Robotics Competition: playing field

I have decided to hold an online robotics competition over the next few months. I don't have all the rules worked out yet, but I do have a playing field for you to play around with. It's a fairly simple playing field. It has 3 major field element arrayed in a line about a foot (30 cm) apart. Some of the playing field elements are not Lego, but Lego substitutes are allowed.

Playing field overview

In the center of the field is an obstacle. This obstacle should be a large book or a Lego plateau of similar shape. It should be about 1.25 inches (3 cm) tall and at least 8 inches (20 cm) long in the direction of the playing field's "line". The width from side to side doesn't matter much because there will be penalties for going around the obstacle. As long as it is wide enough for your robot to easily cross over there should be no problem.

Obstacle examples

Plateaus are difficult to construct out of Lego, but here's an inside view of how I made mine. The smaller baseplate is supported by several small Lego towers and held down at the corners.

Lego obstacle inside view

On one side of the obstacle is a triangular stack 15 of Lego cubes. These cubes must be made of Lego pieces, and they must have the exact dimensions 4 studs long by 4 studs wide by 3 bricks tall (approximately 4 studs cubed). The cubes are the scoring elements, so the object of the game is to put them into the goal.

A cube

A stack of 15 cubes

The goal is composed of an empty Kleenex box with the plastic removed or a Lego box of similar dimensions. If necessary, you could make a simulated Kleenex box out of cardboard. Kleenex boxes are approximately 4.5 inches (11.5 cm) wide by 8.75 inches (22 cm) long 3.5 inches (9 cm) tall with a hole 2 inches (5 cm) wide by 7 inches (18 cm) long in the center of the top. My Lego version is 30 studs by 16 studs by 9.33 bricks with a 6 stud by 22 stud hole. Note that my Lego version has no bottom. It shouldn't get flipped over during play so no bottom is necessary.


Now that you know what the playing field looks like, feel free to make one of your own and start testing prototypes. The full rules for the competition should be out sometime in January. I'm leaving for a week starting at 6 am on New Years Day (ughhhhh), so I won't be working on this for a while.


Pump-Action Lego Rifle

Here's the main video for my pump action Lego rifle. The video explains how the gun works and shows some better footage of it shooting stuff.

Pump-Action Lego Rifle


Sphere Eater

Since I make so many projects that scatter Zamor spheres across the floor, I decided to make a project that picks them up off the floor. I made a simple NXT chassis, then I built a holding tank on top of the NXT brick and an attachment to pick up the spheres. Since it seemed to eat the spheres, I decided to name it the Sphere Eater and I gave it a "Nom" sound effect that it plays whenever it detects a sphere being eaten. Since I already had the sound effect from "Nom Nom Nom Nom Nom Nom Nom", I decided to add some Nyan Cat music too. Fun.

Sphere Eater

To see some pictures and the program...


Hurricane Launcher mark VI

This is currently the newest model in my Hurricane Launcher series. Unlike previous models, this one doesn't focus on Rate of Fire (RoF) but rather on firepower density. The barrels are on two layers, staggered like the barrels of Brian Davis's Hailstorm Launcher to apply the force of the bullets to a smaller area. This weapon was used on Flash Flood, allowing it to destroy enemies at long range.

Hurricane Launcher mark VI


Cheetank: FAST Lego Tank

Today I was playing around with my Lego's (like I do every day), and I came up with an idea. Why not make a tank and gear it as fast as I can? I made a tank that's just a simple chassis, and I geared it 3:1 for speed so it flies across the ground. I named it Cheetank because it is fast like a Cheetah. When I tested it on obstacles, I was surprised to find that this tank performs almost as well as my greatest obstacle climbing tanks even though it has little torque. The sheer momentum of Cheetank bearing down on an obstacle enables it to drive right over it without stalling. The speed of the treads also helps it to achieve plenty acceleration even on rough or slippery terrains.

Cheetank: FAST Lego Tank


Backlog: Hurricane Launcher mark V

Because Maelstrom's gun, the Hurricane Launcher mark IV, was based off the mark II and III versions it didn't perform much better than earlier versions. I made little progress in Zamor launching technology until I created the Droideka pistols (post coming soon). Because each of them only had a single motor, they didn't fire very fast, but they used a new type of structure that was lighter than my previous Zamor launchers and I used that type of structure to produce the Hurricane Launcher mark V. It surpassed the previous RoF (Rate of Fire) record by 3 rounds per second, but more importantly it had a lighter structure and used less parts. My previous Hurricane Launchers used nearly a whole NXT set worth of parts each, but the mark V uses only a few large beams, making it easier to incorporate it into other projects by freeing up parts for use elsewhere. I have yet to make a tank using the Hurricane Launcher mark V as its gun, but I probably will at some point because the mark V is better than the previous versions.

