Sep 30, 2008

Guitar-Playing NXT

Here's the description from the creator:

"This robot can play five chords using three NXT motors. The guitar is an ordinary acoustic guitar tuned in "open C" - it plays a C chord when the strings are strummed without the other hand touching the fret board.

And I can say that the robot plays the guitar better than I do!"

Bot'oberfest 2008 Summary

Yesterday, over 400 participants gathered at the Atlanta Girls' School for Bot'oberfest 2008 (up from almost 300 in 2007).

Classes this year included:

Intro to NXT-G Programming
Intermediate NXT-G
Advanced NXT-G

Basic Robot Design
Reliable Robot Design
Chassis Design

FLL Project & Judging Overview
FLL Missions Overview (and Discussion of Rules)

Open Meet & Discuss

I'll post a link shortly where you can view slideshows for the various classes. The event was a huge success, and we're already hearing back from attendees on what they liked and what they'd like to see next year. We broke the event up into a morning and afternoon session and allowed participants to sign up for one or the other (the schedule was repeated and the spreadsheet can be downloaded here).

Sep 29, 2008

RHex, the Rugged Robot

Today, I ran over the web site of Boston Dynamics that features a video with a fascinating robot of theirs, the RHex ("The Rugged Robot that Devours Rough Terrain").
It's a six-legged machine that is able to walk over almost any terrain found out there, to climb stairways, steep slopes and railroad tracks and even to swim!

Though it's not a NXT robot, the video decidedly is some kind of inspiration in that regard (however, don't try to throw your brick into a pool of mud, don't you! Mind, it's not as sealed as RHEx...).

Watch the video - it's intriguing!

One-Kit Wonders, an outline

LEGO MINSTORMS NXT One-Kit Wonders, the new book by the blog contributors is scheduled to be printed around the fourth of November this year. This post gives you an outline of the ten chapters and their robots.

Chapter one:
CandyPicker: A candy-picking robot with built-in generator and remote control

Chapter two:
PunchBot: Old-school programming using your NXT

Chapter three:
M: the m&m sorter

Chapter four:
NXT Dragster: The NXT STEP Dragster Challenge

Chapter five:
BobBot: An NXT version of the Bobcat

Chapter six:
RoboLock: A security system for your robots

Chapter seven:
The hand: A robot for those dirty jobs

Chapter eight:
SPC: Self-parking car

Chapter nine:
GrabBot: A robot that finds, grabs, lifts, and moves

Chapter ten:
Bike: A two wheeled, obstacle avoiding vehicle

Read more about the book in previous posts here.

Sep 28, 2008

FLL Anime Overview Video

While exploring the depths of Youtube, I came across this nicely done Anime video discussing the concepts of the FLL competition by a Saudian FLL team.

I think it gets the Gracious Proffesionalism theme across particularly well, and how winning is not everything... just enjoy!

Good luck to all,


Robot Inspiration Series #9: Construction Bots

EDIT : You can see a robot that does this sort of thing here.

This week's inspiration is somewhat advanced: construction robots. Can you make a robot that builds something, on its own, out of LEGOs? It doesn't have to be another robot, or even something very complicated. You could have a robot build a wall, for example. Or you could have a pallet of pieces, arranged in the right order, that a robot selects and puts together on a workspace.

You can see some (very) elaborate examples of construction robots in the Aircraft Factory and Car Factory. Obviously, you probably wouldn't make something like this, but maybe a small, simpler, version would be possible.

Let us know if you make one!


P.S. See other posts in this blog series here.

Sep 27, 2008

NXT Birthday Cake

Shortly after reaching the 50 project milestone, today the web site reached another milestone by turning one year old! So here is a one-candle birthday cake project to celebrate.

The flame on the candle of the cake will "flicker" while the NXT plays the "Happy Birthday" song ,and when the song finishes, you can make a wish and blow out the candle. The sound sensor will detect the blowing, and then the flame will disappear!

