What are the options for determining the position of an object in a confined space?

Question

Arduino

I decided to get into robotics.
Total newbie so sorry for the stupid question.
How to determine where in space an object is located?
Let's take ideal conditions as an example. (Box 2x2x2) how to determine the coordinates of an object in a box (Robot Object).

Answer 1

1. The object itself remembers the distance traveled relative to the base point. Primitive but cheap.
2. Universal way - GPS. The positioning accuracy depends on the price very disproportionately.
3. System of sensors (ultrasonic, infrared, laser). The most accurate way, but only works in a confined space (your case). Positioning accuracy is roughly proportional to price.
....................
100500. Combined method.

Answer 2

camera to look at the object. + open sq.
sound signal + several microphones to determine the phase difference of the signal arrival.
you can probably do the same with the LED and receivers.

Answer 3

I myself build a similar robot, use a sound range sensor, evaluate the space, then I will look for a way to move myself.
I mean his movement around the room, kitchen and corridor, independent.
And return to the base for recharging.