Sep 30, 2007

Random Page Feature on for "NXT Idea Book" now has a "Random Page" feature for the "NXT Idea Book". (This is different from the "Search Inside" feature).

On two different days of using this feature, I was able to access 35 different pages from the book. (The pages apparently change day-by-day. I don't know how many total pages are randomized).

This is a good way to see additional book excerpts online. To access the random page feature, go here and scroll down to the "Inside This Book" subheading. Then, click on the "Surprise Me" link.

Cirque de Sciences: NXT in Luxembourg

Claude Baumann from a Luxembourgian robot team has published some NXT-related photos from the Cirque de Sciences that took place in Luxembourg on 21st and 22nd of September.
Not only some prominent NXT creations could be seen there, but also some contributors to this blog.


Sep 28, 2007

Something different

Will Gorman emailed me about his new NXT design.

I'm speechless ;)


RoboFest Hawaii

Looks like Bot'oberfest in Atlanta isn't the only NXT gathering in the Fall... Gary in Hawaii sent me the following:

The Second Annual RoboFest Hawaii robotics competition and engineering fair will be held on Saturday, November 17 from 10:00 am to 2:00 pm at the University of Hawaii at Hilo Gym. RoboFest Hawaii is a high-technology and engineering fair thinly disguised as a robotics festival, with competition events for Lego Mindstorms and open robotics platforms. Amid the excitement of the robotics displays and competition will be hands-on, minds-on exhibits from high school engineering academies, community colleges and universities, and high-tech industry. Visit the robotics discovery stations that invite you to build your own robot or underwater ROV. Learn about robotics programs in the schools and community centers, and how you can get involved!
RoboFest Hawaii is free and open to the public, and is a production of AstroDay Institute, with support from Hawaii Electric Light Company and the University of Hawaii Institute for Astronomy. For more information, please visit, call or email him at

18 year old and Data Logging

This month's WIRED magazine has an outstanding article on an 18 year old race car driver who uses Data Logging to help improve his performance on the track. How successful has he been? Well, he just got signed to a NASCAR team...

Read it here.

From race cars to robots, data logging seems to be a hot topic right now.

FLL scoring help

Reader Thomas Johnson has posted a free FLL competition scoring application he's developed. Thomas says it's to help other teams because this years scoring is somewhat confusing/complicated.

You can check it out and download here. Please provide some feedback if you do use it - thanks!

UPDATE: A scoring spreadsheet is also available here.

Sep 27, 2007

SpaceNavigator - another input device for the NXT?

I'd not heard of the SpaceNavigator before, but it looks like a nifty little (and I do mean little) device. Looking like a control knob in search of a mounting panel, it offers 6 degrees of freedom, far more than the NXT currently offers. While it is marketed as a tool for #D animation and CAD, it clearly could have a second life as very compact gaming controller, or in this case as a remote control for an NXT. Over on the ToxicSoftware blog Jon has written a little OSX code to allow his laptop with the SpaceNavigator attached to control his teams FLL robot - take a look at his blog post here, and he announced it over in the NXTasy forums. Not bad at all, and it seems very promising (now, could I have a version of it that is BT wireless from the git-go, and I could dispense with the laptop?). Has anybody else played with this little device? It should be very interesting seeing where Jon can end up taking this - he mentions making the code open-source. Take a look at a video of him controling his robot here (ignore the fact that the poor guy drives over his own keyboard).

Brian Davis

Guest Post - Steve Hassenplug

Steve Hassenplug ( has an interesting little item to share. FLL competitors - take note:


I know this blog usually addresses the LEGO MINDSTORMS NXT, so please bear with me, while I describe a recent event involving a LEGO RCX (predecessor to the NXT).

I just got back from Robothon in Seattle. It was a very fun event. It's always great to hang out with builders who really appreciate each other's robots.

One of the competitions was the Micromouse maze event. In this event, a robot has to navigate through a maze, as fast aspossible. I have a robot that will very reliably get through a maze,if it can simply follow a wall (see Right-Hand or Left-Hand rule), however, one major challenge in a Micromouse event is that the end of the maze can not be reached by simply following the wall. I won't go into all the details about how to solve a maze, but that is an excellent topic for readers to research.

[NOTE: Steve has shared a version of the robot - not the latest, but close here.]

I planned on taking my old reliable robot (called A-Mazing) even though I know there's no possible way it can make it through the maze. Then I had a really interesting idea. Instead of just following the wall all the time, every once in a while (I picked every 30 seconds) the robot would turn 180 degrees, and start following the wall on the opposite side. You may need to draw out some mazes to see exactly what the result of this would be, but it turns out the robot goes from a zero percent chance of getting through the maze, to something greater than zero. Yes, it's much like going through a maze blindfolded, with no real pattern for getting through. But, as it turns out, with a good idea, and more luck than you can calculate, anything could happen.

