Both the fields are related to each other for Robotics field, but neither of them, are not the only fields through which you can enter Robotics. There are numerous fields through which you could, enter the Robotics domain. As there are examples of people coming in from totally unrelated fields like, Psychology, Law, etc., As such there is no Artificial Intelligence course for which you can acquire a bachelor’s degree from colleges, as it's still evolving and rapidly enhancing. But few colleges have started giving and in coming days, we will see the big change.
It's good to go with Computer Science, as it is most preferred career path to make a change, to any IT-related field. And Robotics is not a narrow field, it has several domains, converging together, so, for the safe side, it better to go with Computer Science, rather than AI, keeping in mind AI is the booming technology right now. I suppose you are in your high schools, so you might know the present-day happenings in the Robotics field much, so keep reading, learning new stuff, and if possible, enroll in a good Artificial Intelligence course if you are into AI, in your college days when you know more about the field.
You could get started, by watching the following video on Artificial Intelligence tutorial for beginners.