Automated guided Vehicle

I am trying to make an automated guided vehicle that will first move in a space(as of now in a restricted area with few obstacles) and correspondingly make a map of the area. I am making use ultrasonic sensors,Arduino Mega, Stepper Motors.
I came across this term called SLAM(simultanious localization and mapping ). I have tried to understand the same. The concept is fine but implementation seems complex. With the accessories that i have, is how do i go about making a bot that can map the surrounding?

The concept is fine but implementation seems complex.

Which explains why you can't find any code for the Arduino that does it.

Not only is it complex, but it requires a lot of memory.

I am planning to make use of a bluetooth module to send the sensor value onto my pc. Then using matlab I will plot the map.
But then what i am wondering is how will i ensure that the bot covers the entire area ?

Perhaps, i think this could help you:

My Personal Robotic Companion
My Personal Robotic Companion Library

or

Arduino & Mathlab SLAM