And, to my surprise, it actually worked. The robot wandered throughthe maze for 30 seconds, and at EXACTLY the right time, made a random turn, which led to the middle (finish) of the maze. The robot went from start to finish in about 45 seconds. That's a far cry from the 17 seconds the winning robot took to finish, but good enough for second place.

I'm not sure I can explain how lucky that timing was. There was a window of about 2 seconds, where the robot could make that turn. Sure, if it missed, it could wander through the maze for several minutes, and maybe get to the end, or maybe not. But, in this case, it worked.

Sometimes, luck plays an important role in robotics. Usually, it's bad luck. But not always!

Sep 26, 2007

Fay's new NXT book

Our very own Fay Rhodes has her first NXT book being released in February 2005 - "The LEGO MINDSTORMS NXT Zoo!: A Kid-Friendly Guide to Building Animals with the NXT Robotics System." I have seen almost all of her 9 robots for this book and I can tell you that the younger NXT crowd AND teachers are going to love this book. Here's the link:

The book's description: LEGO MINDSTORMS NXT Zoo! offers step-by-step instructions for building nine animal robots with the NXT Robotics System. Using the book's detailed building and programming instructions, kids (and their parents) are introduced to the MINDSTORMS NXT kit as they build animal-like models of a rabbit, spider, peacock, stegosaurus, and more! But these models don't just sit there-they walk, crawl, hop, and roll. The book will also show you how to make the models sound like the real animals that inspired them. Troubleshooting tips help builders avoid common pitfalls and parts lists make sure they have everything they need before building. An appendix includes ideas for teachers using these models in the classroom.

The War of The Worlds - a tripod robot

New Scientist has published an article on a tripedal robot - it "walks" in a rather unconventional way by swinging its entire body upside-down with each stride.

Have a look - the video is fun to behold.

This may serve as an inspiration for another LEGO walker...

HiTechnic IR-Link sensor for MINDSTORMS NXT

HiTechnic is just about to launch their new IR-Link sensor.

For more details about the IR-Link, checkout the full review of it in BrickJournal #9.

For many people with legacy MINDSTORMS RCX bricks, the new product will enable creation of robots with both an RCX and NXT that communicate with each other.

For some it will be a means of automating and controlling various home appliances in the house from NXT by mimicking their Infra red remote control. See comments under this post from early this year.

However, for me the most interesting thing about the new HiTechnic IR-Link sensor is how it can be used for robotizing LEGO TECHNIC creations.

The picture below shows a bulldozer 'robototized' by adding a MINDSTORMS NXT brick and a NXT IR-Link (made by HiTechnic) to a TECHNIC bulldozer 8275.

In the video below, you can see it scanning the environment with the Ultrasonic sensors and then flattening anything in its path using the Ripper and the blade:

If you want to learn how to robotize your own LEGO TECHNIC creations with NXT, Power function motors and the new IR-Link, checkout the following video:


Resource for Educators Who Use the NXT

The Tufts University Center for Engineering Educational Outreach (CEEO), located in Medford, MA, provides programs and workshops for teachers and youth who use either the NXT or the RCX version of LEGO MINDSTORMS.

The center provides a summer program for youth in 3rd-5th grades, as well as workshops for educators.

Educators who attend CEEO workshops will:

- Learn about the Engineering Design Process
- Learn LEGO building techniques
- Learn about programming with ROBOLAB or NXT-G
- Participate in hands-on activities such as fractions and graphing.
- Explore Gearing and Gear Ratios
- Explore the pedagogy of using hands-on engineering projects
- Investigate how to teach content through engineering based projects
- Discuss and develop classroom management strategies

The center also sponsors an engineering symposium for Educators who use LEGO MINDSTORMS in the classroom. Below is an outline of the next symposium in Massachusetts, which is still accepting registrants. (Click on the graphic for an enlarged view):

The center also co-sponsors conferences on engineering education throughout the US, as well as in Europe and Japan. For a complete listing of upcoming conferences, click here.

Below are two photos of Robert Rasmussen, the director of the center. The second photo shows Mr. Rasmussen in the center’s “Building Room”. (Click on each photo for an enlarged view).

More information about the center and its programs is here.

