Proof of concept - body design

Now that I have the majority of the droid parts, I wanted to make sure it would all go together as I imagined it in my head.  The only thing I was lacking was a front wheel caster.  I searched the web and couldn't find anything small enough (at least, not one in my price range), so I made one out of a metal coat hanger.  The rest of the body frame is made out of balsa wood because I needed it to be as light as possible, yet have good potential for sturdiness (I used to make balsa wood structures that held hundreds of pounds of weight for Odyssey of the Mind in middle school).

Now I know what proportions to fix for the final design and what else I need to make room for.  In this build, the gearbox is on the bottom level, my arduino and motor shield are on the 2nd level, the motor shield power box is on the 3rd level, and the arduino power in taped on top.  I still need to make room for the wave shield, a speaker, and a motor (or stepper) to rotate the dome on top.

Rebuilt chassis - successful modification

As I was testing out the chassis, I realized that the way the instructions told me to build it, the wheels would not be independent from each other.  There's a third hex axel that runs through the whole assembly (see the red arrow), and the gear boxes are bolted in place to both ends.  So I had two choices: a) rebuild the chassis using the low speed option (4 times slower than the normal mode), or b) attempt to cut this axel in half.  The pieces couldn't possibly fall out, and with the hex bolts in place on both sides, they should still function like normal... they just won't affect the other side.  I opted to cut the axel in half... and it worked!  Now both wheels are independent from each other.

Hooray engineering!!!

Minor hiccup - suspend disbelief

I've completed the chassis, and have realized that I haven't been accounting for the actual shape of a proper droid until now.  The body tilt when on three wheels keeps the wheels away from the body, which means to be accurate I would need to run belts down the legs to turn the wheels instead of just connecting them to the axels.  I may have to fudge this and attempt the more complicated drive system for a future revision.

(R2D2 picture from Google search, link here:)
http://27.media.tumblr.com/tumblr_l415r2rV0W1qc7oabo1_400.jpg

More parts - chassis

I went to my local hobby shop to ask about wheels, since I've never built something like this.  I talked with him about how you should properly attach wheels to a motor, so he pointed me in the direction of these gear boxes.  I know I need two independent wheels, so this twin motor gearbox seemed to be the way to go.  The gentleman who helped me also said that he thought this would work, and would give me something sturdy to support the droid.

Making the controller work (part 2)

It took some trial and error with Ardiuno pins, but I finally got my controller to work with Bill Porter's demo sketch.  After making sure everything was working, I prototyped a mounting board to attach my Arduino Fio to the controller, as well as a port for connecting the FTDI cable prior to getting the XBees working.

Making the controller work

So I set to work hacking the controller.  As I was researching, I came across a website of someone who has already written an Arduino library for PS2 controllers!!  That takes care of weeks of researching and trial and error programming. 

Bill Porter's website is well documented with instructions on how to get up and running.  He also actively reads his comment section to help other people troubleshoot their controller.

http://www.billporter.info/playstation-2-controller-arduino-library-v1-0/

Finding the right components (part 3)

I also needed a cheap controller to hack.  I did some searching online and saw that PlayStation 2 controllers have been successfully hacked, so I bought a $10 PS2 controller.

Finding the right components (part 2)

I want my droid to be controlled wirelessly, so I needed to pick up some XBee modules for communication.  Also, in order to interface prior to getting the wireless stuff going, I needed to get a USB to FTDI cable and an XBee adapter kit from Adafruit.

Finding the right components (part 1)

The first thing I needed to figure out was what parts to get.  I knew I'd need another arduino, so the search began.  I came across this Arduino Fio, which has a built in socket for an XBee module.

Pictures to come... my camera is on the fritz...

Muahahaaaahaaaaa!!!!!!

Phase One of my evil plan has been completed!  I have convinced my professor to allow me to build a droid as an 'assignment'... I will chronicle this endeavor here so that when I have finally taken over the world, I'll be able to show everyone how I did it!!!  Nothing can stop me now!!!