Here is a video of the cake in action:

Sep 26, 2008

Building Instructions for Axle/Pin Puller

The rubber axle joiners at the center of the grip are to prevent damage when gripping or pulling parts. Building instructions are here.

Technic Triangles

Kevin Knuth has posted some nice, TECHNIC equilateral triangles of various sizes. His triangles are for a drive system; however, clever folks can find other uses for them as well.

Several of the triangles shown have lists of parts and building instructions here.

Sep 25, 2008

FLL Resources

We enjoy covering FLL and will continue to bring you news related to it, but just in case you're unfamiliar with the site, please check out if you've never paid a visit. Marco Ciavolino's coverage of all things FLL is outstanding - he even provides an email newsletter that always keeps you up-to-date on rule changes, new resources, and anything else he can fit in there... many of the notices you see on our blog related to FLL come directly from Marco. He's recently added some new resources that teams will find incredibly useful... here's a sample of his most recent newsletter:

1. Anne and Dave, our new mentors for FLL, have come up with the most amazing, simple, and effective method for helping a team work through the missions, especially for rookie teams.

Read about it here:

2. New Resource: Three Climate Maps

We found a range of global climate maps. Here's the worksheets we used to generate a huge amount of discussion.

See it here (scroll down to first new item)

3. Two new group communications games.
Check out plural weather terms and marker mystery.

Download them here. Scroll down and look for the two new items.
4. Get personalized versions of the Climate Connections Poster

50 Fun Projects for your NXT

The website reached a milestone recently, with 50 projects posted, all with full building instructions and downloadable programs. To celebrate this milestone, I have published a new version of the CD titled "50 Fun Projects for your LEGO MINDSTORMS NXT", now in a full color jewel case. The CD is useful for anyone who wants to access the projects without a fast internet connection in their LEGO room, as a backup against network flakiness, or just as a nice addition to their collection of books and other NXT resources. A significant bulk discount is also available for teachers and coaches to order multiple copies to use in their classrooms and/or distribute to their students.

Also, by popular demand, I have started to try to enter the video age by posting videos of the projects on YouTube. There are some there now from the most recent projects, and as I have time, I will be rebuilding and videoing the past projects to get more up there.

NXTLog Challenge - Cool Creature Building Challenge

What can be more fun than a barrel full of monkeys? A barrel full of NXT monkeys! We've had Biped, Quadruped, and even Bug Bot challenges on NXTLOG, but now we want you to have lots of fun and build the coolest creature on the planet.

Read on here at NXTLog.
Have fun!


EDIT: Due to a request from a reader, I've changed the link above to a hyperlink.

Robotics Club in India

One of our readers, Mr. Kumaran from India, sent me a nice link about the Robotics Club in Bangalore he is member of. Together with friends of his, they hold Robotics Classes at the Spastics Society of Karnaka.

Visit the site - great stuff!

Sep 24, 2008

Mexican Robotics Tournament 2008 - Guest Blog

Reader MG submitted the following writeup - (be sure to check out the pictures using the Picasa link at bottom):

The Mexican Robotics Federation, the Instituto de Ciencia y Tecnología del Distrito Federal (Institute for Science and Technology of Distrito Federal), along with local private and state universities hosted a national robotics competition, at Palacio de Mineria, from September 4th through 6th in Mexico City. The event gathered students from all over the country, from middle school to graduate students. It was an event that made national news.

This tournament hosted a great number of categories, from the Robocup and Robocup Jr. to the IEEE Latin American Students Robotics Competition. The variety of robots was big, from homebrew to Lego Mindstorms. You could see humanoid robots playing soccer, cleaning robots, arm disarming robots, rescue robots, line followers and much, much more.

I had the privilege of judging the SEK category. There were 12 teams competing, all of the teams designed their robots using Lego Mindstorms (mostly NXTs, just a couple of RCXs). The designs were very creative, some simple, some complex; the principal sensors used were the ultrasonic, light sensor, touch sensor. some robots had to use two NXTs and Bluetooth in order to be autonomous. For more information on the competition rules click here ( The team Lego Troopers from the university of ITAM were the winners for this category.