NXT Robotics Competition Workbook

Jim and I have been working for a couple months on a new book which we've just released - the NXT Robotics Competition Workbook. Combining Jim's experience as an FLL judge and coach of robotics activities for kids, and my experience of being on a new FLL team which won the Robot Performance and Innovative Robot awards at the World Festival, we've written a 93 page hands-on guide to help both new and experienced teams have a better performance in their competition. From forming good team structure, to building and programming a competition robot, to brainstorming and testing problems, we try to give teams a little bit of everything. A few of the chapters include:

Assigning Team Roles: This chapter gives advice on assigning team roles to members - from Team Captain to Robot Recovery Manager, it's helpful to give memebrs specific responsibilities to make sure everything gets done smoothly and efficiently.

Designing the Chassis: Most robots start with a chassis, so this chapter gives several tips on making one that gives your robot the mobility and accuracy it needs.

Sensor vs. Motor Navigation: With the built-in rotation sensors, programming your robot's navigation purely with motor commands is sometimes a good strategy. But sensors are also great for making your robot more accurate. This chapter gives advice on when to use the different methods, as well as the pros and cons of each.

Brainstorming Sessions: It's helpful to have team brainstorming sessions when working on a challenge or trying to solve a challenge. This chapter gives lots of advice on how to run these sessions and make them successful.

The Worksheets: At the back of the book are 10 worksheets the team can use to help organize their thoughts, make decisions, make a time budget, keep track of programs, and much more! These sheets are what makes this a hands-on workbook.

Here is the Outline for the workbook:

I. Introduction

II. Managing the Team
a. Assigning Team Roles - Organizing Building and Programming Teams
b. Scheduling - developing a realistic schedule, 6 Tasks to get a team from start to finish

III. Constructing a Competition Robot
a. Good Construction Habits - documenting, cloning, inventorying your supplies
b. Designing the Chassis - developing a modular and stable base for your robot
c. Building Attachments - sensor usage, best locations, "funnels" and modularization

IV. Programming the Competition Robot
a. Sensor versus Motor Navigation - pros and cons of different methods for movement
b. Good Programming Habits - backups, version control, filenaming

V. Miscellaneous
a. Brainstorming Sessions - rules, documentation, time limits, getting started
b. Testing Your Work - incremental testing, guidelines for documenting, bug tracking
c. Building Team Unity - respect, team values, sharing

VI. Worksheets
a. 10 worksheets (permission to reproduce worksheets for use by your team)
b. Worksheet titles include "Manage Team 1", "Manage Team 2", "Team Time Availability", "Time Log", "Chassis Guidelines", "Chassis Sketchpad", "Program Tracking", "Elements of the Program", "Brainstorm Session" and "Testing"

You can find the Workbook on our Cafepress Storefront, under Workbooks.


Sep 25, 2007

New PDF book from Japan

ISOGAWA Yoshihito, author of "The Orange Book" (OB)has a new PDF book coming out on October 1. Unlike the OB, this book has very little text (only 3 pages to be exact) but over 200 pages of mechanisms (a nice mix of small, medium, and large) built from LEGO and Technic parts, including NXT components and the new Power Functions motors. It's all in full-color and he's asking for those who download the book and find it useful to contribute $10.00.

I'm including some screenshots here of a few of the 211 pages. There are some amazing designs here and I'm having a hard time picking which ones to use as examples. The book does not require the reader to speak or read Japanese and all 211 demo pages are fairly easy to figure out and duplicate.

FLL teams are sure to find some great examples for inspiration. The sheer amount of work put into these mechanisms is amazing and I highly encourage those of you who do download and enjoy the book to contribute - this will allow Yoshihito to continue developing more books and reference material.

More details will be provided when the book becomes available for download and purchase.

FLL Mission Overview Part 4 - Power Plant Supply

Objective: Move several types of "fuel" on the mat to the Power Plant's property (enclosed by road).

Point Worth: 10 points each for a maximum of two trees in the property, under the condition that another tree has been "planted", 10 points for at least half the load of black coal in the property, 10 points for each green uranium, 5 points for each white oil barrel. Maximum of 85 points.

Mission Location: Near top-right (North-East) corner of mat.

Estimated Difficulty Level: 4/10

Time Length Rating: Medium

Unique Challenge Aspects: Only mission which you can lose points by completing fully.

This mission is probably one of the strangest this year. That's because doing two of the deliveries in this challenge won't give you any extra points, but one of them will in fact decrease your points! You can push the trees anywhere north of the main river to count 10 points each, or you could try to get them all the way to the north edge of the mat, into the Power Plant's property to get...well... the same amount of points. Oh, and you would still have to push one of the trees north of the main river to count as planted, anyway. :P The Oil Barrels are even worse. You could just keep the Oil Barrels in base and get 10 points for each. But if you wanted, you could have your robot push them all the way across the mat into the Power Plant's property... and get 5 less points for each! Unfortunately you're not allowed to move the red oil barrels to the property, so you're stuck with 10 points for each of those. :-)

Anyway, this mission's difficulty is rated at 4/10 because it should be fairly easy to push the deliverables to the Power Plant with the robot, but there is some amount of accuracy required and you do need to push several models.