Hurricane Launcher mark V

Pump-Action Lego Rifle sneak peek

If I told you all about it, it wouldn't be a sneak peek, would it? =)

Pump-Action Lego Rifle sneak peek

I'll tell you this much: It's a pump-action Lego rifle. But you probably already guessed that from the title.

Backlog: Maelstrom (Part 2: NXTlog and Instructions)

I posted 4 different projects on NXTlog for Maelstrom because of all the stuff I wanted to add. The following is 3 of the 4 posts, the other one is basically a repost of the Maelstrom YouTube video.

Maelstrom: The Ultimate Lego Tank

Maelstrom is my ultimate project: A giant Lego tank armed with a Hurricane launcher. It has a powerful drivetrain with suspension to let it climb over some really tough terrain and its Hurricane launcher can fire 23 Zamor spheres per second! That's 1380 spheres per minute. It has a 40 sphere magazine so it can only fire for 1.7 seconds straight, but with short bursts its ammo could last a while.


Maelstrom can be split into two main parts, the drivetrain and the Hurricane launcher. The drivetrain was developed over a period of about 1 month specifically for Maelstrom. It has a type of suspension I originally tried on Tempest (a Tornado Launcher tank) with mixed success. The suspension allows gravity to bend the tank's structure without breaking it so the tank conforms to the terrain. It also has sprung treads so they don't fall off when the tank bends. It is powered by PF XL motors geared for power and it has rubber treads at the front to aid in climbing.

Hurricane Launcher mark IV

Maelstrom is armed with the Hurricane Launcher mark IV, the fourth in a line of multi-motor Zamor launchers. Like the Hurricane mark II it uses 3 motors and like the mark III it uses an efficient firing mechanism. As I mentioned above, it is capable of firing 23 spheres per second, which is faster than many real machine guns. Needless to say this thing can devastate Lego structures (stacked Lego bricks, not pushed down) and armies.

 Hurricane Launcher mark IV Instructions

This project is the instructions on how to build the Hurricane Launcher mark IV, the weapon of Maelstrom. Here's an overview of how it works: The 3 motors spin 24 tooth gears which link to 8 tooth gears (which rotate 3 times as fast) on a long crankshaft. In 4 places along the crankshaft it is displaced from the center to make that section spin around the crankshaft's center. Attached to those sections of the crankshaft are 4 firing mechanisms that push/pull the firing rods in and out of the Zamor launchers as the crankshaft spins.

 Maelstrom Drivetrain Instructions

This project is the instructions on how to build the drivetrain of Maelstrom. Here's an overview of how the suspension works: Along a few points in each side of the drivetrain there are joints that allow it to bend. Each joint connects 2 main beams with other beams and only a few pegs. To keep the joint from falling apart an axle runs through it. Also, to keep the treads from falling off they are sprung by arms pulled up by rubber bands.

If you have any questions about the instructions, feel free to comment on this post. I'd be happy to explain.


Semi-Automatic Lego Pistol

I recently got an email from my friend whom I met on YouTube as jintzd. We've talked before about ideas for Lego projects (especially guns and tanks), so this wasn't the first time. In any case, this email was about HOZL, short for Hand Operated Zamor Launcher. He said it was a semi-auto Zamor launcher pistol. I liked the idea so much, I decided to make my own version, generically named "Semi-Automatic Lego Pistol" because I didn't bother to think up a good name. Despite the terrible name, this gun is pretty awesome. It can easily be put in a pocket and pulled out when needed, plus it can fire quickly, so it makes a great pistol.

Semi-Automatic Lego Pistol

ToothBot Revisited

As I mentioned in the ToothBot post, the program was pretty bad. For that reason, I decided to rebuild ToothBot and improve the program. The hardware is the same, so I won't explain that again. Here's a demonstration of the new program in action:

ToothBot Revisited

Backlog: Maelstrom (Part 1: History and Videos)

Maelstrom was my Ultimate Lego Tank, and to this day it is unmatched in firepower. Maelstrom was, in many ways, an improved version of Tempest. The idea for Maelstrom was that I would get some Power Functions (PF) motors to use in the drivetrain so I could build a full Hurricane Launcher for the weapon. Soon after I got my PF motors, I began work on the drivetrain. It was fitted with the same suspension as Tempest, but it was necessarily larger because I wanted to fit a huge Hurricane Launcher on it. The original drivetrain was great at climbing over all sorts of terrain, and it was fast too.

