a lot you’ll eventually break the rubber thing that holds the key to the chuck. Here’s a way to 3D print a replacement.

[Torxe] put eight floppy drives to use as a polyphonic Arduino-controlled MIDI player. And while we’re on the subject of Arduino controlled projects you should take a look at this web-interface to tell you if the foosball table is being used.

And finally [Th3 Bad Wolf] sent in this link to a milling machine built out of LEGO. It is able to mill floral foam and uses a lathe-like setup for one of the table axes.

Measuring the lifespan of LEGO


How many times can you put two LEGO pieces together and take them apart again before they wear out? The answer is 37,112. At least that’s the number established by one test case. [Phillipe Cantin] was interested in this peculiar question so he built the test rig above to measure a LEGO’s lifespan.

The hacked together apparatus is pretty ingenious. It uses two servo motors for testing, each driven by the Arduino which is logging the count on an SD card. One of the two white LEGO parts has been screwed onto an arm of the upper servo. That servo presses down onto the mating piece which is sitting inside that yellow band. Look close and you’ll realize the yellow is the handle end of an IC puller. When the post on the lower servo is moved toward one arm of the puller it grips the lower LEGO piece tightly so that the upper servo can pull the two apart. In addition to the assembly and disassembly step there’s a verification step which raises the mated parts so that a reflectance sensor can verify that they’re holding together. [Phillipe] let the rig run for ten days straight before the pieces failed.

Don’t miss his video description of the project after the break.

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