NOTICE: All of these mission overviews can be found by searching for "Mission Overview" or "FLL Overview".

Richard's Comments: Just wanted to remind everyone that the trees and the windmill must be upright. And I must say, those windmills are really topheavy, so watch out!

Bot'Oberfest in Atlanta! October 14, 2007

More details will be posted shortly on how to sign up for classes, but I wanted to make the draft schedule available for those of you are planning on attending. I'm including links below for 2 documents:

1. PDF containing the schedule (*subject to change*)

2. Course Descriptions (not 100% completed, but we're working on it)

Each of these documents is a zip file.

Feel free to post questions here (as comments) and we'll do our best to answer them.

UPDATE: We've also added a special area in our forum where we can respond to questions and discussions can be held. View it here.

It's a BYOL (Bring your own Laptop and charger). Extension cords and power power strips will be provided.

After the gathering ends at approximately 6pm, we are asking all participants to stick around for 10-20 minutes to help us cleanup (basically putting up chairs, moving tables, etc - easy stuff, especially if we have a large enough group to help out).

The Atlanta Girls' School is hosting the event, October 14, 2007 from 2pm to 6pm. Hope to see you there!

"Double Stamps" Offered At LEGO Mall Stores in US

For the rest of September, LEGO mall stores are offering "double stamp" credit for purchases made at these stores. For a frame of reference, this is roughly $45 in store credit for each NXT retail set that you buy.

More details are here.

Sep 24, 2007

15 LEGO Storage Options

I quite liked this comprehensive collection of LEGO storage options...

It took me a while to get my kits sorted, but I'm now very happily using the ZAG/Stanley organisers described previously by Peter Hoh and Jim Kelly all those months ago...

Challenge Difficulty Levels

I have enjoyed reading Jonathan and Richard's posts summarizing a few of the FLL challenges. Specifically, I like that they are providing "Speculated Difficulty Levels". Here are some questions that might be fun for us to discuss:

What defines an easy challenge?

What factors combine to create a difficult challenge?

If you were designing the 2008 FLL Challenge, what types of missions would you add to challenge teams?

Sep 23, 2007

FLL Mission Overview Part 3 - Hydro-Dam

Objective: Place the Dam - while keeping the Dam upright - so it is touching both banks of any river east of (to the right of) Base.

Point Worth: 25 points, 10 point deduction if the Dam or the projected Flood (more on that later) touches any houses

Mission Location: East (right) of Base

Speculated Difficulty Level: 1/10 for taking the deduction, 1.5/10 for maximum points

Time Length Rating: Low

Unique Challenge Aspects: What's interesting about this mission is that the Referee has to 'project' a Flood upstream from the Dam by placing the LEGO Flood North of the Dam at the end of the match. This calls for quite a degree of accuracy because the robot has to take into account the following: 1) The Dam can't touch any houses, 2) The Flood has to be able to be put next to the Dam (so no shoving the Dam against the wall!)*, 3) The Flood can't touch any houses, and 4) Can't get in the way of any solving any other missions.
Also, the Dam is never a 'Stray Object', so the Referee cannot move the Dam for you to an equivalent scoring position. Rats!

Good luck!

*Edit 9/22/07: Per Q and A #1, you are allowed to put the Dam against the wall. The ref will estimate if the Flood had hit any houses.

Jonathan's Comments: Notice that, for this mission, the model can be placed in a wide range of positions. Specifically, it can be put anywhere along either of the two rivers east of base (provided that it touches both banks of the river). This gives teams a lot of choice in how they do this mission. Of course, if you put the Dam on the south river, it won't score extra points if the Electrical Line model is touching the community next to the north river, so that's definitely something to take into consideration.

Sep 22, 2007

FLL Deadline looming

LEGO Education has posted a reminder on their blog that FLL team registration is almost over... they currently have 5,626 teams registered and the cutoff is 6700!

Read the reminder here or visit the registration site here.

Vernier Sensors - An Update

Kirk Backstrom wrote a bit about the Vernier adapter a few days ago.

I recently was visiting the Vernier website, and found a list (with lots of links) of the sensors that are available.

There are over 30 of them. Here is the list of Vernier Sensors that can be used.

Vernier has sensors to check barometric pressure, acceleration, pH and Oxygen sensors, UVA, gas pressure and many more. The sensors will work with LabView or the Mindstorms NXT software. There is only 1 download block are a few download blocks to add (plus you need to buy the sensors), but this is a great addition to the NXT sensor world!

