This page is dedicated to the further enhancements that I have done to DominoBotNXT. For more info on the original DominoBotNXT, have a look here. 
One of the drawbacks of the original was that due to the 3 motor limit, it had to backup to properly place dominos. This was because the domino-placing component was tied directly to the drive wheels. So, as it drove forward, a domino would make its way to being placed in the holder mechanism. Doing this caused the robot to move forward approx. 4 inches. Since this is too far for domino’s to actually cause any chain reaction, the robot had to move each newly placed domino back to be within 1″ of the last placed one.
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ne of my early Mindstorms 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 sensor was set as a Light Sensor:
SetSensorType(SENSOR_2, SENSOR_TYPE_LIGHT);
The code was straight forward. When the sensor detects a value > 40, it “see’s” heat. In order to get accurate readings for this, it is recommended to take numerous readings (say once ever 20ms) and average them. This is to avoide variances in the sensor detecting other movement such as humans or other devices giving off infrared. As noted previously, the robot used both the PIR and a Light sensor together to detect the fire. By taking readings from both sensors and comparing their results to what would be expected when a flame is near, the robot was better able to detect the flame. To view the code, see the FireBot details page and download the source code.
Results:
The sensor worked well, but it is best to combine it with a light sensor. Together the two can be used to detect a fire or other object giving off infrared.
Construction:
The quality of the product both in workmanship and function is top notch. It is obvious that Peter takes time and know-how when creating each one of these. The visual quality of the sensor may make you think that this one came from Lego themselves if it wern’t for the TechnoStuff logo on the side…
TechnoStuff Home Page 
One of the my challenges was to build a bot that could effectively avoid obstacles before it hit them. My first attempt was to use the Lego Light sensor and the RCX to do this. The RCX would send out IR pulses and the Light Sensor would be used to read them and, based on how long they took to get back to the Light Sensor, could determine proximity. This worked realively well, with the exception that it was difficult to “tell” which side the robot should “look out” for… I came across a Dual Infra-Red Proximity Detector (DIRPD) that is currently being made and sold by Peter Sevcik.
Once I received the unit, I went fast to work. My plan was to build a robot in time for Christmas to deliver a set of diamond earnings to my fiance as well as test the abilities of this new sensor. The bot depicted is a paired down version of the actual one that was used, but it still functions in the same way.
The sensor was set as a Light Sensor SetSensorType(SENSOR_2, SENSOR_TYPE_LIGHT); The code was straight forward. The bot would drive forward until SENSOR_2 returned one of the following values:
0 Object in front.
22 Object on left
48 Object on right.
75 No object detected -continue
Based on those values, a decision would be made to turn in a specific direction. I also added in some randomizing for when the bot met an object head on.
Results:
The sensor worked exceptionally well. Reaction distance was predictable at approximately 16 to 24 inches. I only stumbled across one minor issue. The bot would have difficulties when approaching a standard doorway (i.e. bedroom) from the center. Both left and right would trigger and the bot would get stuck trying to decide what to do. This is easily fixed by building a routine that could detect this, make the assumption that it was a doorway, stop detecting, go through for x amount of time, and proceed with detection. This is also proof that the sensor is doing exactly what it was designed to to.
Construction:
The quality of the product both in workmanship and function is top notch. It is obvious that Peter takes time and know-how when creating each one of these. The visual quality of the sensor may make you think that this one came from Lego themselves if it wern’t for the TechnoStuff logo on the side…
Summary:
If you are looking for an effective, easy-to-use sensor for proximity detection, the DIRPD is it. It is easy to mount, program, fairly priced and looks good too boot! Good work Peter.
Have a sensor or add-on that you want reviewed? Drop me a line.
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…
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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).
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Wall Follower was one of those “proof-of-concepts” robots. The intent was to build something small and compact that was fast and versatile. Wall Follower can navigate around a room, on a table, in a maze, whatever. It is built from one of the basic robot platforms in the Mindstorms Contructopedia. Motion is done by 2 motors, each of which can steer by removing power to one. The main sensor is the DIRPD sensor (grey) mounted on the front. Through programming, the sensor can detect 3 distance ranges, near, far and too-close. The NQC program has a few main tasks. They are:
1) To follow the wall and avoid obstacles without hitting anything using the DIRPD sensor.
2) If it gets stuck, a routine will get it out of the situation
3) If it reaches an area where there is no wall and a drop-off is present. Detect an avoid.
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Spaz is my take on the famous LegWay robot first built by Steve Hassenplug. The version here is not quite the same as Steve’s, but more like the one built by Philo called “Yet Another LegWay”. The difference being, I did not have the special distance sensors that LegWay uses. Instead, Philo built a version that uses the regular Lego light sensors.
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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 8×8x8 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.
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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).
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