Winners of the competition were sponsored so they can compete in upcoming international events like RoboCup, Robot Olympiad, the IEEE Latin American Robotics Competition.

This is a link of the SEK (Standard Education Kit) subcategory of the IEEE Latina American Students Robotics category (mainly is my students participation and touring of Mexico City)

Sep 23, 2008

Toys'R'Us Sale

Reader "W" emailed to inform me about Toys'R'Us annual birthday sale (Geoffrey, their mascot)... LEGO is included in the buy 2, get 1 free deal and "W" said the offer goes for NXT kits this year AND is available on-line and in-stores.

I checked out the website and LEGO products are listed as being covered, but no word on in-store - if someone else wants to verify and drop me an email, it'd be appreciated.

Rebuilding LEGO: A Success Story

Here's an admittedly wonkish article about the improvements to LEGO's supply chain in recent years. (After all, we can't rhapsodize about the NXT until we can actually GET the NXT, right?). :)

Some key points of the piece (for those who'd rather pass on the complete article):

Through a series of management moves, LEGO:

1) Reduced its number of vendors and made larger, more regular purchases from each one, enabling it to leverage the company's scale with suppliers.

2) Better coordinated the production within its mold machines, resulting in better utilization and increased capacity.

3) Decreased fulfillment costs at their distribution centers by bundling orders in larger shipments.

4) Rationalized their production cycles into 4-to-12-week increments (instead of making every machine available to produce any element at any time).

5) Relocated its factories near its most important markets (e.g., Europe), thereby decreasing its distribution costs.

All of this means that, when dealing with LEGO, you'll (hopefully) get what you want when you want it.

AlphaRex's RoadTrip to Pisa/Siena, Italy

AlphaRex sure get's around! Find out about his recent visit and view the picture album here.


Other LEGO Blogs

There are many blogs out in the world today. Many are devoted to LEGO topics. Some are devoted to Robotics. But not many are devoted to both LEGO and Robotics.

The Brothers Brick is one of the LEGO Blogs out there. It isn't really Robotics focused, or even Technic focused. It's more of a "Check out this cool creation". They have a good group of authors, and a large readership.

The Brothers Brick recently posted their 10 Other LEGO Blogs you should be reading. And guess who is on the list! That's right. The NXT Step!

One of the other blogs they mentioned looks pretty good too. It's called TechnicBRICKS. They cover a lot of Technic creations, which often go hand-in-hand with the NXT Robotics creations too.

And one last find. The Brothers Brick recently featured a Tripod Turret that is fully automated, and appears to be powered by some PF devices. You can read their writeup here. The Brothers Brick - Auto-Controlled Tripod Turret.

Sep 21, 2008

Scripting to the Screen - NXT-G and nxtRICeditV2

We blogged here a while back about a fantastic utility from Andreas Dreier called nxtRICeditV2, a way to edit the subtle and complex image files used by the NXT. But displaying anything other than simple images under NXT-G really wasn't possible. Now Guy Ziv over at NXTasy has authored a nice block to allow custom fonts, designed with nxtRICeditV2, to be used with NXT-G. Take a look here:

Advanced Display Text NXT-G block

He's done a really nice job on the interface, including built-in help, and included a couple of sample fonts (one with larger characters, one with smaller characters, and one that is upside-down). Take a look and try this out - it should install just fine under v1.1, or under v1.0 with the patch. Let us know how you use these! And thank you Guy Ziv for authoring some nice blocks for those of us who still like using NXT-G.

Brian Davis

Robot Inspiration Series #8: Bionic Apparatus

One interesting kind of robots is bionic robots, or robots that humans can wear to gain extra capabilities. Some examples of these robots are my A27 Bionic Glove and Bionic Helmet.

So this week's inspiration is to build some sort of bionic apparatus that you wear and that gives you one or more extra capabilities. Some examples include extending grabber arms, night vision (or object detection at night), weapons, and decoders (make your own code, like a color code, and a robot that can read and decipher it). Some places to wear a robot include on your arm/wrist, in your pocket, on your leg, and on your back as a backpack.