Sep 21, 2007

LEGO Robotics Workshop

I recently attended a Robotics Workshop put on by Maine Robotics. The course was paid for via some grants that Maine Robotics has secured, so there were no entry fees. Maine Robotics is a non-profit organization run by Tom Bickford that helps promotes robotics in the state of Maine. They coordinate and run the FLL Competitions (in December for us here in Maine).

The workshop was pretty good. It gave some examples of the differences between the RCX and the NXT. Tom also gave an overview of the Robolab software (for the RCX) and the NXT-G language. Seeing 20 or so RCX kits, and 10 NXT kits (plus all the related parts) sitting on one table was a sight to behold. It was like… nirvana… But hey, I digress.

One of my favorite parts, was the overview of the Power Puzzle challenge. I am not coaching a competing team this year, so this was the first time I got to see the playing field up close. After seeing the challenges, and discussing them with a bunch of adults, all I can say is "WOW". I think this is going to be a good challenge this year. Lots of options for points, and many ways to approach and complete the challenges.

I came away from the workshop feeling that there were not a lot of curriculum choices out there for teachers. I know there are a couple of courses, but many of them are expensive, and almost all are geared towards the RCX. Some of the teachers were choosing the RCX as the basis for their course, simply because they can find curriculum easier.

If you're a teacher, what are you using for curriculum?

What would you like to see for curriculum?

Teaching RobotC for Mindstorms

The Robotics Academy at Carnegie Mellon University has released new CD ROM-based curriculum titled Teaching RobotC for Mindstorms. This curriculum is an update to the C-Based Educator that includes coverage of the NXT. Some of the new materials include chapters on:

  • Thinking about programming
  • Speed and control
  • PID control
  • Sensors
  • Variables/passing parameters

The training videos will teach the new programmer step-by-step how to program in C using all of the power built into the new LEGO NXT. (This product also works with the RCX.) Included are:

  • 53 videos
  • Over 300 pages of printable PDFs
  • Over 30 example programs

Review Teaching ROBOTC for Mindstorms at You can also get more information on RobotC at

New NXT Concerto, Using Twelve NXT Bricks

Flemming Sorensen says this about his new creation:

"Five (bricks) provide a steady tone and one brick works as melody master. Six bricks are melody slaves. The melody master flashes two bulbs every 12th note. The slaves see the flash using a light sensor and synchronize to the master."

(The NXT part of the concerto starts about one minute and forty-five seconds from the end of the video).

Sep 20, 2007

Mexican NXT Blog

mgarduno, a reader of our blog, pointed us to another Spanish-speaking NXT blog, Lego Mindstorms en la UABC. It's from Mexico and mainly maintained by the UABC LEGO Team.

Te esperan.

Mindsensors NXT Camera Demos

The video below claims that the NXT camera from Mindsensors will be available by the end of this month. ( makes the same claim). There have been delays with this camera before, so hopefully this claim is correct.

Here's another video of the camera tracking a ball:

Sep 18, 2007

Step-by-step instructions for Java on the NXT

Some guys from the Eindhoven University of Technology have created a tutorial that provides step-by-step instructions for the installation and configuration of leJOS NXJ. leJOS NXJ is a Java platform that enables you to write Java programs for the LEGO MINDSTORMS NXT and run them on the brick.
The tutorial also shows how to use the popular IDE Eclipse for that.

Hence, if you are into Object Oriented Programming when it comes to your NXT, check it out.

Thanks, Christoph and Hu!

Behind the scene look at LEGO® TECHNIC design process

I have spent a big part of this month robotizing the new LEGO® TECHNIC bulldozer that came out early this month. My children and I have had great fun adding a LEGO® MINDSTORMS NXT brick to the bulldozer and managed to control the Power Function motors with the NXT and adding sensors to the bulldozer so it can be semi autonomous. [View previous blog].

I am really impressed by the attention to detail that has gone into the Bulldozer design. Today I came across this brand new video on the LEGO® Bulldozer web site that has just been posted there:

It is an excellent in depth look at the design process that happens when a new TECHNIC model (i.e. Bulldozer) is dreamt up. Click here to view it.

The following still from the video shows various alternate designs of the bulldozer that never made it.

This must be a dream job! What will you design if you have 6,500 different LEGO elements to chose from?

Edit (following DAG's comments):

Sketch models:

Thank you David, for your comments. I have tried to capture the closeup of nearly all of the sketch model the LEGO designer created from the movie. I hope this is what you were after:

(a) Bulldozer 1:

(b) Bulldozer 2:

(b) Bulldozer 3:

(c) Bulldozer 4:

(c) Bulldozer 5: pneumatic version - no motor

Here is a challenge for people who have the new TECHNIC Bulldozer. How many of the above models can you create without an instruction manual?

