This is a kit that I got from the Air and Space Museum in Washington D.C. for only 15 dollars. I dont know if it is really a robot because its just a motor and a battery with some plastic. The robot is supposed to just walk around but, I upgraded the motor to a faster one, which allows me to carry full cans of soda instead of just an empty one. It has a thing called "cams" instead of wheels which create a sense of walking. I may swap out them with wheels from a old rc car. I dont know what is in the future for the soda bot, but I may add a arduino nano and some sensors. For know its just a dumb robot that has no sense of its environment. If you want to buy one here is a link to one: http://www.amazon.com/Toysmith-4M-Tin-Can-Robot/dp/B0014WO96Y
Maybe it can be usefull another way. Hook up a Arduino, and program it to follow you. Anytime you need a soda, you just have to turn around! Though that would have to be changed around to keep it cold, keep it from straying away from you, and making it bigger.
I have a similar kit that my son and I put together, only instead of a geared motor with cams for wheels, it is simply a vibrating bot on legs. I wish we had your kit instead!
Something you could do is add simple sensors without a full microcontroller like the Arduino. Try a bump sensor in front that triggers a simple delay circuit and a relay so the robot backs up if it bumps into something. Or a downward pointing sensor so it stops if it sees and edge like a table, so that it won’t fall.
