Archive for December, 2007

Building Tips and Tricks: Pulling Pieces with the Flexible Axle Joiner

Friday, December 28th, 2007

A trick commonly employed in TECHNIC/MINDSTORMS building is using an axle to push another axle (or some other piece) out of a tight spot. I’ve found it helpful to use another trick, however, that involves the flexible axle joiner (see below). The NXT set includes eight of these pieces, and you can actually use them to help pull axles and other pieces out of very tight spots. Unconventional, perhaps, but it works since the flexible axle joiner is rubber, offering more grip than if you were just using your fingers.

Flexible Axle Joiner

Try running a 7M axle through several double cross blocks and split cross blocks and then attempt to pull the axle out. Not that easy, is it? Next, take a flexible axle joiner with two fingers and “grab” the axle as shown in the picture below. Now try to pull the axle out of the cross blocks, aided by the flexible axle joiner. You should find the task much easier. This little example demonstrates how the flexible axle joiner can significantly increase your ability to pull out pieces, such as axles, from difficult areas.

I’ve had great success with this trick, but you should be warned that it could possibly lead to “ripping” your flexible axle joiners. With that said, I’ve never had one of these pieces rip as a result of doing the trick. LEGO pieces are the strongest elements on earth, right?

Using the flexible axle joiner

Claw-Bot Video

Monday, December 24th, 2007

I’ve added video of Claw-Bot, the robot from Chapter 13 of The Unofficial LEGO MINDSTORMS NXT Inventor’s Guide, to the “Pages” section of the blog. You can also watch the video below.

Claw-Bot is based on the Zippy-Bot model from Chapter 11, adding a claw-like subassembly with an ultrasonic sensor and a light sensor. Claw-Bot moves toward the center of the NXT test pad, spins in a circle until it detects an object with its ultrasonic sensor, and then drives forward to push the object until its light sensor detects the black line. The robot is programmed to find three objects, but it’s easy to change the number to more (or less) than three. Go Claw-Bot!

MINDSTORMS NXT Sumo Competition has over 100 entries!

Wednesday, December 19th, 2007

The official MINDSTORMS NXT Sumo competition I mentioned earlier now has 109 entries! You can no longer enter sumo-bots into the competition since the deadline was December 15th, but it’ll be interesting to see the outcome. You can read the official news release here, and you can see all the entries here. The judges will select robots from the entries, build and program the robots, and then hold a sumo match.

That’s one sumo match I’d love to attend. Good luck to all the contestants!

LEGO Digital Designer (LDD) Version 2.3

Friday, December 14th, 2007

Creating building instructions for NXT robots can be a lot of fun. And it’s a great way to “preserve” your robots after you’ve taken them apart. There are now a variety of ways to create virtual NXT robots and building instructions, but a quick and easy way to begin for either Windows or Mac OS X users is with the official and free LEGO Digital Designer (LDD) software. Since the capability to create NXT robots with LDD is relatively new, there are still some bugs to work out. But it does work. Version 2.3 of LDD was recently released, and you can visit to download the latest version.

Note that I did not use LDD to create the building instructions in The Unofficial LEGO MINDSTORMS NXT Inventor’s Guide. Rather, for my book I used a set of tools based on the LDraw system.

LEGO Digital Designer

NXT-G programs from Chapter 8 now available

Tuesday, December 11th, 2007

After receiving an email from a reader who had put together one of the programs shown in Chapter 8, “Advanced NXT-G Programming,” I decided to make the programs available to everyone. Although the programs shown in that chapter were only supposed to clarify the concepts being described (i.e., the reader is not expected to test the programs), experimenting with the programs is fun! You can download them from the following page on the book’s companion website:

Sample NXT-G Program

Bumper-Bot Video

Sunday, December 9th, 2007

I’ve added video of Bumper-Bot, the robot from Chapter 12 of The Unofficial LEGO MINDSTORMS NXT Inventor’s Guide, to the “Pages” section of the blog. You can also watch the video below.

Bumper-Bot is based on the Zippy-Bot model from Chapter 11, adding a bumper built around a single NXT touch sensor. Bumper-Bot is content to explore its surroundings by randomly running into objects and then changing its path. Fortunately, robots don’t get headaches from bumping into objects—unless they’re programmed to get headaches, of course.

Book Signing in Round Rock, TX

Saturday, December 8th, 2007

I’ll be doing a book signing for The Unofficial LEGO MINDSTORMS NXT Inventor’s Guide at a Barnes & Noble store here in Round Rock, Texas. The signing is scheduled for January 12th, 2008 at 2PM. I’ll be bringing two robots with me (probably Tag-Bot and Guard-Bot) to demonstrate some of the robots in the book. So if you live nearby and would like to get a signed book, see some robots, or simply talk with me about the book, come on by!

Here is the address of the Barnes & Noble location where the book signing will be held:

La Frontera Village
2701 Parker Road Bldg A Suite 700
Round Rock, TX 78681


Excerpts from Chapter 4 and 14

Friday, December 7th, 2007

For those who’d like a peek inside The Unofficial LEGO MINDSTORMS NXT Inventor’s Guide, you can read excerpts from Chapters 4 and 14 at the following link:

These two chapters are among my favorites. Chapter 4 covers all the pieces in the NXT set and topics such as, “What do I call the pieces?” and “How do I measure the pieces?” Chapter 14 shows how to build, program, and test Tag-Bot, the robot on the cover.

Golf-Bot Video

Thursday, December 6th, 2007

I’ve added video of Golf-Bot, the robot from Chapter 16 of The Unofficial LEGO MINDSTORMS NXT Inventor’s Guide, to the “Pages” section of the blog. You can also watch the video below. Have you ever seen a LEGO robot golf? This bot scans its surroundings for a special LEGO target, places a ball on the ground (a LEGO ball, of course), and then hits the ball into the target. Despite its size and complexity, Golf-Bot can be created from the pieces in a single NXT set. There’s just not that many pieces left over by the time you’re finished building!

Deadline nearing for MINDSTORMS NXT Sumo Competition

Sunday, December 2nd, 2007

The deadline for entering your NXT sumo-bot (or sumo-bots) in the official MINDSTORMS NXT Sumo Competition is Saturday December 15, 2007. The MINDSTORMS website has hosted a number of contests, but I think this one is the most exciting! If you haven’t already, check out the website to find out the rules and other details; there’s also an extensive FAQ.

Can you create a winning NXT sumo-bot? It’s a tough challenge for sure. The robot will need to push and shove its way to victory!

MINDSTORMS NXT Sumo Competition