- Tim

Sep 17, 2007

RoboCUp Junior Australian Championships

September 1st and 2nd saw the RoboCup Junior Australian Open being held at the Gold Coast Convention and Exhibition Center.

There were approximately 150 teams across 6 divisions with roughly 350 students competing. We had teams from all over Australia, as well as invited teams from China and Singapore.

Damien Kee

Sep 16, 2007

FLL Mission Overview Part 2 - Solar Power Satellite

Objective: Press the red lever on your side of the table to unfold a solar panel on the satellite. Press the lever before the team on the other side of the table to make the radar dish point to your table.

Point Worth: 15 points for pressing your lever anytime, with a bonus of 5 points for pressing it first (making a total of 20 points).

Mission Location: North (top) center of field.

Estimated Difficulty Level: 1/10 for minimum points, may vary for maximum points.

Time Length Rating: Low

Unique Challenge Aspects: Only mission which incorporates a competition between the two teams opposite each other on the tables.

This mission is probably my favorite one this year. I always like the competition missions, because they're so easy to complete by themselves (or at least the past couple ones that I've been in were), but the competition aspect increases the difficulty level by an unknown quantity. You might have to hit the lever in 5 seconds to win in some cases, while in other rounds your opponent team may not even go for it! This adds a neat twist to the challenge, since you can never be sure that what you have is good enough. We'll probably be seeing some amazing solutions to this challenge at different state tournaments and especially at the World Festival.

Another interesting aspect of this challenge that is different from past years is the fact that it's located almost directly in front of the base! (hence the 1/10 difficulty rating) It almost seems like the designer purposefully made it like that to encourage teams to try for it. The fact that you get points for hitting your lever any time also encourages people to try for it, so there will probably be more teams going for it this year.


Richard's comments: Just a quick reminder that you are NOT allowed to switch the pointer to your side if you did not trigger it first. Some teams did things like this in past years, for example in No Limits, they scooped the ball out of the center hoop (the objective was to be the first to place their ball in the center hoop) and replaced it with their own. This called for some of the most amazing devices, but it looks like designers wanted teams to go another apporach this year.

Sep 15, 2007

The Green Monster, Team Hassenplug

Steve Hassenplug has done some amazing work over the years, and one of his newer models is no exception. I first saw this in person at NI Week '07, and was impressed with both the abilities of the big green wheels, as well as the novel turning and steering system. In The Green Monster, the front wheels are independently driven to allow differential steering. But in addition, the rear wheels are articulated to the front body, but also driven by the third NXT motor, leading to more power, and a wonderfully fun skidding way of going around tight turns.

Much more impressive than the look or power of this beast (it handles dirt, grass, and other surfaces with ease... I'm waiting for the snow fan-tailing videos), is the fact that Steve has used it as a testbed for coupling GPS navigation with the NXT. Take a look at the videos (from 14 Sep) on Steve's webpage for some impressive (not to mention rather humorous) navigation attempts (PS, Steve's back yard is considerably steeper than it looks in the video). Currently Steve is using RobotC to drive the robot, which is completely autonomous, simply following a set of waypoint coordinates. He's also used pbLua to communicate with the GPS, and there are even some people who have managed this with the stadard firmware (although it's rather unclear right now exactly how that is done).

Now, anybody know where I can get a really small, simple, BT-equiped GPS unit? Serenity needs a captain... :-).

Brian Davis

Sep 14, 2007

Idea Book is out!

The Idea Book is out - if you've pre-ordered a copy, you should see it arriving soon. We've got a special section in our forum where you can discuss the book, ask questions, and more.

If you find any errors, please let us know so we can include it in the Errata section and make a fix available for everyone who owns the book. (Yes, errors do occur in books, but the Internet has made it so easy to find and share corrections.)

And if you own a copy of the book and attend any future LEGO events (BW, FLL, BB, etc), bring it - if any of the authors are present, they'll be happy to sign it for you.

Sep 13, 2007

LDD file support now in NXTLOG

You can read the news here, but the following (edited) information may be useful to some of you who post regularly to NXTLOG.


"LDD files are now avail on NXTLOG - you can upload an .lxf file only and not the .bmp file... You cannot include an .lxf file as your main image as we wish to promote main pictures of robots... a "How to add an LDD file" info page to NXTLOG [is expected] in the next day or so."