Maelstrom drivetrain prototype

Soon after the first prototype, I added some rubber treads to the front to improve its climbing ability. This allowed it to conquer some really tough terrain. Unfortunately, Maelstrom was too heavy to climb over most of the terrain the prototype could.

Improved Maelstrom Prototype

At this point, progress came to a standstill for a while. I had used most of my beams on Maelstrom's drivetrain, so I didn't have enough parts left to make a Hurricane Launcher. I ordered a pack of parts from Lego Education, but it was nearly a month before I could resume work. In the meantime, I made a video explaining Maelstrom's suspension.
Maelstrom Suspension Explained

At long last, I constructed the Hurricane mark IV and put some finishing touches on Maelstrom. This project had taken nearly a month of my summer, more time than I even spent on another Lego project.
Maelstrom: The Ultimate Lego Tank

It's also worth mentioning that this was the first appearance of DroidFreak BattleTech and its logo.

Before I took Maelstrom apart and as I took it apart, I took enough pictures for an NXTlog project and for full instructions. I plan to post those here, but this post has already gone long enough, so I'll post those separately soon.


Panthera: A Climbing Lego Tank

Panthera is the name I have given to my new terrain-climbing tank. You may have already seen it in the Flash Flood video. Here's the full video of Panthera:

Panthera: A Climbing Lego Tank

Panthera came about because of a flash of inspiration I had while bored at school. I had been experimenting with a combination drive and suspension consisting of several small treads that can pivot around a point. Suddenly, I though of a way to put such treads on a tank. If I placed them at the front and back of the tank's treads, they would aid greatly in climbing. I drew up a detailed blueprint of this tank, as well as a frame-by-frame sequence showing it climb over stuff. This is a picture of my drawings:

The picture quality is quite good, so feel free to zoom in and read my notes.

When I got home, I hastily made a video of Flash Flood, which was my current tank, and then I built a prototype of Panthera. Soon after that, I tested Panthera on stairs and added some clips of it to Flash Flood's video. At that point I hadn't named it, though I was thinking of naming it after some big cat because of its four paw-like rubber treads. When I discovered that all four of the commonly known big cats (Lions, Tigers, Jaguars and Leopards) belong to genus Panthera, I decided that should be the name of this tank.


Backlog: Lego Shotgun Catapult

Sorry I haven't posted in a while. I've been busy with school stuff, and I was sick for about a week. Now that I'm done with school for the holidays I'll be posting a lot.

This is a "lost project" because it hasn't been posted anywhere until now. Unlike most of my projects, this one uses no electronics. It's a catapult I made a while back that fires 50 small projectiles (axle pegs) over a wide area. Here's the YouTube video I just posted:

The YouTube video explains what it does, so I'll launch right into an explanation of how it does what it does.
This catapult gets its power from rubber bands, but unlike most catapults the power is transferred through gears. The rubber bands pull back on one lever arm which is connected to a 24 tooth gear. The 24t gear meshes with a 40t gear attached to the main arm. This setup helps to maximize the power of the rubber bands.
Because the small arm has rubber wheels protruding from it, it contacts and stops the main arm just as it reaches a 45 degree angle. This maximizes the range by releasing the projectiles at the best possible time.
The 50 projectiles are held within the holes of 5 parallel beams running up the main arm. Because the axle side of the axle peg projectiles is in the hole they smoothly release most of the time, but sometimes they stick and don't fire or fall short. If this were to be used as a practical weapon, there would have to be a way to keep projectiles from exploding unless they fell far enough away from the catapult.


Flash Flood: Sniping lego tank

This is a new Lego tank I made just a little while ago (thus no "Backlog"). It's a bit like Maelstrom in that it's a big tank armed with a Hurricane Launcher, but it's also quite different. It has independent suspension and it features the new Hurricane Launcher mark VI that uses a staggered arrangement like the Hailstorm Launcher to concentrate it's damage into a smaller area. The YouTube video also includes a few clips of my next tank (the one I'm working on now), which isn't very practical but is really cool. It's a nice proof of concept.

