Building Robots at School

June 22, 2011

Jason’s “No-Fun” Guide to Uncrating the Cortex Classroom Lab Kit

Filed under: Uncategorized — dtengineering @ 11:58 pm

The VEX Cortex Classroom Lab kit is the kit I recommend to most teachers wanting to get started with VEX. Add in a copy of EasyC V4 (or a ten seat lab pack if you’re planning to expand beyond one or two robots) and you’re ready to start building some pretty cool robots. You’ll need a few extra parts, some omniwheels, and a few extra motors (maybe a couple of high strength motors?) to build a full-on competition robot, but you can choose those specific parts as you develop your design for the competition. The classroom lab kit, however, forms a great place to start.

There are a few things to watch for when opening a classroom lab kit, and a few things you can do now — easily — that will pay off in the long run. There are also a few common mis-steps, and… as of this writing… some glitches in the manual. So here’s my tips on how to uncrate your Cortex lab kit as efficiently as possible.

UPDATE: The glitches that I mentioned have been fixed. If you are building the “Protobot” or “Tumbler” please read the latest version of the Protobot/Tumbler build instructions. They have been updated with Cortex specific assembly instructions, including using the new two-wire motors and speed controllers.

Step 1: Where are you going to put all this stuff?

There are a LOT of parts packed into that lab pack. If you have a nice, tidy, storage system in advance of the uncrating, then you will put everything into a nice tidy arrangment. At the high end of the line is the Stanley Fat Max, but pretty much any 18″ long toolbox with multiple compartments will be a good start. When I taught at David Thompson each team got one of these hefty beasts. They were heavy, but the fold out compartments were fabulous. No matter how good the toolbox is, however, it won’t be enough to handle all the tiny little parts. My favorite parts boxes cost a little bit more than the cheap ones that have the adjustable dividers, but I find it is worth it as the little dividers inevitably fail, and you end up having a hard time keeping your parts organized. Check out your local hardware store for a solution that you’ll be comfortable with. Having one tool box and one parts organizer ready to go when you open your robot kit will save you time in the long run.

Step 2: How are you going to label all this stuff?

Every VEX part looks like every other VEX part. Your joystick looks exactly the same as the other school’s joystick… your VEXNet keys are identical… and students get them mixed up with each other’s stuff very easily. My adult post-secondary students demonstrated this to me when they took their new robots to an event and came home with extra vex net keys but missing joysticks. It was very sad. Now all our electronic parts… joysticks, batteries, VEXnet keys, chargers… all that expensive stuff that is easy to misplace is labelled. If you’ve got an engraver, that is great… but most VEX people are pretty honest. They won’t pull off labels or erase them… they really do want to get your parts back to you if you leave them at an event. If you want to get really fancy, label and number each of the major parts so you can keep track of them within your classroom. “BCIT 1” is marked on the joystick that goes with the Cortex labelled “BCIT 1”. At least label the electronic parts as they come out of the box, and you’ll be happier. In fact proper labelling is so important that we are considering adding a rule to tech inspection at BC events next year REQUIRING all teams to have their joystick, batteries and VEXnet keys labelled for easy identification. Label makers, engravers, paint pens, sharpies… even just pen on a piece of tape will save you a lot of hassle at some future point. Now enjoy this annoying animated .gif showing how I uncrate a Cortex kit….

Step 3: Open the box!

I know… you immediately skipped over points one and two and have already started pulling things out of the box, haven’t you? That’s okay… I did it too… and after you’ve opened many VEX kits you’ll come to see why I’ve put steps one and two ahead of opening the box. The first order of business after labelling the components should be to put your new batteries on to charge. You are going to be wanting them later.

Take the time to identify your parts, and pay particular attention to the motors and speed controllers. They are new and not described in the manual on how to build the protobot or tumbler projects. The new motors are an improvement, but it will take a while for the manuals to catch up. (The manuals have caught up… see the “Update” above, for the link.) For now, just plug the “two-wire” motors into a speed controller, and then plug them in to the Cortex. They will behave just like the old “three wire” motors did. There are also two special motor ports on the Cortex that you can plug a two-wire motor into directly. This is because there are already two speed controllers built in to the Cortex… see how port 1 and port 10 are different? There is more information on this in chapter 7 of the manual. You may as well read it now… the batteries are charging anyways.

Step 4: Build a Robot

Either the protobot or tumbler are a great starting point. Just remember that your batteries, motors and microcontroller are a little bit different. If you want a Cortex specific model to build, you can check out Carnegie Mellon University’s pages.

Step 5: Pair the Joystick and Cortex

Did you notice the sheet of paper labelled “important”? Many of my students don’t. Then they wonder why the robot doesn’t work. Once your batteries are charged follow the instructions and you will unite your Joystick and Cortex controller so that they will only communicate with each other. (Should you need to match the joystick up with a different controller later, you just repeat the procedure with the new controller.)

Step 5: Try It Out!

Remove the USB cable and insert a VEXNet Key in the Cortex and one in the Joystick. Turn the robot and joystick on. Wait patiently while the LEDs blink. If they all go green, you’re good to go. If your robot doesn’t go, perhaps you need to try plugging the speed controllers in to a different port. Try a few different combinations and you’ll figure it out quickly enough. If you aren’t getting green lights on your Cortex and Joystick, check out the manual, particularly page 8. There is also an outside chance that your school (or some malevolent force) is shutting down unrecognized wi-fi devices. If your school uses a Wireless Intrusion Prevention System, you need to go here, then talk to your IT support folks.

Step 6: Upgrade the Firmware on the Cortex and Joystick

You need to download the latest software updates for your Cortex and Joystick. There should be a .pdf file included in the .zip file that you download that should walk you through this process. Note that for Cortex-specific instructions you jump ahead to page 6 and begin at option “C”. You may need to repeat step five following the upgrade, and if you jumped ahead to step 7 and downloaded your own code, you’ll have to download it again… everything gets “zapped” when you do a firmware upgrade.

Step 7: Get Programming

You can download a trial copy of EasyC here… but it is only good for seven days. If you have purchased an EasyC CD, you can use the code on the CD to validate your downloaded copy, thus ensuring that you have the latest, most up-to-date version of EasyC available. There is a section on programming in your manual, and plenty of assistance available through the VEX Forums.

Step 8: Regret Having Not Followed Step 1 and Step 2

Yeah, right. Like you actually followed that advice to store everything carefully and label all the “easily lost” bits. Now you’re wondering where all the collars have gone, why you can’t find a “motor screw” to save your life, and how you ended up with two Cortex batteries, but are missing a VexNet key. I suppose there are worse problems to have….

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2 Comments »

  1. Thanks for the post. I’m a teacher hoping to start the first Vex club in Saskatchewan this fall and I appreciate your tips.

    Comment by Jeff Walso — May 13, 2012 @ 1:11 pm | Reply

  2. Wow, this piece of writing is good, my sister is analyzing these things, therefore I am going to let know
    her.

    Comment by www.ziplineguru.wordpress.com — December 7, 2013 @ 10:18 pm | Reply


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