More Info on the Bionic Helmet

Sorry for the delay, folks... here's more details on the Bionic Helmet. The Helmet fits on one's head (or rather, my head - it probably wouldn't fit on anyone else's!), and provides lights and SONAR. The Light Sensor provides the headlights (they actually aren't used for telling you when you're looking at the sun :-), and you can switch them on or off by pressing the Enter button. The US Sensors provide the SONAR capabilities. When you move close to an object on your left, a low-pitch sound will turn on, while an object directly in front of you would cause the NXT to make a medium-pitch sound, and an object on your right, a high-pitch sound. It works quite well actually, in terms of avoiding objects near your head - all objects lower than that become the shins' job of detecting (that's what shins are for, anyway - detecting furniture in the dark!).

You're probably wondering what good the SONAR capabilities would be when you can simply flip the headlights on. Well, one reason is to let you move around in the dark [ominous music]without being seen.[/ominous music] Of course, that brings up the obvious problem of being heard, but it's fun to pretend anyway. :P

The other reason for having the SONAR was the main cause of my building the helmet. Ever since I saw the US sensors, I've thought they could be used for helping blind people navigate on their own, by using the US sensors as guides. So with the helmet, a blind person would (theoretically at least - I guarantee you it wouldn't work in reality :P) be able to know if there was an object in his way, and which direction he would need to turn to avoid the object.

Here are some pictures of me wearing the helmet - front, side, and back views:

There are a couple things you can notice from the pictures. (1), the front view shows how I positioned the US and Light sensors to fit around the field of view - this adds a neat sort of look to the robot without inhibiting (too much!) the view. And (2), the back view shows how the tires are used to provide a cushioned strap in the back. I actually didn't have this at first, but after I put the NXT Brick on the front of the helmet (you really find how heavy that thing weighs once you try wearing it on your head!), the technic beams pushed too hard on the back of my skull for comfort, so I added the tires. Now I wish I had used tires for all the contact points of the helmet, because they help A LOT in making LEGOs more wearable and comfortable.


Serenity, a robotic LEGO boat

I actually started wondering about LEGO robotic boats a while back, when some threads on the NXTasy forums brought them up (as well as submarines). There were two main problems I could see for a "pure LEGO" water-craft: (1) Flotation (which could perhaps be solved by LEGO boat hulls, which re-entered the LEGO scene in a number of recent City sets, such as the Fireboat (#7906), City Harbor (#7994), and the Speedboat (#7244)), and (2) Propulsion. I did not want to deal with the risk of rotating seals for propeller shafts etc., so I figured on having all the electronics (including motors) above the waterline, with the propeller drive shafts either entering the water at an angle, or being driven by pure mechanical linkages to a completely submerged prop. But upon getting two of the Fireboat sets for the hulls, I decided to try using the stock LEGO underwater motors that come with these sets.

The result was Serenity (posted on NXTlog), a pure-LEGO robotic (not remote controlled!) boat.

Two hulls are tied together with bow and stern beams, made from studded beams locked together with studless elements, resulting in beams that can not pull apart under tension or flexing (the connection to the boat hulls is unfortunately studs-only). The NXT and two NXT motors sit along the midline, not powering the vehicle but in this case only steering the stock underwater motors attached below. To make the vehicle float level in the water, the NXT is on two long axles and can be slide fore and aft to trim the vessel (no port-starboard trim was needed in this case). Mounting the underwater motors firmly to a mounting frame was one problem, but was solved with some half-stud offsets.

The program uses a Hitechnic compass, trimming the rear motor like a rudder to keep the nose pointed along the initial heading. After a specified time (configured at the start of the program), Serenity makes a 180° turn "in place" by steering both the bow and stern motors, and then again tries to maintain a new heading opposite the initial heading, returning to the shore.

The scary part was testing this. I tested first in a small tub of water on my back deck, but then it was time for a more realistic "sea trial", and lacking a swimming pool my only option was a small local pond, with weeds, swampy shores, and an active fountain in the center. I didn't want to use a tether, as that would really be unfair (not to mention the drag of the tether would likely cause problems with the autonomous navigation routine), so the first "live" test (yes, as seen in the video) was more than a bit nerve wracking - if it didn't turn around, I'd just have to hope it would hold it's heading long enough to get to the far side before wandering under the fountain. And if there was any more serious programming or mechanical issue, there was a good chance I'd get to watch a LEGO-version of the Titanic disaster. Hitting the button and letting go was... tense. But careful pre-testing held - it worked almost flawlessly, through four trials until the underwater motors completely fouled on weeds near the end of the last trial (thankfully, close enough to drift in towards the shore). Even when bumped off course, the NXT faithfully corrected the heading, and it always executed a beautiful 180° turnaround at the midpoint.

