What are the ways / technologies that allow the robot to navigate the terrain?

Question

Do it yourself

Good afternoon! What are the ways / technologies that allow the robot to navigate the terrain? As one of the solutions is Googled IR sensors, the robot will be able to determine if there is an obstacle in front of it or not. The problem is that I have not found an IR phototransistor in any store (IR LEDs are present), i.e. lack of details.
I would like to find ways that do not require very specific details.

Answer 1

Very good course with Udacity, though in English. The first part of it is completely devoted to the methods of localization (determining the position in space) of the robot.

Answer 2

There are ready-made IR rangefinders from Sharp

Answer 3

IR, US, etc.
and then - Kinect, laser rangefinder, etc.
see SLAM
making a simple IR sensor yourself is not a problem.
Good luck!