April 2007:
What better way to test a colour sensor then to create a brick sorting robot! After getting my hands on a HiTechnic colour sensor, I first took a stab at creating a robot that could navigate a room and detect colour. There was only one problem, it could not really do what I was hoping for. I was nieve in thinking that I could build this robot and it could detect colours from a distance. After reading the fine print on the provided documentation, I quickly realized that the colour sensor is only capable of reading colours at very close range (~ 1 cm). My bad. Of course, you could still build a robot that uses the ultrasonic or other sensor to get it close to objects, then read the colour… but that’s for another time.
BrickSorter uses this colour sensor to detect the colour of bricks and sort them into a variety of cups. The program is quite simple, gravity and studless beams allow for each brick to slide down the track on its own. when a brick is next, the colour sensor takes a reading (more on this later), the sort motor turns the sort rails to the correct cup, the sort rail motor changes its angle depending if the cup is close or far and finally the kicker motor kicks the brick in motion.
After a lot of fooling around with the cup placement (which seemed to be the hardest part of this project!), I managed to get the sorting pretty much bang on. Of course, the video shows some goofs, but that is mostly due to the small sized cups (its all I had!)… Anyway, I found the sensor to be accurate most of the time, but ambient light still influenced the readings at times and caused for the odd random missorting of a brick. I had to shoot the video about 10 times to get cup placement and sorting goofs worked out.
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April 2007:
Your first question is probably “what does UNV stand for?”. Well, its nothing special – I simply could not come up with a name for it, so what better way to tag it then simply unnamed vehicle. After receiving a bunch of the new tread links, I wanted to create something grand with them. Scouting the web, I came across these multi-purpose robots (see below) that can be outfitted for police / bomb squad use, or for scientific work. Thought they looked pretty cool, so they were the inspiration. UNV was sitting around for months before I finally got around to taking pictures and a video of it. Read on for details…
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Jan 2008:
WifiCamBot was one of my adventures in building a robot that could be remotely driven around while transmitting video via a live feed through an IP-based network camera wirelessly.
The idea came from my wanting to do something simple. Survey underneath my deck to see what sort of critters etc were making a home there. The deck was high enough for a rover-like vehicle to fit and drive around. I did not want to have wires tethered to the system, so I used a Panasonic BL-C30 WiFi camera with a built-in webservr to transmit live video via the web.
In this case, I have a webserver where I created a subdomain specifically for the camera to broadcast its info to. Loaded the Java components to receive the streaming video and render it on the site. The site also allows for remote control of the camera via WiFi. So, the entire robot, power and electronics are all onboard. There were a few challenges with this approach. 1) Power – The Wifi camera required 12 volts dedicated power. I did this by wiring 2 battery packs together in series (required a custom modified motor wire). This also added a fair bit of weight to the robot. In total there are 2 battery packs for the WifiCam and 1 for the PowerFunctions motors. That is 18 AA batteries. No worries though – the PF motors still have lots of torque.
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December 2006:
Sometimes my robot building ideas are spurred by nothing more than wanting to make use of one or more cool items that I get from time-to-time. In this case it’s two – tread tracks that can be had if you own the Technic Snowmobile (8272) and a TechnoStuff Tilt/Accel Sensor. 
I was fortunate to have received a huge bag (a few hundred segments along with wheels) of the new tread tracks a while back and begun playing with them to see how they compare to their smaller black Technic counterparts. In a nutshell, I like these ones better as they are larger (more suited to the size of robots and Technic creations I build) and stronger – they dont come apart as easy. They also have pin holes in them to boot, so the sky is the limit for making large tracked vehicles.
