BrickEngineer: LEGO Design

LEGO Engineering for LEGO NXT and Robot Enthusiasts

MATLAB Packages for the NXT

There are now several MATLAB packages for robotics, and specifically for the NXT.  One paradigm is to run the code on a PC and have it communicate direct commands to the NXT Brick via Bluetooth or USB.  I have found this paradigm to be a bit dangerous since in the event of a MATLAB crash or a miscommunication, the NXT Brick will continue with its last command until ordered to stop.  This has the potential to destroy your robot.  The paradigm that I prefer to use is to write several programs that run on the brick.  These programs take commands from files on the brick that can be uploaded rapidly from the PC.  The MATLAB code then is in charge of sending the command files and starting and stopping programs.  In the event of a MATLAB crash or communication failure, the software running on the NXT Brick can be designed to terminate gracefully.

Here are the MATLAB packages that I know of.  The first two are specifically geared toward the NXT; whereas the last is a general robotics package.

LEGO Pin and Axle Puller

One of my students recently gave me an idea for a LEGO tool.  This is the LEGO Pin and Axle Puller.  Axle pins and axles themselves are often hard to get out.  At some point everyone has used their teeth, but you damage your LEGOs when you do this; not to mention your teeth!  Pliers do too much damage.  Coating the tips with rubber is a nice trick, but it doesn’t last.  There are plastic grippers, but they don’t grip in the right way to remove these pieces.

So why not make a tool out of LEGOs?

Presenting the LEGO Pin and Axle Puller:

LEGO Pin and Axle Puller

The handle is sturdy enough to apply a reasonable force.  The rubber axle joiners grip axles well without damaging them.  The shock absorber is a nice feature that keeps the tool open, but it is not necessary. Just be sure to use one with a soft spring, rather than a hard spring.  Otherwise, you’ll find yourself working against the spring rather than the part.

The instructions can be found here.

Kevin Knuth

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