Not too bad for a proof on concept (I'd not known of JP's amazing craft at the time, nor thought to use the dirigibles like that... not that I had any handy). It clearly needs a more reliable (non-fouling) propulsion (sidewheels splash a lot, I've tried, but I've got other ideas), and for larger lakes and rivers it probably needs to be bigger (if you are smaller than the local waves, there's going to be problems). But I'm curious how far I can take this... that is, how far I can take this project before turning it into an unplanned submarine.

Brian Davis

Sep 12, 2007

Vernier Sensor Adapter for NXT

Vernier Sensors will make their adapter for the NXT avaiable in October. You can find this adapter from LEGO Education.

With this adapter, any of Vernier's 40+ analog (BTA) sensors can be incorporated with the NXT. Vernier sensors can be purchased at

Update: Use the following link to view more details of the adapter: (If the above link causes trouble, the item number of adapter is W991377 on the United States site.)

FLL Mission Overview Part 1/14 - Roof Solar Panel

Following this post will be 13 more posts, in which Jonathan and I will discuss each of the FLL missions for this year. If you have not done so, you should read the Official Website ( first.

Objective: Place the Solar Panel onto the roof of the house by the sea.

Point Worth: 15 points

Mission Location: Northwest (Upperright) corner of the mat

Speculated Difficult Level: 7/10

Time Length Rating: Medium

This mission requires the robot to place a small Solar Panel onto the roof of the house in the northwest corner of the mat. We think that it will take a medium amount of time to complete the mission because of the accuracy required, but the location being somewhat close to Base, it will not take as long. We have also rated the difficulty 7/10 for the precision and the somewhat odd angle the house is placed at.

Good luck, and watch out for future posts,

Jonathan's Comments: One of the unique aspects I've noticed about this challenge is the type of "delivery" that has to be made in it. There have, of course, been missions in past challenges that require the robot to deliver something to a model. But if I remember correctly, most of them allowed for a reasonable amount of inaccuracy (for example, the ATP molecules in last year's NanoQuest theme just had to be dropped into a black frame). In this challenge however, the sonar panel has to be set at the right angle, has to be set down gently, and can easily be knocked off during delivery if the robot doesn't perform well. We'll probably be seeing some very interesting and well-designed solutions to this challenge.

Sep 11, 2007

Sept 11

We will never forget.

New Blog

RHPGuy has started a blog and is offering photos and downloads, including program files, videos, projects, and building instructions. You can check it out here.

(If you've got a website or blog dedicated to NXT, please post a comment under this post and the URL for us to check it out.)

Using the new Power Function motors with LEGO® MINDSTORMS NXT

In the last few weeks we have seen LEGO® introducing new kits with the Power Function elements. Right now the PF elements ship with the LEGO® Creator Dinosaur, LEGO® creator Ferris Wheel and of course the incredible LEGO® TECHNIC Bulldozer 8275 that has just hit the market a few weeks ago. The Bulldozer comes with four PF motors in total, two receivers, and one transmitter.

I been playing with the new PF motors. They are absolutely fantastic - it is easy to attach to the beams, and have incredible torque. They are smaller than the NXT motors (see the LDRAW sketch of it below in last week's post from Matthias) - in fact it comes in two sizes - the smaller one with slightly less power and the XL version with more grunt.

Currently you need the Infrared remote to control the motors. However, soon you would be able to control the motors directly from the NXT using third party IR bridge sensors when they become available.

The motor comes with its own power pack (with space for 6 AA batteries) which also powers the IR receiver. The IR remote transmitter takes three AAA batteries. I managed to get nearly 3 hours of playing from a full charge - so it is pretty impressive.

Here is a video of a NXT robot powered by the new PF elements. You can find out more about the project on NXTLOG.

Sep 10, 2007

More Details of JP Brown's "Rowbot" NXT

JP graciously shared with us more details of his amphibious NXT. (Photos are copyrighted by JP Brown).

What follows is a portion of JP's email to me regarding his robot. If you have more questions and comments about the robot, please post them here.

JP is willing to share a copy of his .NET program which drives the robot. If there is interest, we'll post the program on the blog.

"The blades enter the water just after the stroke begins and lift out of the water just before the stroke ends.

The main problem was writing the PC end of the Bluetooth link for control. I ended up with a fairly decent .NET control program which can take input from either a joystick or from the keyboard and mouse and then push commands to the NXT.

We tested Rowbot fairly extensively in the bath before we went on open water. As you will see from the photos, the fact that the oars can be disassembled makes transport easier:

The Youtube video shows the maneuverability (of the robot). After about 20 minutes of driving it around the pond we started to get horrible clicking noises and the speed went down to about a quarter. We directed it back to the bank and found that one of the two 8-t gears that drive the robot back-and-forth had come loose, so we decided to call it a day. I've rebuilt that part now, and hope to have another go on Sunday".

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