Hi Andrew, This is certainly doable and there are many examples out there. I'll look thru my notes..
I am working on a 2-motor car / robot that will receive serial signals and run them as "LOGO" code. See http://en.wikipedia.org/wiki/Logo_(programming_language)
Obviously it would be best to have a radio link for this, but you can start out with storing a series of commands in the robot and then letting it go..
So the most common commands would be:
FW 100 (Forward: The numbers are distance, you have to decide what that scale is!)
RT 90 (Right Turn (degrees]
BK 200 (Back)
LT 180 (turn around)
etc... See the Logo information.
That might be enough to start.
Logo also has simple repetitive commands, so:
REPEAT 4 [FD 200 RT 90] travels in a square
Logo has the concept that the vehicle has a pen that can draw on the ground / floor / paper. I've seen some draw with chalk on the sidewalk
So those commands are PENDOWN and PENUP usually abbreviated as PD and PU.
All/most Logo commands have 2-letter abbreviations that would be good...
I plan to have two more commands:
GA (Go autonomous: according to onboard software and sensors etc. you develop)
SA (Stop autonomous: return to remote Logo commands) Possibly triggered by a hard-contact crash!
Another 'new' command usually is SP 100 (Set speed)
Let us know how you're making out with all this...
I have several different sensors etc. that I'm testing that are available here: http://arduino-direct.com/sunshop/index.php?l=product_list&c=17
DISCLAIMER: I mentioned stuff from my own Shop...