Sensor for remote position

Hi! I’m Robert and i need some help, because i’m almost new on the use of Arduino and i don’t know what i have to buy for my project.
I mean i need that Arduino recognizes my position with a good precision and move a stepper motor after set up a distance that it have to maintain.
In other words i need that Arduino follow an object with a sensor inside or maybe a phone.
What i have to use?

Thank you so much.

Roberto

I don't understand your project requirements. Could you be more specific? You use vague terms like "position" and "sensor" and "follow". Are you building a robot to follow you around? Are you building a camera platform to point at a moving object?

Start by saying how you want your device to behave.

Do not forget to also provide if project will work inside or outside and at what distance between objects. These will affect choices of devices.
Lastly I have read many replies to project ideas but then find out that budgets for someones project is very small which can kill a lot of solutions.

Excuse me, practically i have this platform on two pipes on a work desk and i need that if i am on the other side of the desk this come to me, and generally if i move in a direction this platform have to move in this direction too.
Now i'm using normal infrared sensor but if they don't see me the Platform doesn't move, so i want this "thing" and put it in pockets that send a signal to the platform of where i am so it can follow me.
But i want to do it with a phone connection too if is possible or maybe easier.

I need that this system works for 2 meters as well as 60 meters, about the budget is not very high, i mean i can start with something not really good for try it on 2-4 meters and spend more when i'll need it on 60 meters.

So the pipes are working like rails to guide the device. I assume the pipes are straight and parallel.

Let's call the axis of the pipes the X axis. Are you moving only along the X axis? If not, How far from the X axis do you need to be tracked? What should happen if you go outside of tracking range (too far away or off-axis)? What if your device reaches the end of the pipes?

As you can see there are still lots of details that you have left out.

The pipes could be long 4 meters as well as 60 meters and i need that the platform that moves on the X axis can find me in this space.
when the platform arrive to the end there are already two sensor that stop the platform.
the motor is on the platform.
If i go outside the tracker range the platform should stop.