Arduino - Adventure #2

I've been spending a lot of time with AppInventor (more about that later), but I finally got back to the adventures (chapters) in my new Arduino book. Adventure #2 involves controlling a set of 3 LEDs with a potentiometer. This book is setup really well for students in that it takes you through the project in little steps. First, I connected 3 LEDs and lit them up in series (similar to chapter 1, but in triplicate). Then I hooked up the potentiometer by itself and played around with the different position settings. The final activity was to control the illumination of individual LEDs based on the position of the potentiometer. This book is great, because it not only teaches Arduino programming, but basic electronic circuitry. Chapter 2 also describes how to print status messages in the Serial Monitor on the computer screen - a really handy feature when you're trying to debug a program.

The final challenge in this adventure was to build a little electronic sign. This brings in the creative aspect for kids, and I would have constructed my own sign if I would have had a set of markers and some poster board handy. Next time.

Minecraft

I've been trying to teach myself how to play Minecraft. While it's not exactly a STEM-specific game, it seems to be all the rage among kids, so I thought I'd check it out. Minecraft is kind of like Lego in that you try to build houses, but unlike Lego where you start off with a bunch of bricks, in Minecraft you have to dig (mine) for the resources to build (craft) your house. Unfortunately, there is a "day" and a "night" to the game (each about 10 minutes long) and if you don't get some kind of shelter built by nightfall, the zombies come out and kill you. I downloaded this game to my Kindle Fire, but so far I haven't made it through a single "night," because I am too slow.

What puzzles me the most about his game is that there are no instructions. How do kids know what to do? I've spent hours on Google trying to figure out how to make things work (unfortunately, Minecraft "purists" consider this cheating). I discovered that the quickest way to build a shelter is simply to dig a hole in the side of a mountain. Duh. That still doesn't protect you completely from the Zombies, because you still need light and a door, but it's significantly quicker than trying to build a house with 4 walls. I can dig or cut down a tree simply by holding my finger on the Kindle screen, but then I have to "pick up" the dirt or wood or they won't show up in my inventory for later use (who knew that to pick up items, you simply run into them).

I finally figured out how to build a door and a torch for my shelter (I needed to build a crafting table from my wood and a furnace from some stone). Maybe that is why the game is so addictive. There is a certain pride when you finally figure something out, and an incentive to try something new. Some parents might not like the destructive element the zombies impart to the game, but are the zombies any different than my little sister who repeatedly toppled my Lincoln log house when I was growing up?

Thinking Outside the Box

The other day my niece told me that her daughter, Violet, had been kicked out of gymnastics class. Now Violet is only 2-1/2 years old and she's not training for the Olympics. This is simply one of those mommy-and-me type of classes that stay-at-home moms feel the need to enroll their children in. So I wondered, what in the world could Violet have done that would have required her removal from class.

It turns out that the instructor was one of those rigid Type A personalities that we STEM teachers dread. At the beginning of class, she handed out a hula hoop to each student. Rather than twirling the hoops around their waists as the toys were intended, each was required to place his or her hoop on the floor and sit quietly inside the circle while the teacher demonstrated a forward roll. Now when I was growing up, we didn't need a class to learn how to do a somersault. My mom just opened up the back door and we rolled down the hill into the neighbor's yard, but I digress.

After patiently watching the teacher demonstrate a forward roll, Violet enthusiastically jumped up, ready to attempt the gymnastic maneuver. Unfortunately the teacher led her back to her hoop and told her she would have to wait her turn. Now don't get me wrong, I can understand wanting a little bit of order, but there were only 3 students in class on this particular day. The instructor couldn't handle 3 kids doing somersaults at the same time???

After repeatedly trying to confine Violet to her hula hoop circle, the instructor finally gave up and asked her to leave the class. It never ceases to amaze me how some teachers can crush the spirit of a young child with their compulsive need to ensure order and rigid control over a simple exercise. And we STEM teachers wonder why our students have such a hard time thinking outside the box.

Winter Projects

I bought 3 new project books to take away the winter doldrums. Two books are from Wiley Press and have basically the same theme (electronic projects for kids), but they have different platforms. Becky Stewart's book is focused on the Arduino, and Carrie Anne Philbin's on the Raspberry Pi. I also bought Simon Monk's book on programming the Raspberry Pi with Python. These should definitely keep me occupied when the snow is accumulating outside.

I finished the beginning section in the Arduino book - getting the Arduino connected to my computer, uploading a sample program, and getting the onboard LED to blink. Between the book and the Arduino website, I found the setup instructions to be fairly straightforward (though you have to assume that screenshots aren't always going to match exactly given the way operating systems constantly change). There are many Arduino models on the market, but I decided to use the Uno as it seems to be the most common right now. What I like about the Wiley books is that the chapters are called "adventures." They don't just tell you to upload an example file and move on, but they step you through the code explaining each command. Plus at the end of each adventure, they ask you to build something hands-on. In the first adventure, they want you to build your own LED circuit, not just rely on the one built into the Uno. I think this makes it a lot more engaging for the students.

