Object recognition is a difficult problem in itself. Implementations of it are even more difficult because of the different layers of complexity: data capture, training, detection. Add several layers of complexity for each of those, as well as some robotics integration problems and you see where it’s going.
The following tutorials do not go over the object recognition steps in order of execution but complexity. You probably need the last tutorials fo your real world applications but the first ones will actually make sure that your setup is fine.