I Am NXT 3-Point Bend Tester. Please Insert Girder.

Learning with visuals can be very helpful.  Learning with models made from NXT Mindstorms is just plain awesome, as [Rdsprm] demonstrates with this LEGO NXT 3-point bend tester that he built to introduce freshmen to flexural deflection and material properties. Specifically, it calculates Young’s modulus using the applied force of a spring and the beam’s deflection. [Rdsprm] provides a thorough explanation in the About section of the YouTube video linked above, but the reddit comments are definitely a value-add.

[Rdsprm] built this from the Mindstorms education base set (9797) and the education resource set (9648). Each contestant endures a 5-test battery and should produce the same result each time. The motor in the foreground sets the testing length of the beam, and the second motor pulls the spring down using a gearbox and chain.

This method of deflection testing is unconventional, as [Rdsprm] explains. Usually, the beam is loaded incrementally, with deflection measured at each loading state. Here, the beam is loaded continuously. Vertical deflection is measured with a light sensor that reads a bar code scale on the beam as it passes by. The spring position is calculated and used to determine the applied force.

[Rdsprm] analysed the fluctuation in GNU Octave and has graphs of the light sensor readings and force-deflection. No beams to bend with your Mindstorms? You could make this Ruzzle player instead.

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Flocking Behavior Using Mindstorm Robots


Do you ever wonder why geese always fly together in a V-shape? We’re not asking about the fact that it makes the work load much less for all but the lead goose. We mean how is it that all geese know to form up like this? It’s is the act of flocking, and it’s long been a subject of fascination when it comes to robotics. [Scott Snowden] researched the topic while working on his degree a few years ago. Above you can see the demonstration of the behavior using LEGO Mindstorm robots. That’s certainly interesting and you’ll want to check out the video after the break. But his offering doesn’t end with the demo. He also posted a huge article about his work that will provide days of fascinating reading.

We can’t begin to scratch the surface of all that he covers, but we can give you a quick primer on his Mindstorm (NXT) setup. He uses these three bots along with a central brick (the computer part of the NXT hardware) which communicates with them. This lets him use a wide range of powerful tools like MatLab and Processing to recognize each robot with a top-down camera, passing it data based on info harvested with computer vision. From there it’s a wild ride of modeling the behavior as a set of algorithms.

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LEGO LP Player

This LP player is made entirely out of LEGO parts. It plays the songs encoded on each record, but not by using a stylus in a groove. Instead, each LP has a color code on the bottom of it which is interpreted by the optical sensors underneath.

In addition to its functionality [Anika Vuurzoon] made sure that the build looked the part. The horn is a nice touch, but you’ll also appreciate the rotating mini-figures on the front side of the base. To the right there is a hidden door that provides access to the NXT brick which drives the system. New records are produced using a couple of different tools. First off, the song is written using Finale, a mature musical notation program. That is exported and run through a second program which produces the colored disc design which is applied to the records. You can hear the songs for yourself in the clip after the break.

If LP playing toys are right up your alley you’ll want to check out this 3D printed record hack for a Fisher Price toy.

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LEGO ROV Without A Tether

[Brane] built an underwater ROV from LEGO mindstorm parts. Look closely at this image and you should notice something missing. The tether that normally carries power and control lines from an ROV to the surface is missing. This is a wireless solution that lets him control the device using an Xbox controller.

The video after the break shows about five minutes of test drive footage. [Brane] has a big aquarium in which he can test the thing. Since he put it together as his senior engineering project at University it’s likely that this is a testing facility at the school. Here’s the little we know about the hardware: It’s using NXT Mindstorm parts to control the motors, with a sealed chamber for a battery. Connectivity is provided by an XBee module with an NXT adapter board called the NXTBee. A laptop with its own XBee module makes up the other end of communications. Right now [Brane] uses an Xbox controller connected to the laptop, but a standalone device would be easy to build by hacking the XBee and controller together directly.

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NXT Android Telepresence Robot

Here is a telepresence robot that uses an Android device and LEGO NXT parts. [Wolfgang] had an extra phone on hand and decided to put it to good use. The Mindstorm parts make it really easy to produce a small robot, and adding the phone really ups the computing and connectivity options available to him.

The Android device is able to control the NXT bot via Bluetooth. [Wolfgang] didn’t go into detail on that part, but you can get some pointers on the topic from this other Android controlled Mindstorm project. [Wolfgang] wanted the ability to check in at home when he’s travelling. He uses nanohttpd on the Android device to serve up a simple web interface. It uses HTML5 to push a snapshot from the phone’s camera as user feedback, and provides a set of directional arrows which let him drive the bot around.

Obviously this thing is going to run out of juice if he’s away for too long. To combat that problem he included a battery which powers both the NXT parts and the phone. Now he just needs to build an inductive charging station and he’ll really be set.

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My First Robot: A Simple Demo To Get Kids Excited About Robotics


[Will] from Revolt Lab needed a project to get the summer campers he supervises interested in electronics, but when your audience is 5 years old, your subject matter had better be simple, yet interesting enough to hold their attention at length. He settled on using a Lego NXT robot to keep their little minds engaged, because who doesn’t like robots?

He picked up a basic Lego NXT kit and paged through the manual. The first “example” robot looked pretty cool so he decided to give it a shot, though he still hadn’t figured out exactly what he would have the robot do. Inspiration struck, and he decided that he could take advantage of the NXT’s color sensor as well as its proximity sensor to construct a balloon hunting robot.

He constructed a “balloon corral” to keep the balloons in place and the kids out of his thumbtack-wielding robot’s reach. He let his creation loose, and as you can see in the video below, the robot hunts down the blue balloon and pops it, much to the children’s delight.

If you’re in the position to introduce a group of young kids to electronics, this balloon popping robot paired with some conductive Play Dough would make for a fun and educational afternoon workshop.

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LEGO Mill Produces Sculpted Models With Fantastic Resolution

[Arthur Sacek] has really got something with the 3D Mill he built entirely from LEGO pieces. As you can see, it uses NXT parts to control the cutter head along three axes. The drill bit that acts as the mill’s cutting head is not a LEGO part, but that’s [Arthur’s] only transgression.

The demo sculpture seen above was cut into a block of floral foam. The model was processed by Autodesk Softimage before being fed into the mill, where it took about two and half hours to complete the job. The foam comes out still in block form looking like a piece of outdoor carpeting. That’s because there’s no debris removal during the milling process. But hit it with the shopvac and you’ll reveal a physical model with surprising detail. We don’t think it comes close to the light-cured resin printing we’ve seen, but it would be a great asset if you’re doing some mold making.

Don’t miss [Arthur’s] video of the milling process after the break.

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