This week I explored the world of robotics, and the use of Arduino as the "brain" of the robot. 

Materials

• Boe-Bot Robot Shield for Arduino
• Arduino Uno
• Batteries
• Small screwdriver

Project Description
This project was a great introduction to the field of robotics and a good extension for my learning of the Arduino programming language. Parallax, the company that makes the Boe-Bot, provides a comprehensive tutorial that starts off with Arduino basics, then follows up with construction of the robot and programming the onboard Arduino to react to environmental factors such as light, distance and more. 

Results and Challenges
Assembling the robot was very straight-forward, and the tutorials prepare you well for getting all the wiring set up correctly for each mini project. The ultimate goal is to program the robot to navigate its environment independently. 

In the video below you will see how this robot is programmed to avoid structures it confronts along its path. It does this by using the two black "eyes", actually infrared (IR) LEDs, which shoot out infrared light that is then reflected by objects in front of them, and captured by IR receivers mounted directly behind the LEDs. When the IR receivers detect the infrared light coming back (meaning they are bouncing off an object), the robot backs up, turns a little, then goes forward again, thereby avoiding contact with the object.

There were some missteps in this process. I was getting a lot of false readings in the beginning, and it appears to be due to other florescent lights in the room, which can throw the sensors off. Another issue was where the IR LEDs pointed. If they were both straight ahead, it was hard for the robot to detect something at a slight angle. Small adjustments here and there seemed to do the trick.

Since shooting this video, I have uploaded new code that allows the Boe-bot to navigate a bit more smoothly, and to avoid objects ahead of time, before needing to back up. It's not perfect, and there's more I want to experiment with, so another blog entry on this topic may come in the future.

Today I wanted to learn a little more about Arduino. I picked up a PIR sensor awhile back because I thought it would be interesting to learn how to make the Arduino react to the outside environment. A PIR sensor can detect motion at different distances, and send a signal back to the Arduino. When there is no motion, it sends a zero, but if there is motion, it sends a "1".

This sounds really simplistic, and it actually is. A "0" and a "1" are all that are needed to make things happen. With the right code, the Arduino can tell a light to turn on, or tell a buzzer to sound, when a "1" is received on the board. It can do many other things as well, but this was a good starting point for me.

I didn't have the background knowledge to write the code from scratch, so I searched the web. At Makezine, a person had posted just such a project, PIR Sensor Arduino Alarm.

Using this tutorial, I gathered my parts, and assembled the project. Below are some pictures of the following materials:

1. Arduino and breadboard
   
2. PIR sensor
   
3. LED
4. Piezo buzzer
5. Connecting wires

Testing Out the Build
I assembled my materials according to the tutorial, and grabbed the code (sketch) from the website to upload to the Arduino IDE on my Mac. From there, I sent the code to the Arduino board and tested it out. Below is a short video clip of the results. As I move my hand in front of the PIR sensor, it reacts by sending a "1" to the board. Arduino then reacts by turning on the LED and sounding the buzzer.

Introduction
I built this week's project out of necessity. Since I have been using the soldering iron more lately, I needed a way to get rid of the fumes from the solder, which are not healthy to ingest. Although a well ventilated room is always a good solution, having a fan that can extract the fumes is even better. I was inspired by many similar projects on the Instructables website, and thus gathered the following materials:

1. A used fan from the inside of an old computer (12V);
2. A used 12V DC power adapter, found in our tech room;
3. A small toggle switch from Radio Shack;
4. A spare piece of carbon filter from a portable air purifier;
5. Cardboard, glue gun and tape.

Testing
After cutting off the plug from the 12V DC adapter, I connected its two wires to the two wires on the fan using electrical tape, temporarily. When ready, I plugged the adapter into the wall to see if it powered the fan. I had to switch wires around until it worked (In this type of project, there's no harm in mis-wiring because the fan will either turn in the opposite direction, or in my case, just not work).

Connecting the Switch
Once I got the fan to work, I took off the temporary electrical tape. I then re-connected the ground wires together with solder to make it more permanent. For the positive (red) wires, I took the toggle switch and put it in between, soldering one wire to each leg of the switch. This way, I can use the toggle switch to turn on and off the fan as needed, while leaving it plugged into the wall.

Adding the Filter
Once I got the switch to work, I then added the carbon filter. I cut a piece just big enough the cover the intake area of the fan, and used a glue gun to seal it on. It's important to remember that you want the fan to pull air IN from where the filter side is, so you should feel the draft of the fan on the back side.

Final Touches
Once all the main components were assembled, I cut out some cardboard to make a simple stand and a place to put the switch so that it wasn't just laying on the ground. I may follow up with a version 2.0, using wood or some other permanent material, but this works just fine for now.