Category Archives: engineering

engineering, student project

Square One Autonomous Innovative Vehicle Design Competition

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Square One Education Network hosts a number of events every year. These include high quality Professional Development as well as student competitions. For the last three years our students have been competing in their Autonomous Innovative Vehicle Design Competition. The goal is to turn a Power Wheels Jeep into an autonomous vehicle. For this competition Square One provides the Jeep and also gives teams money to buy parts and supplies.

I’ll be documenting some of what my students have done this year here in this post. I’ll be updating this post with pictures, more details on parts, and all of the code (that will likely be after the competition)

Parts and Sources:

Things to Know/What we used these parts for:

You need some sort of a motor controller to allow your Arduino to regulate the current from the battery to the drive motors. We’ve used the Monster Moto Shield from SparkFun every year and it works like a champ. This will let you run the motors forward/backwards and give you a measure of speed control. You’ll need to solder on header pins and screw terminals, so be sure to order those at the same time. One weird thing we just discovered. We ran into a motor control problem last night that could only be solved by disconnecting an ultrasonic sensor from pin A0.  So, we’re avoiding pin A0 altogether for now.

The wheel encoders we found didn’t fit at all. The hole was too small, so students used a soldering iron to melt the rubber bushing to enlarge the hole. They then used a little superglue to affix the encoders to the really short shaft sticking out of the motors. Maybe next year we’ll be able to find some encoders that actually fit, but these seem to work for now.


The steering servo works well. If you buy one from ServoCity they offer to assemble the servo for an additional $30. I highly recommend you take them up on this. It’s not just putting the gear box together. It includes taking apart the servo itself and doing some modifications involving soldering and cutting a bit off a gear. I’ve bought two of these over the three years. This year we paid the $30. Totally worth it!


Our code is still being written. It will all end up in this Google Drive Folder when we’re done.

electronics, engineering, make and take, physics

Paper Circuits

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I’ve been teaching a semester long electronics class every semester since I started teaching in 2000. It started as a basic circuits course, but several years ago I started teaching it with the Arduino micro-controller platform. It has undergone several transformations over the years and I’m changing it yet again this semester.

We’re starting with some basic circuit fundamentals. In the past I assumed they would learn these fundamentals as we worked with Arduino. It turns out I was wrong. One of the circuit building things we did this week involved making paper circuits. This worked out really well and gave students a chance to discover differences between series and parallel circuits. They also got to do some trouble shooting to figure out closed, open, and short circuits.

All in all it was a fun project to help set the tone for the semester while also giving us an activity we can refer back to as we move forward.

Parallel Paper Circuit

Recommended resources:

arduino, electronics, engineering

Arduino RC Car Part 2

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Tony DiLaura asked me about tutorials for high school students to build Arduino controlled RC cars. I didn’t really know of any that I liked so I started outlining what one might look like. This is part two, you might want to check out part one first. This post will be about control mechanisms.

In my last post I said my students had never made remote controlled cars. It turns out this was not at all correct. I’m getting too old and the memory begins to fade. It’s a good thing the internet never forgets. In this post I’ll share some that my students have made in the past. In the next post I’ll dive into ones I’ve seen on the net but haven’t tried yet.

Wiichuck

WiiChuck carOK, this one isn’t radio controlled, but wired instead. It uses the Wii Nunchuck to control your circuit. I suppose if you have a wireless nunchuck you could also make this wireless. If you have to buy a nunchuck this might not be the cheapest option, but I bet one of your students has one at home in a closet somewhere. You can chop the end of the Wiimote plug or you can buy a cheap adapter

  • SparkFun $1.56 – Cheapest and I’ve used this one in the past
  • Adafruit $3.00 – Might be a better option. Looks like it’s designed to snap in and stay in a bit better.
  • WiiChuck Page – All about using a WiiChuck with Arduino including a library download
  • Lego – Lego Electronic GizmO – Lego robot controlled by Arduino and Wiichuck created by my students several years ago. Includes some sample code. Uses the joystick because the accelerometer was a bit too twitchy for them. That could have been solved with programming.

TV Remote

zwally-IR RobotWe’ve also had luck controlling Arduino robots with old TV or VCR remotes. Be aware that some work far better for this than others. The only way to know is to experiment. This is really in the same price range as the Wiichuck solution and makes your car wireless as long as you have line of sight. In theory, you could also create your own remote using a second Arduino and IR LED, but I’ve never done this.

Keyfob

rf receiverI’ve also had students use a keyfob transmitter and receiver. This uses RF and is probably the simplest from a programming standpoint. If your students can program an Arduino to respond to a button press then they know everything they need to to make this work. I don’t have any links to the modules my students used. I can’t remember where I bought them from. Which is probably just as well, they worked, but were not great. However, I did find virtually the same thing on Adafruit’s website. I trust Adafruit to have good stuff.

 

3dprinter, arduino, electronics, engineering

Tutorial for an Arduino RC Car?

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A buddy of mine recently sent me a tweet:

RC Arduino Tweet

This is an interesting question the short answer I have is, “No.” The longer answer is a bit more nuanced, so I asked for a little clarification. This is what I got back:

RC Arduino 2

Now I had a lot more to go on. With this in mind I have something to sink my teeth into. Now we have something, so now my response is, “No, I haven’t seen anything that would fit.”

