I want to build a system that attached to an robot would tell the position of the robot. The robot is assumed to be in a predefined space. The base idea that I want to use is the triangulation. Ex: the space in what the robot moves is an rectangle. In one corner is the origin of the system and in the other three, fotodiodes that receive the signal from the moving system. Please send me some ideas or links of something similar. I would appreciate more details if possible. Thanks!