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Feb 2007:
CT1 was a quick build to test the HiTechnic Colour sensor that I recently received. Being the type that does not read the fine print that often, I had it in my mind that I would build 
a robot that could navigate around and rhyme off colours of objects that it “saw”. It was not until I tested it that objects have to be within 10mm distance to get any sort of decent reading as to its colour. So, intead I ended up with a fast agile little bot and decided to take some pics of the platform. At the least I found yet another way of building a micro drive platform for a small robot…
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The folks at Mindsensors were kind enough to send me over this 
Magnetic Compass sensor to test. The sensor serves the useful task of providing the NXT with an indication of its heading angle from magnetic North to the NXT. It uses orthogonal two-axis magnetic sensor from Honeywell (HMC1052) and provides digital communication with NXT. Click the image below to see a video showing the compass in action. I did a brief test of this sensor and it worked as expected. More on this later…
Construction:
The sensor uses a standard NXT cable plug to interface the unit with the NXT. It is not encased in any plastic or bricks. Instead, it provides standard width Lego mounting holes to integrate with studded or studless beams and connectors.
Have a sensor or add-on that you want reviewed? Drop me a line.
After building my original DominoBotNXT I was not happy with the need for it to backup each time a domnio was placed. (see link for details on this). The stanard NXT system provides only 3 motor ports. On DominoBotNXT, 2 were used for the drive wheels and 1 for the domino placement gate. This resulted in the need to tied the domino conveyor that carries each domino to the gate to be driven directly from the left drive wheel. When placing a domino, the distance between each was too wide, so it would have to back up each time one was placed. To fix this, I needed a 4th motor and a means to drive one. So, how do you do this with only 3 motor ports you ask??? Good question, I’m glad you asked as that is what this page is for….
The Motor Multiplexer from Mindsensors attaches to a single sensor port and allows the NXT to drive an additional 4 motors. In my case, I only needed 1. Using RobotC, I was abled to write (with some help from Dick Swan and Nitin Patil – thx guys) code that would allow communication with the IC2 interface on the sensor to control the 4th motor. So, in the programming environment, I simply had another motor port and use it in a similar way to the 3 core ports on the NXT. It only took a little bit of code to get this working. Now, DominoBotNXT can continue to drive forward while placing domino’s – making it much faster at its task. For info and a video on this, visit my DominoBotNXT2 page.
Results:
I am happy with the way this sensor works. I was working with a pre-production beta version that had some glitches (one port did not work), but I have been assured that the production units have this addressed.
Construction:
The sensor uses a standard NXT cable plug to interface the unit with the NXT. It is not encased in any plastic or bricks. Instead, it provides standard width Lego mounting holes to integrate with studded or studless beams and connectors.
Have a sensor or add-on that you want reviewed? Drop me a line. 
After I had success with my challenge to build a 1″x1″x1″ NanoBot, I wanted to try my luck at something a little larger. MicroBot measures approx 2″x2″x1.5″ and uses the same Atmel microcontroller and battery (see N 
anoBot details). The body was custom made from a larger piece of 4mm white PVC. MicroBot gets its’ senses from 3 front mounted ProxDots (IR units) and a bottom mounted IR unit (for line following). This gives MicroBot the ability to detect left, center and right objects and to react accordingly. The drive motors are self contained units pulled from some old LS120 laptop disk drives. The motors are used to eject the disk so they have a great amount of torque for their size.
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While waiting for the NXT system to come out, I decided to try my luck at making tiny robots. While Googling, I stumbled across a Yahoo newsgroup for NanoBots based on the MegaBitty controller. I have always been int
erested in making compact Lego robots, but for obvious reasons, they can only be so small. So, I decided to try my luck and NanoBots. Although I am not sure of the exact definition of a NanoBot, I believe it has specific maximum size limits for competition which is approx. 1 inch cubed (1×1x1). This is my first venture into non-Lego robots. NanoBot uses a variety of pico-sized components including:
- Atmel Mega 8 Microcontroller
- 2 GWS Micro Servos – hacked into the gearbox below.
- A 3.5V IPOD Shuffle battery unit w/built-in charger.
- CJH line and object sensing base and front circuit (uses SMT components)
- None other than Lego minfig wheels
Some of the key electronic components used on NanoBot are:
- AtMega8P main CPU (IC AVR MCU 8K 16MHZ COM 32-TQFP – ATMEGA8-16AC)
- Photointerrupter Line sensor (x2) 424-1096-5-ND
- All caps, resistors, LED’s are surface mount technology (SMT)
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My Old Site (2006-5 – 2009)
My Old Site (2005-2006.5)
The following is a snapshot of my old site…