A couple issues to consider when making a bionic apparatus are fit and weight. With solid, blocky LEGO building pieces, it can be pretty hard to make a robot that fits securely and, especially, comfortably. And by the way, even if the robot seems to have a comfortable fit, wear it around for 10 minutes and you might change your mind! :-) When trying to get the fit right, it can be helpful to use soft, flexible pieces such as tires and other rubber parts. String might also come in handy.

If your robot weighs too much (or if the weight isn't spread evenly throughout the robot), it can be awkward and uncomfortable to wear. Try to keep motors and NXT Bricks to a minimum. You might even be able to wear the NXT Brick separately, such as in your pocket.


P.S. You can see other posts in the Robot Inspiration blog series here.

Worldwide Calendar of Robotic Events

Together with a contact for listing your own robotics event.

Sep 20, 2008

FTC TETRIX Parts Available to the Public

The parts system being used for the FTC competition (besides the NXT), TETRIX, is available to the public on Pitsco's website, here. Although the parts are pretty expensive, this system basically allows you to take your NXT to the next level. 12-volt DC motors and strong aluminum beams and other parts let you build big robots that are still controlled by the NXT Brick. With the motor controllers that allow the NXT to control the non-LEGO motors, you can have many more than three motors; by stringing motor controllers together, you can have almost as many motors as you want, provided you have enough batteries.

One important problem with the Pitsco store is that it doesn't seem to sell the HiTechnic controllers which are required to let the NXT interface with the TETRIX motors. Hopefully these will be available from HiTechnic soon.


New Sensor from HiTechnic

I was just surfing the HiTechnic Website when I found that they have released a new sensor. The Electro Optical Proximity Detector or EOPD is used to ...accurately detect objects and small changes in distance...

The sensor has its own internal light source so it won't be disturbed by external light signals. Objects can be detected from distances up to 30 cm. Has anyone got or tested this sensor - if so please comment and share your experience with the rest of us.


Sep 19, 2008

AlphaRex in the Black Forest

On his trip around the world due to the 10th anniversary of LEGO® MINDSTORMS, AlphaRex has visited the idyllic Black Forest in Germany and I have been able to take some shots - have a look for them at the official LEGO® MINDSTORMS site.

Sep 18, 2008

Tripod II

Here's another Tripod prototype spin-off from the said internal competition, this time created by Mike Brandl. Its name is RAMA, and details (including a movie) can be found on the associated web site (though the text is in German, there are a lot of images also).

"Terminator" NXT Talking Skull

More videos and a complete description are here.

Sep 17, 2008


For an (internal) contest some time ago, some MINDSTORMS veterans took up the challenge to build NXT tripods, i.e., NXT-based robots on three legs that would be able to autonomously walk in arbitrary direction (without rolling) and avoid or cross obstacles.
Though it doesn't look so at a first glance, this is a rather difficult task from the engineerical point of view which might be the reason why so few actual working tribot robots have been built so far.

One of the prototypes that arose from that efforts is that of Philo:

It walks along with a "dragging" movement. More movies can be seen here, pictures are available here, here, here and here.

Sep 16, 2008

The Car That Watches Out for Its Head

Here's a simple but cool model for kids. The creator's description follows:

"This small robot starts with raising its head a little up and keeping it raised because gravity pulls it down. It goes direct until it approaches any thing then it decelerates its speed (so that if it hits that thing, the hit is not hard). Then when it is 25cm far from that thing, it raises its head and turns back randomly either to the right or to the left. The randomness was important to get out from small spaces after many tries."

Sep 13, 2008

LEGO MINDSTORMS NXT One-Kit Wonders, a preview

(Click here for a high quality video.)

Are you curious for the robots in this book? Here's a preview with three models and what else you will find in there. All ten chapters include building instructions as well as detailed programming instructions. In other words, all you need to spend hours of fun with an NXT kit.
Each author will be blogging about his robot design in the coming months. Stay tuned!

Sep 12, 2008

New Book by NXTstep Bloggers

To be published November 29, 2008--just in time for Thanksgiving, Kwanzaa, Hanukkah, Christmas and every budding engineers birthday. :)

Each of the ten models in the book requires only one NXT retail kit. The Amazon link is here.

(NOTE: Amazon has the book listed as "NXT Idea Book Volume 2". However, the book's image on the link has the correct title. The publisher promises to correct this on Amazon as soon as possible).

When Not Building Robots...

I have a LOT of hobbies and prefer to make things by hand when I can - so for my wife's recent birthday I suspected she'd probably like something non-robotic in nature. These were time consuming so I just haven't had much chance to play around with my latest NXT idea (it's coming... soon...) but maybe some of you will enjoy these and try your hand at making one... or two... (they are addictive). I'm working on doing one showing an NXT robot in motion, so stay tuned.

Sep 11, 2008

Update on Bluetooth competition

Remember the post on the MINDSTORMS competition by the Bluetooth Special Interest Group where you should build an interesting NXT robot that uses Bluetooth to communicate with some other Bluetooth-enabled device in some way?
They have extended their deadline for submissions until end of October now and dropped the limitation to contributors aged 21 and over - a wise decision in my eyes.

Thanks to our reader Dirk for the information.

Sep 10, 2008

Today CERN started its LHC.

Today CERN, the European Organization for Nuclear Research, has successfully started its collimators that are used in the tunnel of the Large Hadron Collider or LHC. The LHC is the biggest supercollider in the world and is also be largest machine in the world.

Scientists around the world will be watching closely today when their colleagues in Switzerland flip the switch on what is being touted as the world's grandest experiment in particle physics.

If all goes according to plan, the Large Hadron Collider, a gigantic particle accelerator underground near Geneva, could re-create the very moment 13 billion years ago when scientists believe a tremendous explosion known as the "big bang" created the universe.

"It could be the most exciting thing since Einstein," said Yale Professor Paul Tipton, part of a multinational research team, including physicists at Yale and Fairfield University, that has spent years designing and building the collider.

Now what has that to do with Mindstorms?
Engineers at CERN chose National Instruments products (like Labview) to control the collimators. As many of you know Labview is also the base of the NXT-G programming language....

Read more:
NI video about CERN
Google News on LHC

Stanford Personal Robotics Program

I know this is another OT post, but I want one of these. :)

NXT Step Community and

I try to keep my blog posts as relevant to NXT as possible, so I hope you'll forgive me if I go off topic for a few minutes of your time and tell you about an organization that I support and ask you to consider helping. If you're not familiar with, you can visit them at and learn more about what they do and how they do it.

In a nutshell, though, they take small donations (as little as $25.00) and use the funds to create small "micro-loans" to businesses in poor countries around the world. You make a donation, browse the businesses that are trying to raise funds, and select as many as you want to support. I currently support 5 businesses, and have made donations of anywhere from $25 to $100 to each. Other donors make similar contributions and that's how these small businesses get their loans - usually anywhere from $250 to $5000. Each business is required to make regular payments on their loan and as payments come in, your account is credited back the money that you can either cash out or donate again to more businesses.

As a small business owner myself, I share in this organization's goals and believe that giving someone (or a group) the opportunity to start a business benefits that person, his/her family, and his/her community where the money typically stays in circulation. I'm a HUGE supporter of the "micro" method of raising funds - don't ask 10 people for $5000 each... ask 50,000 for $1.00 each (or in this case, ask 40,000+ blog readers to each contribute $25.00 - that's over 1 MILLION dollars! is making a difference - they are having SUCH success that they've run into a problem! Six months ago, when I first joined Kiva, they had over 200 small businesses in their database for me to select from... today they have completely funded all their small businesses! That's a GOOD problem to have, right? They're working on adding more businesses to their database and have implemented a new feature - Kiva Teams.

I've created a Kiva Team - The NXT Step Community. The NXT Step currently has over 40,000 visitors each month from around the world, and I'd like to see what this group of NXT fans can do when it comes to fund raising. Every dollar goes to - not to me or to the blog. Your money will be credited back to your account as the loan(s) get paid back and you can choose what businesses to fund with your money. Seriously - if every NXT Step reader opens an account and contributes just $25.00 and not another penny, we will have raised over 1 million dollars. I've started the fund with $100.00 (credit - see image of My Portfolio) and will give periodic updates on how our team is doing.

For now, you can simply signup and join The NXT Step Community team. If you like, once you're logged in, click on your "My Portfolio" button and then click on the link "Add Credit" or wait until a business is accepting funding. Once you fund a business (or 2 or 3 or...) you're donation will show up on the Team Page.

Here are the links you need:

Kiva's homepage:

The NXT Step Community Team Page:

Invite your friends and family... ask your employer to make a matching contribution... ask your parents to make a matching contribution... challenge another FLL team to see which team can raise the most funds. (Come to think of it, I'm going to ask LEGO to consider making a matching donation each quarter or each year based on how much we raise! - will keep you informed.)

I want to thank all of The NXT Step readers for your your support of the blog.

Sep 9, 2008

Nice GBC from Euskadi

Koldo from Euskadi (Basque Country) hinted me to his MINDSTORMS-related web site that contains a nice video on a GBC that he created together with his son:

The modules might be part of a GBC that will assembled on the 2nd Hispabrick that is going to take place in Barcelona on 6th and 7th of December 2008.

Sep 7, 2008

NXT Baudot Machine

Once the marvel of modern communications technology, Baudot was the high speed internet of its day, now its sadly neglected. But by using the power of LEGO you too can now re-live this wonder of wireless telegraphy.

Explanatory notes can be found here:

Constructopedia 2.1

This past June, updated their "2.0" manual of NXT building instructions, showing basic construction techniques for beginning builders.

The download page for Constructopedia 2.1 is here.

FLL assistance at


Yesterday (Friday) almost 1000 unique visitors from all over the world downloaded about 6000 documents from We received many enouraging comments. Thank you!
This week teams all over the world will be meeting to evaulate the Climate Connections missions. You'll want to show the mission videos.

We've converted the 'All Missions' Flash movie to WMV so you can play it on your local computer and project it if necessary.

You can download it here...
Your teams can watch individual videos online at:

Sep 6, 2008

FLL Climate Connections Challenge Details Announced

See the FLL Home Page for Project and Robot Game details. The Robot Game also has video examples included with each mission description.

AlphaRex in Salzburg (Austria)

During his travels around the world on the occasion of LEGO® MINDSTORMS' 10th anniversary, AlphaRex has made station at Salzburg, the famous Mozart city in Austria.

Sep 5, 2008

NXT Mouse Trap

You know the old saying, "Build a better mouse trap...". Well, this NXT Mouse Trap tries to continue in the tradition of the classic spring mouse trap, by snapping closed when the mouse steps on the plate with the bait on it. But having a motor and NXT brain, this improved trap can automatically reset itself if it misses or if the mouse escapes. Maybe you will think of something better still, using more sensors, or maybe using an entirely different strategy...

Here is a video of the trap in action:

Sep 4, 2008

Botoberfest 2008 Registration

Better late than never, right?

Click here to be taken to the registration site - preference for filling classes will be given to registered teams, so be certain to include your team # and list the names of those members attending please.

Email link:

NXT nibblets

I keep ending up with a list of things to mention, but not enough time to do it (or not enough material for a full post), so here's a brief roundup of a few things. So in no particular order...

The HALE mission has put out a nice YouTube video, showcasing some of the video as well as the still photos from the ground team end of the mission. It also gives (at the end) a run-down of some of the faces & names involved. Take a look, and enjoy the music & presentation.

HALE YouTube Mission

Steve Hassenplug has come up with a novel robotics game he's named "PSumo" (for "programmable sumo"). The idea isn't to make fantastically complicated or fast sumo robots, but instead to make a series of nearly equal robots that casual observers can "program" by using RFID cards swiped by a sensor on the robot. It was a huge hit at the recent Brickfair event on the east coast, and I'm sure we'll see it a lot of other places. We'll probably have a detailed blog post on this soon.

