DominoBot NXT (ver1)

May 2006:

Update: DominoBotNXT has been enhanced. See DominoBot2.

For those who do not know about the Lego Mindstorms Developer Program (MDP), back in January of 2006 Lego was seeking assistance from the Lego community on their next generation Mindstorms product (NXT). Approx 9600 people applied to become one of the 100 MDP’s. In late February, I received an invitation to participate and of course jump at the opportunity. For a few months, the group of us were under an NDA (Non-Disclosure Agreement) where we could not talk, show or discuss anything about what we had been working on in the MPD. Now that May 1 has passed, we can now open to discuss some of what we have been up to.

We all had an opportunity to participate in different areas of the testing/development process areas from software to Bluetooth to building robots. Initially, I wanted to get involved in more than one area, but time was limited, so I decided to focus on building only. I wanted to try and re-build my original DominoBot robot to see if I could make a better, more efficient version of it. I also wanted to test the new motors’ built-in rotation sensors – as I needed this functionality.



Climber – One day while browsing the LEGO Mindstorms site, I noticed some pictures about a show in Germany. LEGO had built 2 cool wall climbing robots to help market the product. I was amazed at the design and capabilities that they had and wanted to find out just how hard it would be to build something like this and have it actually work. It was quite a challenge. Building the components was the easy part. Getting it to climb was (and still is) a challenge. The Climber has gone through another iteration as the one shown here is too heavy. To test the unit, I used a holesaw to cut 2 inch offset holes up a piece of wood plank. The idea would be that the Climber would start with one arm, pull itself up, and the the bottom part would shift. This would offset the Climber to one site and make it easier for the other arm to find a hole and pull itself up. This was to be a big challenge. Read on…

Showing the back of Climber. Features – the cam mechanism that turns the head can be seen at the top. One of the problems that I discovered after building it was that its design was correct in that it had the geometry to climb my test wall. The problem is that it is too heavy for itself. I should have called it Big Mama, cause it ain’t going nowhere but the bottom rung…


DominoBot 2

DominoBot 2 was my take on re-creating my original DominoBot. After I had finished the original,
I found ways to make it more efficient and better at what the original did. I also did not have the limitations of the parts supplied with the RIS and UBS sets.
One of the parts that needed re-designing was the mechanism used to force domino’s out of the chamber. The original tended to have difficulties at times. I devised a mechanism using rack plates (3 – 1×4′s). It is driven by the same motor that moves the loader arm, but the method does not allow slip-up or misalignment. A touch sensor at the full-out and -in positions ensure that Dbot2 knows exactly when a domino has been pushed out and when the rack has reset.

Check out newer versions of DominoBot (NXT).



Rope Climber has been built for the rtlToronto Lego Robotics Event – Rope Climbing.  In a nutshell – build a robot that can find and climb a rope.  Sounds easy right?  Not!  In the tradition of rtlToronto, there are some interesting rules to make this more challenging.  First off – the robot must fit within a 8x8x8 square on start.  The trick – the rope is hanging 12 inches off the ground.  The robot must “grow” to catch the rope.  The robot must also start 36 inches from the rope.  This requires it to be able to drive and find the rope.  The 8 inch requirement also is important to consider once the robot reaches the top.  In order to win, the robot must be above a marker placed on the rope.  This marker will be 12 inches from the top.  This robot extends to 14 inches, so it must also “contract” when it detects it is at the top.


PicoCam was built as a proof of concept.  Its purpose was simple, navigate an area using typical avoidance routines while capturing live wireless video/audio and transmitting it to a receiver. The was never really completed because I had other ideas brewing…  The pictures shown here are of the final version, with working navigation, but I did not bother going the last step to get the live video to display (even though it will work).


You would think I have a template for “room-navigating” robots… TrackerBot evolved from the recent PicoCam robot I created.  After I had finished PicoCam, I decided I wanted to try something with tracks.  TrackerBot and PicoCam share similar intelligence, with TrackerBot having some slight improvements.  The general idea is that it will navigate a room using a variety of sensory input for obstacle avoidance.  There are 3 Cybermaster touch sensors, 1 DIRP light sensor and 1 line following standard Lego light sensor.

The DIRP light sensor (seen here at the top), does most of the work.  It is set-up as a light sensor and detects left, center and right objects. It does a pretty good job of making sure TrackerBot does not hit things.  The Cybermaster touch sensors are used to detect objects that are low, at the back or out of the line of sight of the DIRPD sensor. They are wired such that all 3 sensors can be placed on one port (more on this after).

TrackerBot is also equipped with a pinhole wireless colour camera.  It can broadcast live colour video with sound to the receiver and show its progress on TV.  It is more of a proof of concept than any real function.  Read on for more details…



Big Wheel (BW) was an experiment at building a robot that uses the HailFire Driod (StarWars) large wheels. It’s job is simple; build an autonomous robot that can navigate any area while avoiding obstacles by not hitting them in the first place. To do this, BW uses a DIRPD sensor to “see” left, right and center. This allows BW avoide obstacles from 3 views before actually hitting them.



One of my early projects was to build a fire extinguishing robot. I did this using the parts I had at the time. It was based on a walker platform and used a pneumatic circut to “blow” the fire out when detected. It worked reasonably well with the provided light sensor. Recently, I discovered the PIR (Passive Infrared Sensor) from TechnoStuff. This sensor was built to detect infrared heat and seemed to be a good fit for my next project. I mounted it to my new FireBot in tandem with a standard light sensor. Together, they would do the job of detecting a flame.

A candle was used as the “fire” in this project. The PIR sensor was mounted alongside with the standard Lego Light Sensor. For more details on this sensor, visit my Reviews section.

Johnny 5

Johnny5 was built more as a test to see how similar I could build him out of lego.  Programming on Johnny5 was simply line following with object avoidance via touch sensors at the front. His hands and head would also move in a pre-defined pattern.  The pneumatics are there for visual effects.  They serve no function on this model.

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