Hello, my dear readers!
After an extraneously long Coffeemecha hiatus, I have once again returned in an effort to complete this wonderful mobile coffeemaker.
Some Minor Changes
Picking up where we left off in my last post, I've finished all the wiring and (most of) the hardware work on the Coffeemecha. Like any robot, some significant design changes occurred towards the end of the build process, including...
The Raspberry Pi and SSC-32 Have Been Replaced
Yes indeed, I've replaced two boards with a single, wonderful, board called the Arbotix robocontroller. The Arbotix is kind of like an Arduino...designed specifically for robotics!
I made the decision to switch primarily due to the fact that the Raspberry Pi running a dedicated server was, put bluntly, overkill for something like the Coffeemecha (in its current state, at least). As it is, the Coffeemecha is already being run by an external server that handles all the logic - why make it any more complex than it needs to be?
The Wi-Fi Communication System Has Been Replaced
Naturally, since I switched over to an Arduino-style platform, Wi-Fi communication is far too...cumbersome...for the Coffeemecha. Ergo, I've replaced the router with brand-new XBee modules! These guys have always been my favorite method for communication, due in part to how they're basically just wireless serial ports, but also thanks to the fact that they have just insane ranges both indoors and out (and other wireless systems hardly interfere with them at all).
Indeed, XBee modules were the natural choice for the Coffeemecha.
The Rubber Tread Inserts Have Been Removed
"Wait, what?" is what you're probably thinking right now. What kind of crazy dude would remove the only element providing traction to a pair of treads?
Well, the answer is, clearly, me.
It turns out that if you have too much traction (or in this case, any traction at all), the treads will sort of "skip" on hard surfaces, making the Coffeemecha go from a smooth and gracefully moving elegant barista to a...robot with some kinda sugar rush? I'm not sure, but it wasn't good.
With the rubber inserts removed from both sets of the Coffeemecha's treads, it now moves smoothly and gracefully along my
thoroughly scratched and ruined hardwood floors. Of course, it does slide a little bit every now and then...but hey!
What Did You Use To Make It?
The Coffeemecha's bill of materials is relatively short, considering that it's a fully converted mobile coffeemaker (note: it doesn't actually brew coffee anymore). The parts used include:
An intact Starbucks Barista frame. Red is preferable, since it goes faster (clearly).
Two standard TETRIX brackets for mounting the treads on.
Four TETRIX tread idlers.
Two TETRIX tread sprockets.
A good amount of TETRIX tread links.
Two TETRIX motors along with their corresponding mounts and cables.
Two IFI Victor Motor Controllers for controlling the TETRIX motors.
One Arbotix Robocontroller board.
Two XBee modules (one on the Coffeemecha, one on the control system).
A good amount of 12 and 18 gauge wire for, well, wiring.
A good amount of Anderson Powerpoles for handling power distribution.
Two PWM signal cables for connecting the Arbotix to the Victors.
A simple power distribution board for the Anderson Powerpoles to, well, distribute power.
One NiMh TETRIX battery for powering the Coffeemecha.
And a safety beacon. Because I can.
In addition to the parts listed above, I also used various zip ties, cable tie mounts and TETRIX fasteners to help tidy things up and get everything installed.
Frequently Asked Coffeemecha Questions
Below are some of the questions I receive about the Coffeemecha on a daily basis. As more questions pop up, I'll add them here...maybe. ;3
Q: How fast does it move?
Assuming a standard TETRIX motor with an average RPM (revolutions per minute) of about 152 and a drive sprocket that's about 2.5 inches in diameter, we can calculate that the average speed in inches per minute is about 380 (152 * 2.5). This comes out to roughly 31 feet in a minute, or 0.5 feet per second. Of course, these numbers assume absolutely perfect conditions, meaning that, in reality, we can expect the Coffeemecha to go a little slower or faster depending on all kinds of things.
TL;DR: The Coffeemecha travels about half a foot per second, give or take a few inches.
Q: Does it actually brew coffee?
No. Unfortunately, while I'm a decent roboticist, I'm terrible when it comes to hoses and liquid and...things. However, it can serve already brewed coffee - surely, that's cute enough?
Q: Can I have a copy of the control system?
Not yet! It's still in a pre-alpha stage (and lacks a good name, which is always important). Please wait a little while longer for me to release the public API and binaries for it!
Q: Can you make a Coffeemecha for me?
Yes! Please contact me at firstname.lastname@example.org if you're truly interested in having a Coffeemecha of your own. Please know that you'll need to be able to provide me with an original Starbucks Barista frame that's in good condition, as well as about $600 for the parts and materials required to convert the original coffeemaker into a robot.