PSumo from Steve Hassneplug

A number of people have asked for plans or more details on my recent PnP arm, wanting to duplicate it or at least understand it better. While the odd, very-non-rectangular geometry makes it difficult to reproduce in LDD, I did do the arm itself and a partial attempt at a loading pallet. I've put those up along with some images and a stripped-down NXT-G program & video up on NXTlog, for anyone who wants to try it. Let us know what you do with it.

PnP on NXTlog

Here's a novel physics demonstration (hey, I'm a physicist, what did you expect) of non-linear resonance. Want to make a pendulum stand up the wrong way? Vibrate the support point fast enough, and you get an interesting effect...

Vertically driven pendulum

Finally, what do you get when you couple something like Jim's camera platform with heavy metal? A camera panohead that looks like the NXT was grafted on to a butchered store display frame, but it works :).

PanoKong on YouTube

Brian Davis

Sep 3, 2008

NXT Amusement Park Ride - Free Fall

Reader Dino pointed me to one of his very interesting designs - a freefall for minifigs... read all the details here.

Robot Building Contest from Bluetooth SIG

Reader Alex from the Bluetooth Special Interest Group emailed the following:

The Bluetooth Special Interest Group has launched a competition for fans to design a robot from the Lego Mindstorms NXT kit that uses Bluetooth technology to connect to other devices like mobile phones or PC’s.

Using components available from the NXT kit (and also creative additions if you like), all you need to do is capture your robot on video with its Bluetooth capabilities in action. The most impressive entry wins the competition, which has cool Bluetooth products for prizes.

More information here

The Armored Car by Leonardo da Vinci

In course of preparations for the 10th anniversary of LEGO® MINDSTORMS I've rebuilt Leonardo da Vinci's Armored Car from my book "Advanced NXT: The daVinci Inventions Book" (Apress 2007) and created a movie on it:

Sep 2, 2008

Sundial Robot - Guest Blog

Reader DTAAX submitted the following:

After building a robot that fired Bionicle balls at a light, my son suggested I use the same platform to build a Sundial Robot. The robot uses the NXT brick, 3 motors, Compass Sensor, Light Sensor, Touch Sensor and ~270 other parts. Three non-standard parts are used: The big wheel from the Star Wars Hailfire set, a cardboard tube to enclose the light sensor, and a PDA. The PDA is used to perform the trigonometric calculations required (because I was too lazy to implement trigonmetric functions on the NXT). In operation, the robot rotates 360 degrees to calibrate the Compass Sensor. It then rotates in 5 degree increments, the light sensor is swept from vertical until the Touch Sensor is pushed. During the sweep the maximum light level seen is recorded. Once the robot rotates from 70 to 270 degrees magnetic, the NXT sends via bluetooth the magnetic heading where the maximum light level was seen. The PDA then calculates the time and sends the result to the NXT. The NXT then sets the clock to the time. In practice, the robot is accurate to within 15 minutes or so.

Sep 1, 2008

Self Stabilizing Chimney Climber

The first RCX climber was slow and unbalanced. The second NXT version was much faster, but still not very stable since it used the same techniques. This third version is a new design, made so that it will automatically balance itself on one axis. Balance on the other axis is achieved with an acceleration sensor.
Imagine a line from the left wheels to the right wheels, through the middle of the robot. On this line, the robot tilts when it gets unbalanced. Unlike in the older versions, the main weight is now below this line. This means that it will keep itself balanced without help.
However, there is another possibility for the climber to crash. That happens when either of the sides loses a bit of grip or if both sides do not go as fast as each other. You can correct this error by making one of the sides go slower, so it will achieve balance again. You would only have to know how big the error is, and in what direction. This is what the Mindsensors Acceleration sensor measures. A relatively simple NXT-G program keeps track of the sensor and motor speeds. It goes up until it sees the ceiling and then comes down again.

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