OK, now that that’s out of the way lets cover how I would tackle this problem. Tony is an awesome math teacher in Zeeland, Michigan. He co-teaches a project based math/physics class. I’m going to work from the assumption that he’s working with students starting with little previous knowledge of electronics and Arduino programming, and that he’d like to leave as much room as possible for students to explore. Everything I cover will be with that in mind.

With a project like this you need break it up into pieces. I’m going to think of this as a robot even though it won’t be autonomous because we still will have a computer controlling an independently moving device. As with any robot type project you have three fundamental challenges, the programming, the electronics, and the mechanics. However, with this project we’ll need to consider a forth part I don’t usually think about with a robot, and that is the control mechanism.

Mechanics

You could go crazy with this and start with a platform like Tuggy from the very cool OpenRC Project. While totally awesome I think this takes all of the thinking away from the students and simply turns them into mechanics. Which is fine if that’s your goal. Instead I’d start with ThinkFun’s MakerStudio collection of building sets.

macaroni box car

You can buy sets or download and print from the Thingiverse. I’d start by having students play with the gears and such and make simple cars with parts available, then begin thinking about what their RC car needs. They’ll need to make a variety of decisions. How will their cars be steered? Will they use skid steering (like a tank) or rack and pinion (like a car)? What sort of  platform will they need? I’m not sure a Mac & Cheese box is the best choice. How many motors will they need? Will they use gearbox motors or simple DC motors and then use the gears in the set? Some of these decisions might be made by the teacher and some or all might be left out the students. I’d probably go with simple DC motors and use the gears from the set.

Once these decisions have been made students can then think about the parts in the MakerStudio kits they don’t have but need. Things like motor mounts, rack and pinion mechanisms, bits to mount the gears to the platform of choice, and such. These could should all be designed and 3D printed by the students.

Electronics

Tony asked for Arduino, so we’ll stick with that. It also doesn’t hurt that I know a lot about using Arduinos with high school students. Unfortunately, you can’t run any sort of reasonable motor directly from an Arduino. You need some sort of transistor or h-bridge. Digital outputs on your Arduino only put out 40 mA, this is woefully inadequate to power a motor.


Students can wire an h-bridge themselves, but I highly recommend using a motor shield. I’ve had many students use an h-bridge and breadboard their circuit which mostly works. There are a lot of connections that need to be made and by the time students got to soldering stuff together numerous problems would typically crop up. In order to get around a lot of headaches I now have students use motor shields and skip all the complex wiring. You can buy shields from China really cheaply, but I like to use SparkFun Electronics. SparkFun is based out of Colorado and they offer an educator discount of 20% and allow you to easily set up payment accounts allowing you to pay via purchase order. The other thing I really like about SparkFun is that they include code example and/or tutorials for almost everything they sell. So I can hand a shield to a student and then point them to the product page and step back.

Most motor shields will allow you to control two motors, perfect for skid steering. If your students chose to go with rack and pinion then you can get away with one drive motor, but you’ll need a servo-motor for steering. There are lots of tutorials for controlling servos with Arduino and ideally where ever you get your motor shield will tell you how to wire your motors to it and give you a simple program to control your motor(s).

Other Stuff

At this point we just have programming and control mechanism left. I have some ideas about control mechanisms, but I haven’t done any of these in the past. When I say “I” that really means my students. So, I’m going to do a little more research and then another post. More than likely I’ll be looking at some sort of the cool BlueTooth module and an app running on a cellphone or tablet. There are other ways, but controlling a robot with your phone is just too cool.

3dprinter, engineering

Getting Started with 3D Printing – Lets make something

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OK, it’s been a couple of weeks since my last post. I’ve decided to do an instructional post to break things up a little. One of the projects I had my physics students work on last year was an engineering/design problem. I simply asked them to create an accessory for their cell phones. This idea was not original to me, but I honestly can’t remember where I got it from.


In order to actually make their own accessories my students needed some sort of program to create a 3D model. Our school doesn’t currently have drafting or CAD classes, so I was left with only a few options. We have no CAD software and even if we did, my students wouldn’t know how to use it.


I settled on cloud based solution, Tinkercad, for my students. Tinkercad is very simple, which also means it lacks many functions you’d expect in a traditional CAD program. It is also run in the cloud so it can be slow at times, but on the plus side if your computers have Chrome there is also nothing to install. This can be a huge plus in an educational environment. I use Tinkercad at least in part for almost all my 3D printing projects.


The basic idea behind Tinkercad involves building models by joining together simple shapes. Shapes can either be solids or holes. It seems like this would be a difficult way to create anything, but as it turns out you can create some very useful models with this very simple idea.

I originally found this phone stand on Thingiverse. I like it because it holds the phone up a little higher than most of the ones I’ve seen. I’ll show you how easy Tinkercad is to work with by recreating it. We’ll talk about the phone case in a future post.

If you have students create accounts for Tinkercad please steer them away from using their Facebook or Twitter accounts. In the past I’ve had a few students create accounts at home using their Facebook credentials. We block Facebook, so they were unable to access their accounts at school.



Go Back to earlier parts in the series: Part 1, Part 2, or go on to Part 4