LEGO Cherry Picker

I've been trying to build some of the other designs from the LEGO Remix building instructions published on the NXTStep blog, but there are a few building elements that I'm missing. The one on the left is a 1M beam with 2 cross axles positioned at 90°. It's an incredibly versatile little piece giving you the ability to make connections in 3 different directions. But it is so compact, that I have not been able to come up with a way to duplicate it using the pieces in my EV3 robotics set. The element on the right is a 3M connector. The first unit of length is a traditional friction peg; the other two-thirds are a 2M axle. I've been able to get away with substituting 3M axles for this piece, but having a friction peg on one end makes the connections a little more stable.

The other day I discovered that the Cherry Picker kit comes with 4 of the 1M beams and 2 of the 3M pegs. It was very reasonably-priced from the LEGO store ($12.99), plus they threw in a free NexoKnights mini-fig. The cherry picker is somewhat small, but it has a very clever mechanical gearing system to raise and lower the boom. It only uses a 24T gear and a worm gear (the black 12T gear is not part of the gear train, but is simply used as a turning handle). What a great teaching tool for kids. 

Robot Remix - Helicopter

Last summer, the LEGO MINDSTORMS Community Partners were challenged to come up with a creative design using pieces from the EV3 LEGO Robotics kit (31313) and the new LEGO Technic Fire Plane (42040). Four designs were chosen:  a helicopter that flies in a circle, a cat that turns his head back and forth, an airplane that transforms itself into a standing winged robot, and a dancer that shakes his hips like Elvis Presley. Each design was clever and unique, but clearly fairly sophisticated in their engineering and programming. A few weeks ago, the NXTStep blog published the building instructions and program files for all 4 designs. I was intrigued by the helicopter, but I don't have the Fire Plane. I do, however, have the LEGO Technic Fire Truck (8289), so I decided to give it a try.

What I discovered is that most of the specialty pieces from the Fire Plane set are not functional, but structural. Consequently, it was quite easy to substitute something similar from elements I had on hand. My biggest concern was the helicopter blades, but the swords from the EV3 home edition worked well. The only difficult part was figuring out how to attach them to the rotor in a way that would allow them to spin freely and provide the lift needed to lift the tail and spin the helicopter.

It took me 2 tries to build the main body of the helicopter (the gearing system is very complex). The hardest part was not having access to the original CAD files so that I could observe the model from different directions. The pictures in the building instructions are quite good, but with all the black on black pieces, it's difficult to see how to connect the lower section to the upper section in the last few steps.

I think this is a great STEM activity for those fast finishers who need an extra project. Challenge them to build the helicopter (or one of the other Robot Remix models) using only the components you have on hand in your classroom. Give them the building instructions knowing they are going to have to improvise at points along the way and see what they come up with. Remember, this is a working model, not a decorative one, so "close" isn't good enough to get the copter flying. Good luck and have fun.

Wheelie Bot

The first model in the Tetrix Prime robotics kit is called WheelieBot. WheelieBot is a 3-wheel robot that uses a continuous rotation servo motor on the back wheel for motion and a standard servo motor on the front axle for steering, It's a good starter robot for a beginner, because it is quick and easy to put together. But let's face it - it's boring to drive. WheelieBot has no speed and the steering is abrupt and jerky. I can't think of a better opportunity to introduce a lesson in gears.

Let's first tackle the speed issue since everyone likes to drive fast. To increase the speed on the back wheel, I need to use a method called gearing up. In a gearing up arrangement, a large driver gear is attached to the motor and a smaller follower gear is attached to the wheel. I removed the continuous motor and replaced it with a small 40-tooth gear. My intention was to move the motor back just enough to add a large 80-tooth gear, but the wheel kept hitting the motor housing. I could have avoided this problem by putting the gears on the same side of the beam as the wheel, but then the robot would have been significantly unbalanced (being a 3-wheeled robot, it tends to tip as it is). Instead, I added a second 40-tooth gear to act as a spacer. The additional gear doesn't influence the speed, but it has the added benefit of keeping the wheel turning in the same direction as it did without gears (teachable moment:  an even number of gears changes the direction of rotation; an odd number of gears, keeps the direction of rotation the same). Since the 80-tooth gear is twice as large as the 40-tooth gear, the speed is doubled. If you watch closely, you can see that every time the driver gear makes one complete turn, the follower gear turns around twice resulting in a much more exciting robot to drive.

Unfortunately the faster speed only compounded the abruptness of the steering often causing the robot to tip over. In this situation, I wanted to slow the steering down giving me more control over the steering. This gearing method is called gearing down. In a gearing down arrangement, the 40-tooth gear becomes the driver and the larger 80-tooth gear becomes the follower. I removed the beam attachment hub and replaced it with the 80-tooth gear. You need to make sure the set screw on the gear faces up, so that the 2 nubs on the underside of the gear fit into the holes on the cross beam (the beam acting as the axle between the two wheels). This gives your robot much more stability. You'll need to use two shaft collars to attach the two beam sections together. Make sure all set screws are facing forward before tightening otherwise the front wheels will be out of balance when you turn the power on. I made all these improvements using only the elements in the basic Tetrix Prime kit. It would have been nice to have some additional bushings and another 40-mm axle, but my robot seemed to drive fine without them.