Flash Flood

Backlog: XPS

XPS, or the eXperimental Propulsion System, is a small robot chassis made mostly from pieces in the NXT set. It was originally posted on NXTlog over 2 years ago:

XPS (experimental propulsion system)

XPS is a chassis I invented to climb over things. It's based off of a pair of treads and includes 4 wheels as well. It uses all 3 NXT motors. 2 motors power the treads and the other powers the forward pair of wheels to assist in climbing. The rear pair of wheels is unpowered as it is strictly for support. If you want to see XPS in action skip to the video at the bottom.

 Tread Base

This base is what moves the bot around during normal driving and does most of the work in climbing. Picture 1 shows the tread base Pictures 2-5 show close ups of half of the tread base. If you want to duplicate this project, carefully construct one half of the base and then make the other exactly opposite of it. The next section tells how to connect the two halves.

Tread Base and NXT construction

Picture 1 shows the connection assembly for the drive base. Picture 2 shows it disassembled (so you can see the pegs). Picture 3 shows the connection assemblies for the NXT in their proper position. Picture 4 shows on of the NXT connection assemblies by itself.

Front Wheel Assembly construction

Pictures 1 and 2 show the two steps to making the half attached to the NXT. Pictures 3 through 5 are steps to making the motor half. Once you have made these two, it should be simple to connect them.

Movie and Program


I would be happy to see someone continue on this project by putting stuff on the chassis. They would have to use pf motors of course, but I don't thing it'd be that hard. I recommend that they add weight near the front and as low as possible, because the robot has a tendency to topple on sharp inclines. It may be necessary to build things on top of the NXT brick, just make sure you build around the buttons and screen and it should work. If you continue on XPS, please post a comment so I will know to check out your project!


Rubik's Cube Solution PDF Files

I uploaded some PDF files of my Rubik's cube solution for your convenience. The first, which you can find here, is the complete cube solution copied from my blog posts (7 pages). The second, here, is just a list of all of the algorithms (3 pages). Once you've solved the cube a few times, you should be able to switch to the shorter algorithm sheet so you don't have to carry around and search through the full 7 pages to find algorithms. Happy cubing!


Backlog: Tempest (a "lost" project)

This is one of my "lost" projects, because I made it a while ago but never posted it anywhere online. But I'm getting ahead of myself. Let's start from the beginning:

When I discovered Brian Davis's projects, not only did I find his Zamor launchers, but also his Zamor launching tank. Ogre, his tank, is armed with a Hurricane launcher and has sprung plastic treads. Needless to say, that thing is awesome.


After I invented the Tornado Launcher, I finally had a good one-motor weapon to put on my own Lego tank. Because this was during the Robotics season where I was building BogieBot, I wasn't content to give my tank a simple tread base. I wanted to give it awesome suspension. Naturally, my first design used rocker bogie suspension. That turned out terribly, because my tread base was too small and my center of gravity too high. That is, it tipped over really easily. Here's a picture of my original design without its treads:

Original design:

After that design failed, I had a stroke of inspiration. Suspension should allow the treads to bend around the terrain without breaking the frame, so why not just make a bendable frame? You may know this suspension style from Maelstrom, but this came first, and this was where I invented it. Tempest turned out awesome, and although I didn't show the Tornado Launcher firing in the movie Tempest had it and could use it.

Tempest movie:
It's kind of incredible (as in unbelievable) that I left this thing unposted, because it was awesome, but I think I know why. Shortly after I built this, my robotics team realized that BogieBot needed to be revamped, and I spent nearly all my time for a few weeks on rebuilding or reprogramming it. During that time I posted 4 YouTube videos of BogieBot. No wonder Tempest got lost in the rush!


Backlog: Tornado Launcher

A few weeks after I made the Hurricane Launcher mark III, I had a new idea for a super-efficient Zamor launcher, and it produced the Tornado Launcher. It only uses one motor like Brian Davis' guns, but thanks to my awesome firing mechanism it fires faster than even the Hailstorm Launcher with only 2 Zamor launchers. It fires 13 spheres per second, blowing away the 9.5 spheres per second of the Hailstorm Launcher.

Tornado launcher

I also posted the Tornado Launcher on NXTlog under the title Compact High Speed Zamor Sphere Launcher. It included a short video and full instructions. The tank I mention in the project never worked quite right, but Tempest (Spoiler: I'll post a video of Tempest soon), another Tornado Launcher tank actually worked quite well. Here's the instructions: